implemented lazy loading for object_ptr and belongs_to

backends/postgres/src/postgres_connection.cpp

@@ -109,7 +109,9 @@ utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> postgres_co
     prototype.at(i).change_type(type);
   }
 
-  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res), prototype));
+  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res),
+                                                                    std::move(prototype),
+                                                                    context.resolver_factory));
 }
 
 std::string postgres_connection::generate_statement_name(const sql::query_context &query) {

backends/postgres/src/postgres_statement.cpp

@@ -60,7 +60,7 @@ utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> postgres_st
     return utils::failure(make_error(sql::error_code::FETCH_FAILED, res, db_, "Failed to fetch statement", query_.sql));
   }
 
-  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res), query_.prototype));
+  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res), query_.prototype, query_.resolver_factory));
 }
 
 std::unique_ptr<utils::attribute_writer> postgres_statement::create_binder() const {

include/matador/object/object_proxy.hpp

@@ -3,77 +3,46 @@
 
 #include "matador/object/primary_key_resolver.hpp"
 
+#include "matador/object/object_resolver.hpp"
+
 #include <memory>
+#include <utility>
+#include <stdexcept>
+#include <mutex>
 
 namespace matador::object {
-
-class basic_object_proxy {
-public:
-    virtual ~basic_object_proxy() = default;
-
-    [[nodiscard]] virtual void *get() const = 0;
-};
-
-template < typename Type >
-class object_proxy;
-
-template < typename Type >
-class object_resolver {
-public:
-    virtual ~object_resolver() = default;
-
-    virtual Type* resolve(const object_proxy<Type> &proxy) const = 0;
-};
-
-template < typename Type >
-class static_object_resolver final : public object_resolver<Type> {
-public:
-    static_object_resolver() = default;
-    explicit static_object_resolver(Type* obj)
-    : obj_(obj) {}
-    explicit static_object_resolver(std::unique_ptr<Type> obj)
-    : obj_(std::move(obj)) {}
-
-    Type* resolve(const object_proxy<Type> &/*proxy*/) const override {
-        return obj_.get();
-    }
-
-private:
-    std::unique_ptr<Type> obj_{};
-};
-
-
 template<class Type>
-class object_proxy final : public basic_object_proxy {
+class object_proxy final {
 public:
   object_proxy() = default;
-  explicit object_proxy(Type* obj)
-  : resolver_(std::make_unique<static_object_resolver<Type>>(obj))
-  , pk_(primary_key_resolver::resolve_object(*obj).pk) {}
 
-  [[nodiscard]] void *get() const override { return static_cast<void*>(pointer()); }
+  // Lazy
+  object_proxy(std::weak_ptr<object_resolver<Type>> resolver, utils::identifier id)
+  : resolver_(resolver)
+  , pk_(std::move(id)) {
+  }
 
-  Type* operator->() const { return pointer(); }
+  // Eager
+  object_proxy(std::weak_ptr<object_resolver<Type>> resolver, std::shared_ptr<Type> obj)
+  : obj_(obj)
+  , resolver_(resolver)
+  , pk_(primary_key_resolver::resolve_object(*obj).pk) {
+  }
+
+  // Transient
+  explicit object_proxy(std::shared_ptr<Type> obj)
+  : obj_(obj)
+  , pk_(primary_key_resolver::resolve_object(*obj).pk) {
+  }
+
+  [[nodiscard]] void *raw_pointer() const { return static_cast<void *>(pointer()); }
+
+  Type *operator->() { return pointer(); }
   Type &operator*() { return *pointer(); }
   const Type &operator*() const { return *pointer(); }
 
   Type *pointer() const { return resolve(); }
 
-  Type& ref() { return *pointer(); }
-  const Type& ref() const { return *pointer(); }
-
-  void reset(Type* obj) {
-    pk_ = primary_key_resolver::resolve_object(*obj).pk;
-    resolver_ = std::make_unique<static_object_resolver<Type>>(obj);
-  }
-  void reset(std::unique_ptr<Type> obj) {
-    pk_ = primary_key_resolver::resolve_object(*obj).pk;
-    resolver_ = std::make_unique<static_object_resolver<Type>>(std::move(obj));
-  }
-  void reset(std::unique_ptr<object_resolver<Type>> &&resolver) {
-    resolver_ = std::move(resolver);
-  }
-
   [[nodiscard]] bool empty() const { return resolver_ == nullptr; }
   [[nodiscard]] bool valid() const { return !empty(); }
   [[nodiscard]] bool has_primary_key() const { return !pk_.is_null(); }
@@ -82,13 +51,28 @@ public:
 
 private:
   Type* resolve() const {
-    return resolver_->resolve(*this);
+    if (obj_) {
+      return obj_.get();
+    }
+
+    std::lock_guard lock(mutex_);
+    auto resolver = resolver_.lock();
+    if (!resolver) {
+      return nullptr;
+      // Todo: Add states (Detached, Attached, Transient) - if attached an no resolver is available throw runtime exception
+      // throw std::runtime_error("Detached proxy (session expired)");
+    }
+
+    const_cast<std::shared_ptr<Type>&>(obj_) = resolver->resolve(pk_);
+
+    return obj_.get();
   }
 
 private:
-    std::unique_ptr<object_resolver<Type>> resolver_{std::make_unique<static_object_resolver<Type>>()};
+  std::shared_ptr<Type> obj_{};
+  std::weak_ptr<object_resolver<Type>> resolver_{};
   utils::identifier pk_{};
+  mutable std::mutex mutex_{};
 };
-
 }
 #endif //OBJECT_PROXY_HPP

include/matador/object/object_ptr.hpp

@@ -12,44 +12,53 @@ template <typename Type>
 class object_ptr {
 public:
   object_ptr()
-  : ptr_(std::make_shared<object_proxy<Type>>()) {}
+  : proxy_(std::make_shared<object_proxy<Type>>()) {}
-  explicit object_ptr(Type *obj)
+  explicit object_ptr(std::shared_ptr<Type> obj)
-  : ptr_(std::make_shared<object_proxy<Type>>(obj)) {}
+  : proxy_(std::make_shared<object_proxy<Type>>(obj)) {}
-  object_ptr(const object_ptr &other) : ptr_(other.ptr_) {}
+  explicit object_ptr(std::shared_ptr<object_proxy<Type>> obj)
-  object_ptr(object_ptr &&other) noexcept : ptr_(std::move(other.ptr_)) {}
+  : proxy_(std::move(obj)) {}
+  object_ptr(const object_ptr &other) = default;
+  object_ptr(object_ptr &&other) noexcept = default;
   object_ptr &operator=(const object_ptr &other) = default;
   object_ptr &operator=(object_ptr &&other) = default;
 
-  using value_type = Type;
+  bool operator==(const object_ptr &other) const {
-  Type* operator->() const { return ptr_->pointer(); }
+    return get() == other.get();
-  Type& operator*() { return ptr_->ref(); }
+  }
-  const Type& operator*() const { return ptr_->ref(); }
+  bool operator!=(const object_ptr &other) const { return !operator==(other); }
 
-  [[nodiscard]] bool empty() const { return ptr_->pointer() == nullptr; }
+  using value_type = Type;
-  void reset(Type *obj) {
+
-    ptr_->reset(obj);
+  Type *operator->() const { return get(); }
+  Type &operator*() { return *get(); }
+  const Type &operator*() const { return *get(); }
+
+  [[nodiscard]] bool empty() const { return get() == nullptr; }
+
+  Type *get() const {
+    return proxy_ ? proxy_->pointer() : nullptr;
   }
 
-  Type* get() const { return static_cast<Type*>(ptr_->pointer()); }
+  void reset() { proxy_.reset(); }
 
   operator bool() { return valid(); }
-  bool valid() { return ptr_ != nullptr; }
+  bool valid() { return proxy_ != nullptr; }
+
+  [[nodiscard]] bool has_primary_key() const { return proxy_->has_primary_key(); }
+  [[nodiscard]] const utils::identifier &primary_key() const { return proxy_->primary_key(); }
+  void primary_key(const utils::identifier &pk) { proxy_->primary_key(pk); }
 
-  [[nodiscard]] bool has_primary_key() const { return ptr_->has_primary_key(); }
-  [[nodiscard]] const utils::identifier& primary_key() const { return ptr_->primary_key(); }
-  void primary_key(const utils::identifier &pk) { ptr_->primary_key(pk); }
 private:
-    std::shared_ptr<object_proxy<Type>> ptr_{};
+  std::shared_ptr<object_proxy<Type> > proxy_{};
 };
 
 template<typename>
-struct is_object_ptr : std::false_type
+struct is_object_ptr : std::false_type {
-{};
+};
 
 template<typename Type>
-struct is_object_ptr<object_ptr<Type>> : std::true_type
+struct is_object_ptr<object_ptr<Type> > : std::true_type {
-{};
+};
-
 }
 
 #endif //OBJECT_PTR_HPP

include/matador/object/object_resolver.hpp

@@ -0,0 +1,35 @@
+#ifndef MATADOR_OBJECT_LOADER_HPP
+#define MATADOR_OBJECT_LOADER_HPP
+
+#include <memory>
+#include <typeindex>
+
+namespace matador::utils {
+class identifier;
+}
+
+namespace matador::object {
+
+class abstract_object_resolver {
+public:
+  virtual ~abstract_object_resolver() = default;
+
+  [[nodiscard]] const std::type_index& type() const { return type_; }
+
+protected:
+  explicit abstract_object_resolver(const std::type_index& ti) : type_(ti) {}
+
+public:
+  const std::type_index type_;
+};
+
+
+template<typename Type>
+class object_resolver : public abstract_object_resolver {
+public:
+  object_resolver() : abstract_object_resolver(typeid(Type)) {}
+
+  virtual std::shared_ptr<Type> resolve(const utils::identifier& id) = 0;
+};
+}
+#endif //MATADOR_OBJECT_LOADER_HPP

include/matador/object/object_resolver_factory.hpp

@@ -0,0 +1,27 @@
+#ifndef MATADOR_OBJECT_RESOLVER_FACTORY_HPP
+#define MATADOR_OBJECT_RESOLVER_FACTORY_HPP
+
+#include "matador/object/object_resolver.hpp"
+
+#include <unordered_map>
+
+namespace matador::object {
+class object_resolver_factory {
+public:
+  virtual ~object_resolver_factory() = default;
+
+  template<class Type>
+  std::shared_ptr<object_resolver<Type>> resolver() {
+    const auto res = acquire_resolver(std::type_index(typeid(Type)));
+    if (!res) {
+      return std::dynamic_pointer_cast<object_resolver<Type>>(res);
+    }
+
+    return std::dynamic_pointer_cast<object_resolver<Type>>(res);
+  }
+
+  virtual std::shared_ptr<abstract_object_resolver> acquire_resolver(const std::type_index &type) = 0;
+  virtual void register_resolver(std::shared_ptr<abstract_object_resolver> &&resolver) = 0;
+};
+}
+#endif //MATADOR_OBJECT_RESOLVER_FACTORY_HPP

include/matador/object/relation_completer.hpp

@@ -5,7 +5,6 @@
 #include "matador/object/foreign_node_completer.hpp"
 #include "matador/object/many_to_many_relation.hpp"
 #include "matador/object/join_columns_collector.hpp"
-#include "matador/object/object_ptr.hpp"
 #include "matador/object/repository_node.hpp"
 
 #include "matador/logger/log_manager.hpp"

include/matador/orm/session.hpp

@@ -2,8 +2,8 @@
 #define QUERY_SESSION_HPP
 
 #include "matador/orm/error_code.hpp"
-#include "matador/orm/session_query_builder.hpp"
 
+#include "matador/query/query_builder.hpp"
 #include "matador/query/criteria.hpp"
 #include "matador/query/query.hpp"
 #include "matador/query/generator.hpp"
@@ -18,34 +18,30 @@
 #include "matador/object/object_ptr.hpp"
 
 #include <unordered_map>
+#include <utility>
 
 namespace matador::orm {
-
 utils::error make_error(error_code ec, const std::string &msg);
 
 struct session_context {
-  utils::message_bus &bus;
+  session_context(utils::message_bus &bus, std::string dns, const size_t count, const size_t cache_size = 500)
-  sql::connection_pool &pool;
+  : bus(bus)
-  size_t cache_size{500};
+  , dns(std::move(dns))
-};
+  , connection_count(count)
-
+  , cache_size(cache_size) {
-template<typename Type>
-class lazy_object_resolver final : public object::object_resolver<Type> {
-public:
-    explicit lazy_object_resolver(sql::statement &&stmt) : stmt_(std::move(stmt)) {}
-
-    Type* resolve(const object::object_proxy<Type>& proxy) const override {
-        return proxy.resolve();
   }
-
+  utils::message_bus &bus;
-private:
+  std::string dns;
-    sql::statement stmt_;
+  size_t connection_count{};
+  size_t cache_size{500};
+  std::shared_ptr<sql::producer_resolver_factory> resolver_factory = std::make_shared<sql::producer_resolver_factory>();
 };
 
 class prototype_builder final {
 public:
   explicit prototype_builder(const std::unordered_map<std::string, sql::statement> &statements_per_column)
-  : statements_per_column_(statements_per_column) {}
+  : statements_per_column_(statements_per_column) {
+  }
 
 
   template<typename Type>
@@ -57,31 +53,48 @@ public:
   }
 
   template<class V>
-  static void on_primary_key(const char * /*id*/, V &/*pk*/, const utils::primary_key_attribute& /*attr*/ = utils::default_pk_attributes) {}
+  static void on_primary_key(const char * /*id*/, V &/*pk*/,
-  static void on_revision(const char * /*id*/, uint64_t &/*rev*/) {}
+                             const utils::primary_key_attribute & /*attr*/ = utils::default_pk_attributes) {
+  }
+
+  static void on_revision(const char * /*id*/, uint64_t &/*rev*/) {
+  }
+
   template<typename Type>
-  static void on_attribute(const char * /*id*/, Type &/*obj*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
+  static void on_attribute(const char * /*id*/, Type &/*obj*/,
+                           const utils::field_attributes &/*attr*/ = utils::null_attributes) {
+  }
+
   template<class Pointer>
   void on_belongs_to(const char *id, Pointer &/*obj*/, const utils::foreign_attributes &/*attr*/) {
     const auto it = statements_per_column_.find(id);
     if (it == statements_per_column_.end()) {
       return;
     }
-
-
   }
+
   template<class Pointer>
-  void on_has_one(const char * /*id*/, Pointer &/*obj*/, const utils::foreign_attributes &/*attr*/) {}
+  void on_has_one(const char * /*id*/, Pointer &/*obj*/, const utils::foreign_attributes &/*attr*/) {
+  }
+
   template<class ContainerType>
-  void on_has_many(const char * /*id*/, ContainerType &, const char * /*join_column*/, const utils::foreign_attributes &/*attr*/) {}
+  void on_has_many(const char * /*id*/, ContainerType &, const char * /*join_column*/,
+                   const utils::foreign_attributes &/*attr*/) {
+  }
+
   template<class ContainerType>
-  void on_has_many_to_many(const char * /*id*/, ContainerType &/*cont*/, const char * /*join_column*/, const char * /*inverse_join_column*/, const utils::foreign_attributes &/*attr*/) {}
+  void on_has_many_to_many(const char * /*id*/, ContainerType &/*cont*/, const char * /*join_column*/,
+                           const char * /*inverse_join_column*/, const utils::foreign_attributes &/*attr*/) {
+  }
+
   template<class ContainerType>
-  void on_has_many_to_many(const char * /*id*/, ContainerType &/*cont*/, const utils::foreign_attributes &/*attr*/) {}
+  void on_has_many_to_many(const char * /*id*/, ContainerType &/*cont*/, const utils::foreign_attributes &/*attr*/) {
+  }
 
 private:
   const std::unordered_map<std::string, sql::statement> &statements_per_column_;
 };
+
 class session final : public sql::executor {
 public:
   session(session_context &&ctx, const query::schema &scm);
@@ -95,6 +108,8 @@ public:
    */
   template<typename Type>
   utils::result<object::object_ptr<Type>, utils::error> insert(Type *obj);
+  template<typename Type>
+  utils::result<object::object_ptr<Type>, utils::error> insert(object::object_ptr<Type> obj);
   template<class Type, typename... Args>
   utils::result<object::object_ptr<Type>, utils::error> insert(Args &&... args);
 
@@ -112,33 +127,40 @@ public:
   utils::result<void, utils::error> drop_table() const;
   utils::result<void, utils::error> drop_table(const std::string &table_name) const;
 
-  [[nodiscard]] utils::result<sql::query_result<sql::record>, utils::error> fetch_all(const sql::query_context &q) const;
+  [[nodiscard]] utils::result<sql::query_result<sql::record>, utils::error>
+  fetch_all(const sql::query_context &q) const;
   [[nodiscard]] utils::result<size_t, utils::error> execute(const std::string &sql) const;
 
   [[nodiscard]] std::vector<object::attribute> describe_table(const std::string &table_name) const;
   [[nodiscard]] bool table_exists(const std::string &table_name) const;
 
-  [[nodiscard]] utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> fetch(const sql::query_context &ctx) const override;
+  [[nodiscard]] utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> fetch(
+    const sql::query_context &ctx) const override;
   [[nodiscard]] utils::result<size_t, utils::error> execute(const sql::query_context &ctx) const override;
   [[nodiscard]] utils::result<sql::statement, utils::error> prepare(const sql::query_context &ctx) override;
   [[nodiscard]] std::string str(const sql::query_context &ctx) const override;
   [[nodiscard]] const sql::dialect &dialect() const override;
+  [[nodiscard]] std::shared_ptr<sql::producer_resolver_factory> resolver_factory() const override;
+  [[nodiscard]] const class query::basic_schema &schema() const;
 
 private:
   friend class query_select;
 
-  static query::fetchable_query build_select_query(entity_query_data &&data);
+  static query::fetchable_query build_select_query(query::entity_query_data &&data);
 
 private:
+  sql::connection_pool pool_;
   mutable sql::statement_cache cache_;
   const sql::dialect &dialect_;
 
-  const query::schema& schema_;
+  const query::basic_schema &schema_;
   mutable std::unordered_map<std::string, std::vector<object::attribute> > prototypes_;
+  std::shared_ptr<sql::producer_resolver_factory> resolver_factory_;
 };
 
 template<typename Type>
 utils::result<object::object_ptr<Type>, utils::error> session::insert(Type *obj) {
+  std::shared_ptr<Type> ptr(obj);
   const auto it = schema_.find(typeid(Type));
   if (it == schema_.end()) {
     return utils::failure(make_error(error_code::UnknownType, "Failed to determine requested type."));
@@ -155,7 +177,28 @@ utils::result<object::object_ptr<Type>, utils::error> session::insert(Type *obj)
   if (const auto insert_result = res->bind(*obj).execute(); !insert_result.is_ok()) {
     return utils::failure(insert_result.err());
   }
-  return utils::ok(object::object_ptr{obj});
+  return utils::ok(object::object_ptr{ptr});
+}
+
+template<typename Type>
+utils::result<object::object_ptr<Type>, utils::error> session::insert(object::object_ptr<Type> obj) {
+  const auto it = schema_.find(typeid(Type));
+  if (it == schema_.end()) {
+    return utils::failure(make_error(error_code::UnknownType, "Failed to determine requested type."));
+  }
+
+  auto res = query::query::insert()
+    .into(it->second.name(), query::generator::columns<Type>(schema_))
+    .values(query::generator::placeholders<Type>())
+    .prepare(*this);
+  if (!res) {
+    return utils::failure(res.err());
+  }
+
+  if (const auto insert_result = res->bind(*obj).execute(); !insert_result.is_ok()) {
+    return utils::failure(insert_result.err());
+  }
+  return utils::ok(obj);
 }
 
 template<class Type, typename... Args>
@@ -165,9 +208,10 @@ utils::result<object::object_ptr<Type>, utils::error> session::insert( Args&&...
 
 class pk_object_binder final {
 public:
-    explicit pk_object_binder(sql::statement &stmt, size_t position)
+  explicit pk_object_binder(sql::statement &stmt, const size_t position)
   : stmt_(stmt)
-    , binding_position_(position){}
+  , binding_position_(position) {
+  }
 
   template<class Type>
   sql::statement &bind(Type &obj) {
@@ -180,7 +224,9 @@ public:
     stmt_.bind(binding_position_, x);
   }
 
-    static void on_revision(const char * /*id*/, uint64_t &/*rev*/) {}
+  static void on_revision(const char * /*id*/, uint64_t &/*rev*/) {
+  }
+
   template<class Type>
   static void on_attribute(const char * /*id*/, Type &/*x*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
   template<class Pointer>
@@ -193,12 +239,14 @@ public:
                           ContainerType &/*c*/,
                           const char * /*join_column*/,
                           const utils::foreign_attributes &/*attr*/ = utils::CascadeNoneFetchLazy) {}
+
   template<class ContainerType>
   static void on_has_many_to_many(const char * /*id*/,
                                   ContainerType &/*c*/,
                                   const char * /*join_column*/,
                                   const char * /*inverse_join_column*/,
                                   const utils::foreign_attributes &/*attr*/) {}
+
   template<class ContainerType>
   static void on_has_many_to_many(const char * /*id*/,
                                   ContainerType &/*c*/,
@@ -207,7 +255,7 @@ public:
 private:
   sql::statement &stmt_;
   size_t binding_position_{0};
-    sql::object_pk_binder pk_binder_;
+  sql::object_pk_binder pk_binder_{};
 };
 
 template<typename Type>
@@ -268,19 +316,17 @@ utils::result<object::object_ptr<Type>, utils::error> session::find(const Primar
     return utils::failure(make_error(error_code::UnknownType, "Failed to determine requested type."));
   }
   const auto &info = it->second.node().info();
-    // if (!info) {
-        // return utils::failure(make_error(error_code::UnknownType, "Failed to determine requested type."));
-    // }
   if (!info.has_primary_key()) {
     return utils::failure(make_error(error_code::NoPrimaryKey, "Type hasn't primary key."));
   }
 
-    session_query_builder eqb(schema_, *this);
+  query::query_builder eqb(schema_, *this);
   const query::table_column c(&it->second.table(), info.primary_key_attribute()->name());
   using namespace matador::query;
   auto data = eqb.build<Type>(c == utils::_);
   if (!data.is_ok()) {
-        return utils::failure(make_error(error_code::FailedToBuildQuery, "Failed to build query for type " + info.name() + "."));
+    return utils::failure(make_error(error_code::FailedToBuildQuery,
+                                     "Failed to build query for type " + info.name() + "."));
   }
 
   auto res = build_select_query(data.release()).prepare(*this);
@@ -288,11 +334,14 @@ utils::result<object::object_ptr<Type>, utils::error> session::find(const Primar
   if (!res) {
     return utils::failure(res.err());
   }
-    auto stmt_result = res->bind(0, const_cast<PrimaryKeyType&>(pk)).template fetch_one<Type>();
+  auto stmt_result = res->bind(0, const_cast<PrimaryKeyType &>(pk))
-    if (stmt_result && !stmt_result.value()) {
+    .template fetch_one<Type>();
-        return utils::failure(make_error(error_code::FailedToFindObject, "Failed to find object of type " + info.name() + " with primary key " + std::to_string(pk) + "."));
+  if (!stmt_result) {
+    return utils::failure(make_error(error_code::FailedToFindObject,
+                                     "Failed to find object of type " + info.name() + " with primary key " +
+                                     std::to_string(pk) + "."));
   }
-    return utils::ok(object::object_ptr<Type>{ stmt_result->release() });
+  return utils::ok(*stmt_result);
 }
 
 template<typename Type>
@@ -302,10 +351,11 @@ utils::result<sql::query_result<Type>, utils::error> session::find(query::criter
     return utils::failure(make_error(error_code::UnknownType, "Failed to determine requested type."));
   }
 
-    session_query_builder eqb(schema_, *this);
+  query::query_builder eqb(schema_, *this);
   auto data = eqb.build<Type>(std::move(clause));
   if (!data.is_ok()) {
-        return utils::failure(make_error(error_code::FailedToBuildQuery, "Failed to build query for type " + it->second.name() + "."));
+    return utils::failure(make_error(error_code::FailedToBuildQuery,
+                                     "Failed to build query for type " + it->second.name() + "."));
   }
 
   auto result = build_select_query(data.release()).prepare(*this);

include/matador/query/basic_schema.hpp

@@ -0,0 +1,64 @@
+#ifndef MATADOR_BASIC_SCHEMA_HPP
+#define MATADOR_BASIC_SCHEMA_HPP
+
+#include "matador/object/repository.hpp"
+
+#include "matador/sql/producer_resolver_factory.hpp"
+
+#include "matador/query/table.hpp"
+
+#include <unordered_map>
+#include <memory>
+#include <typeindex>
+
+namespace matador::query {
+class schema_node final {
+public:
+  schema_node(class table tab, const object::repository_node& node);
+
+  [[nodiscard]] const std::string& name() const;
+  [[nodiscard]] const class table& table() const;
+  [[nodiscard]] const object::repository_node& node() const;
+
+private:
+  class table table_;
+  const object::repository_node& node_;
+};
+
+class basic_schema {
+public:
+  using schema_node_map = std::unordered_map<std::type_index, schema_node>;
+  using iterator = std::unordered_map<std::type_index, schema_node>::iterator;
+  using const_iterator = std::unordered_map<std::type_index, schema_node>::const_iterator;
+
+  basic_schema();
+  explicit basic_schema(const std::string &name);
+
+  iterator begin();
+  iterator end();
+  [[nodiscard]] const_iterator begin() const;
+  [[nodiscard]] const_iterator end() const;
+
+  [[nodiscard]] size_t size() const;
+  [[nodiscard]] bool empty() const;
+
+  iterator find(const std::type_index& ti);
+  iterator find(const std::string& name);
+
+  [[nodiscard]] const_iterator find(const std::type_index& ti) const;
+  [[nodiscard]] const_iterator find(const std::string& name) const;
+
+  [[nodiscard]] bool contains(const std::type_index &index) const;
+
+  void initialize_executor(sql::executor &exec) const;
+
+protected:
+  template<typename Type>
+  friend class schema_observer;
+
+  object::repository repo_;
+  std::unordered_map<std::type_index, schema_node> schema_nodes_;
+  std::unordered_map<std::type_index, std::unique_ptr<sql::resolver_producer>> resolver_producers_;
+};
+}
+#endif //MATADOR_BASIC_SCHEMA_HPP

include/matador/query/criteria/criteria_operators.hpp

@@ -7,6 +7,9 @@
 #include "matador/utils/placeholder.hpp"
 #include "matador/utils/value.hpp"
 
+namespace matador::utils {
+class identifier;
+}
 namespace matador::sql {
 struct query_context;
 }
@@ -57,6 +60,9 @@ criteria_ptr operator>=(const table_column &col, utils::placeholder p);
 criteria_ptr operator<(const table_column &col, utils::placeholder p);
 criteria_ptr operator<=(const table_column &col, utils::placeholder p);
 
+criteria_ptr operator==(const table_column &col, const utils::identifier &id);
+criteria_ptr operator!=(const table_column &col, const utils::identifier &id);
+
 criteria_ptr operator&&(criteria_ptr left, criteria_ptr right);
 
 criteria_ptr operator||(criteria_ptr left, criteria_ptr right);

include/matador/query/generator.hpp

@@ -10,7 +10,7 @@
 #include "matador/query/internal/column_value_pair.hpp"
 
 #include "matador/query/table.hpp"
-#include "matador/query/schema.hpp"
+#include "matador/query/basic_schema.hpp"
 
 #include <vector>
 
@@ -45,7 +45,7 @@ constexpr auto default_column_generator_options = column_generator_options::Forc
 
 class column_generator {
 public:
-  explicit column_generator(const schema &repo,
+  explicit column_generator(const basic_schema &repo,
                             const table* tab,
                             column_generator_options options = default_column_generator_options);
 
@@ -141,7 +141,7 @@ private:
   void push(const std::string &column_name);
 
 private:
-  const schema &repo_;
+  const basic_schema &repo_;
   std::vector<table_column> result_;
   std::stack<const table*> table_stack_;
   std::unordered_set<std::string> seen_tables;
@@ -289,7 +289,7 @@ std::vector<internal::column_value_pair> column_value_pairs() {
 }
 
 template<typename Type>
-std::vector<table_column> columns(const schema &repo,
+std::vector<table_column> columns(const basic_schema &repo,
                             const table &tab,
                             const column_generator_options options = default_column_generator_options) {
     column_generator generator(repo, &tab, options);
@@ -297,7 +297,7 @@ std::vector<table_column> columns(const schema &repo,
 }
 
 template<typename Type>
-std::vector<table_column> columns(const schema &repo,
+std::vector<table_column> columns(const basic_schema &repo,
                                   const column_generator_options options = default_column_generator_options) {
   const auto it = repo.find(typeid(Type));
   if (it == repo.end()) {
@@ -309,7 +309,7 @@ std::vector<table_column> columns(const schema &repo,
 
 template<typename Type>
 std::vector<table_column> columns(const Type &obj,
-                                  const schema &repo,
+                                  const basic_schema &repo,
                                   const column_generator_options options = default_column_generator_options) {
   const auto it = repo.find(typeid(Type));
   if (it == repo.end()) {

include/matador/query/intermediates/fetchable_query.hpp

@@ -3,13 +3,15 @@
 
 #include "query_intermediate.hpp"
 
-#include "../query_compiler.hpp"
+#include "matador/query/query_compiler.hpp"
+#include "matador/sql/executor.hpp"
 
-#include "../../sql/query_result.hpp"
+#include "matador/sql/query_result.hpp"
-#include "../../sql/record.hpp"
+#include "matador/sql/query_record_result.hpp"
+#include "matador/sql/record.hpp"
 
-#include "../../utils/error.hpp"
+#include "matador/utils/error.hpp"
-#include "../../utils/result.hpp"
+#include "matador/utils/result.hpp"
 
 namespace matador::sql {
 class executor;
@@ -32,14 +34,15 @@ public:
     }
 
     const auto prototype = result.value()->prototype();
-    return utils::ok(sql::query_result<Type>(result.release(), [prototype] {
+    auto resolver = exec.resolver_factory()->resolver<Type>();
+    return utils::ok(sql::query_result<Type>(result.release(), resolver, [prototype] {
       return sql::detail::create_prototype<Type>(prototype);
     }));
   }
   [[nodiscard]] utils::result<sql::query_result<sql::record>, utils::error> fetch_all(const sql::executor &exec) const;
 
   template < class Type >
-  utils::result<std::unique_ptr<Type>, utils::error> fetch_one(const sql::executor &exec)
+  utils::result<object::object_ptr<Type>, utils::error> fetch_one(sql::executor &exec)
   {
     auto result = fetch(exec);
     if (!result.is_ok()) {
@@ -47,15 +50,16 @@ public:
     }
 
     const auto prototype = result.value()->prototype();
-    auto objects = sql::query_result<Type>(result.release(), [prototype] {
+    auto resolver = exec.resolver_factory()->resolver<Type>();
+    auto objects = sql::query_result<Type>(result.release(), resolver, [prototype] {
       return sql::detail::create_prototype<Type>(prototype);
     });
     auto first = objects.begin();
     if (first == objects.end()) {
-      return utils::ok(std::unique_ptr<Type>{nullptr});
+      return utils::ok(object::object_ptr<Type>{});
     }
 
-    return utils::ok(std::unique_ptr<Type>{first.release()});
+    return utils::ok(first.optr());
   }
 
   [[nodiscard]] utils::result<std::optional<sql::record>, utils::error> fetch_one(const sql::executor &exec) const;

include/matador/query/intermediates/query_insert_intermediate.hpp

@@ -3,10 +3,10 @@
 
 #include "matador/query/intermediates/query_intermediate.hpp"
 #include "matador/query/intermediates/query_into_intermediate.hpp"
-#include "matador/query/schema.hpp"
 #include "matador/query/generator.hpp"
 
 namespace matador::query {
+class schema;
 
 class query_insert_intermediate : public query_intermediate {
 public:

include/matador/query/query.hpp

@@ -4,13 +4,12 @@
 #include "matador/query/query_intermediates.hpp"
 
 #include "matador/query/generator.hpp"
-#include "matador/query/schema.hpp"
 
 namespace matador::sql {
 class connection;
 }
 namespace matador::query {
-
+class schema;
 table_column alias(const std::string &column, const std::string &as);
 table_column alias(table_column &&col, const std::string &as);
 table_column count(const std::string &column);

include/matador/query/query_builder.hpp

@@ -1,13 +1,11 @@
 #ifndef QUERY_ENTITY_QUERY_BUILDER_HPP
 #define QUERY_ENTITY_QUERY_BUILDER_HPP
 
-#include "matador/orm/query_builder_exception.hpp"
+#include "matador/query/query_builder_exception.hpp"
 
 #include "matador/query/criteria.hpp"
 #include "matador/query/query.hpp"
-#include "matador/query/schema.hpp"
 
-#include "matador/sql/executor.hpp"
 #include "matador/sql/statement.hpp"
 
 #include "matador/object/join_columns_collector.hpp"
@@ -21,45 +19,45 @@
 #include <stack>
 #include <unordered_map>
 
-namespace matador::orm {
+namespace matador::query {
 
 struct entity_query_data {
-  const query::table* root_table{nullptr};
+  const table* root_table{nullptr};
   std::string pk_column_name{};
-  std::vector<query::table_column> columns{};
+  std::vector<table_column> columns{};
   std::unordered_map<std::string, sql::statement> lazy_loading_statements{};
-  std::vector<query::join_data> joins{};
+  std::vector<join_data> joins{};
-  query::criteria_ptr where_clause{};
+  criteria_ptr where_clause{};
 };
 
-class criteria_transformer final : public query::criteria_visitor {
+class criteria_transformer final : public criteria_visitor {
 public:
-    criteria_transformer(const query::schema &repo, const std::unordered_map<std::string, query::table>& tables_by_name);
+    criteria_transformer(const basic_schema &repo, const std::unordered_map<std::string, table>& tables_by_name);
-    void visit( const query::between_criteria& node ) override;
+    void visit( const between_criteria& node ) override;
-    void visit( const query::binary_criteria& node ) override;
+    void visit( const binary_criteria& node ) override;
-    void visit( const query::binary_column_criteria& node ) override;
+    void visit( const binary_column_criteria& node ) override;
-    void visit( const query::collection_criteria& node ) override;
+    void visit( const collection_criteria& node ) override;
-    void visit( const query::collection_query_criteria& node ) override;
+    void visit( const collection_query_criteria& node ) override;
-    void visit( const query::like_criteria& node ) override;
+    void visit( const like_criteria& node ) override;
-    void visit( const query::logical_criteria& node ) override;
+    void visit( const logical_criteria& node ) override;
-    void visit( const query::not_criteria& node ) override;
+    void visit( const not_criteria& node ) override;
 
 private:
-    void update_criteria_column(const query::abstract_column_criteria& node) const;
+    void update_criteria_column(const abstract_column_criteria& node) const;
 
 private:
-    const query::schema &repo_;
+    const basic_schema &repo_;
-    const std::unordered_map<std::string, query::table>& tables_by_name_;
+    const std::unordered_map<std::string, table>& tables_by_name_;
 };
 
-class session_query_builder final {
+class query_builder final {
 public:
-  session_query_builder(const query::schema &scm, sql::executor &exec)
+  query_builder(const basic_schema &scm, sql::executor &exec)
   : schema_(scm)
   , executor_(exec){}
 
   template<class EntityType>
-  utils::result<entity_query_data, query_build_error> build(query::criteria_ptr clause = {}) {
+  utils::result<entity_query_data, query_build_error> build(criteria_ptr clause = {}) {
     const auto it = schema_.find(typeid(EntityType));
     if (it == schema_.end()) {
       return utils::failure(query_build_error::UnknownType);
@@ -144,8 +142,8 @@ public:
     }
 
     append_join(
-      query::table_column{&table_info_stack_.top().table, table_info_stack_.top().info.primary_key_attribute()->name()},
+      table_column{&table_info_stack_.top().table, table_info_stack_.top().info.primary_key_attribute()->name()},
-      query::table_column{&next->second, join_column}
+      table_column{&next->second, join_column}
     );
 
 
@@ -159,7 +157,7 @@ public:
       // if (next != processed_tables_.end()) {
       //   return;
       // }
-      // table_info_stack_.push({*result, std::make_shared<query::table>(info.name(), build_alias('t', ++table_index))});
+      // table_info_stack_.push({*result, std::make_shared<table>(info.name(), build_alias('t', ++table_index))});
       // next = processed_tables_.insert({info.name(), table_info_stack_.top().table}).first;
       // typename ContainerType::value_type::value_type obj;
       // access::process(*this , obj);
@@ -170,8 +168,8 @@ public:
       // }
       //
       // append_join(
-      //   query::column{table_info_stack_.top().table.get(), table_info_stack_.top().info.get().primary_key_attribute()->name()},
+      //   column{table_info_stack_.top().table.get(), table_info_stack_.top().info.get().primary_key_attribute()->name()},
-      //   query::column{next->second.get(), join_column}
+      //   column{next->second.get(), join_column}
       // );
   }
 
@@ -210,12 +208,12 @@ public:
     }
 
     append_join(
-      query::table_column{&table_info_stack_.top().table, table_info_stack_.top().info.primary_key_attribute()->name()},
+      table_column{&table_info_stack_.top().table, table_info_stack_.top().info.primary_key_attribute()->name()},
-      query::table_column{&relation->second, join_column}
+      table_column{&relation->second, join_column}
     );
     append_join(
-      query::table_column{&relation->second, inverse_join_column},
+      table_column{&relation->second, inverse_join_column},
-      query::table_column{&next->second, result->second.node().info().primary_key_attribute()->name()}
+      table_column{&next->second, result->second.node().info().primary_key_attribute()->name()}
     );
   }
 
@@ -257,12 +255,12 @@ public:
     const auto join_columns = join_columns_collector_.collect<typename ContainerType::value_type::value_type>();
 
     append_join(
-      query::table_column{&table_info_stack_.top().table, table_info_stack_.top().info.primary_key_attribute()->name()},
+      table_column{&table_info_stack_.top().table, table_info_stack_.top().info.primary_key_attribute()->name()},
-      query::table_column{&relation->second, join_columns.inverse_join_column}
+      table_column{&relation->second, join_columns.inverse_join_column}
     );
     append_join(
-      query::table_column{&relation->second, join_columns.join_column},
+      table_column{&relation->second, join_columns.join_column},
-      query::table_column{&next->second, result->second.node().info().primary_key_attribute()->name()}
+      table_column{&next->second, result->second.node().info().primary_key_attribute()->name()}
     );
   }
 
@@ -272,17 +270,17 @@ private:
   void push(const std::string &column_name);
   static std::string build_alias(char prefix, unsigned int count);
   [[nodiscard]] bool is_root_entity() const;
-  void append_join(const query::table_column &left, const query::table_column &right);
+  void append_join(const table_column &left, const table_column &right);
 
 private:
   struct table_info {
     const object::basic_object_info &info;
-    query::table table;
+    class table table;
   };
 
   std::stack<table_info> table_info_stack_{};
-  std::unordered_map<std::string, query::table> processed_tables_{};
+  std::unordered_map<std::string, table> processed_tables_{};
-  const query::schema &schema_;
+  const basic_schema &schema_;
   entity_query_data entity_query_data_{};
   unsigned int column_index{0};
   unsigned int table_index{0};
@@ -291,7 +289,7 @@ private:
 };
 
 template<class Pointer>
-void session_query_builder::on_foreign_object(const char *id, Pointer &, const utils::foreign_attributes &attr) {
+void query_builder::on_foreign_object(const char *id, Pointer &, const utils::foreign_attributes &attr) {
   const auto it = schema_.find(typeid(typename Pointer::value_type));
   if (it == schema_.end()) {
     throw query_builder_exception{query_build_error::UnknownType};
@@ -315,15 +313,15 @@ void session_query_builder::on_foreign_object(const char *id, Pointer &, const u
     table_info_stack_.pop();
 
     append_join(
-      query::table_column{&table_info_stack_.top().table, id},
+      table_column{&table_info_stack_.top().table, id},
-      query::table_column{&next->second, info.primary_key_attribute()->name()}
+      table_column{&next->second, info.primary_key_attribute()->name()}
     );
   } else {
     push(id);
     using namespace matador::utils;
     using namespace matador::query;
     // create select query
-    auto result = matador::query::query::select(generator::columns<typename Pointer::value_type>(schema_, foreign_table, generator::column_generator_options::ForceLazy))
+    auto result = query::query::select(generator::columns<typename Pointer::value_type>(schema_, foreign_table, generator::column_generator_options::ForceLazy))
       .from(foreign_table)
       .where(table_column(&foreign_table, info.primary_key_attribute()->name(), "") == _)
       .prepare(executor_);

include/matador/query/query_builder_exception.hpp

@@ -5,7 +5,7 @@
 
 #include <cstdint>
 
-namespace matador::orm {
+namespace matador::query {
 
 enum class query_build_error : std::uint8_t {
   Ok = 0,
@@ -17,7 +17,7 @@ enum class query_build_error : std::uint8_t {
 
 class query_builder_exception final : public std::exception {
 public:
-  explicit query_builder_exception(const query_build_error error, utils::error &&err = {});
+  explicit query_builder_exception(query_build_error error, utils::error &&err = {});
 
   [[nodiscard]] query_build_error error_type() const;
   [[nodiscard]] const utils::error &error() const;

include/matador/query/query_object_resolver.hpp

@@ -0,0 +1,62 @@
+#ifndef MATADOR_QUERY_OBJECT_LOADER_HPP
+#define MATADOR_QUERY_OBJECT_LOADER_HPP
+
+#include "matador/sql/internal/identifier_statement_binder.hpp"
+#include "matador/sql/statement.hpp"
+
+#include "matador/object/object_resolver.hpp"
+
+#include "matador/query/table.hpp"
+#include "matador/query/query_builder.hpp"
+
+namespace matador::sql {
+class executor;
+}
+
+namespace matador::query {
+template<typename Type>
+class query_object_resolver : public object::object_resolver<Type> {
+public:
+  explicit query_object_resolver(const basic_schema &repo, sql::executor& exec, const table &tab, std::string pk_name)
+  : executor_(exec)
+  , schema_(repo)
+  , table_(tab)
+  , pk_name_(std::move(pk_name)) {}
+
+  std::shared_ptr<Type> resolve(const utils::identifier &id) override;
+protected:
+  sql::executor& executor_;
+  const basic_schema &schema_;
+  const table &table_;
+  std::string pk_name_;
+  std::type_index index{typeid(Type)};
+};
+
+utils::result<sql::statement, utils::error> prepare_statement(sql::executor& exec, entity_query_data &&data);
+
+template<typename Type>
+std::shared_ptr<Type> query_object_resolver<Type>::resolve(const utils::identifier &id) {
+  query_builder qb(schema_, executor_);
+  const auto *pk_column = table_[pk_name_];
+  auto builder_result = qb.build<Type>(*pk_column == utils::_);
+
+  if (!builder_result) {
+    return nullptr;
+  }
+  auto stmt = prepare_statement(executor_, builder_result.release());
+  if (!stmt) {
+    return nullptr;
+  }
+
+  sql::identifier_statement_binder binder(*stmt);
+  binder.bind(id);
+
+  auto result = stmt->template fetch_one_raw<Type>();
+  if (!result) {
+    return nullptr;
+  }
+  return *result;
+}
+
+}
+#endif //MATADOR_QUERY_OBJECT_LOADER_HPP

include/matador/query/schema.hpp

@@ -2,19 +2,41 @@
 #define MATADOR_SCHEMA_HPP
 
 #include "matador/object/observer.hpp"
-#include "matador/object/repository.hpp"
 
 #include "matador/sql/query_context.hpp"
+#include "matador/sql/internal/resolver_producer.hpp"
 
-#include "matador/query/table.hpp"
+#include "matador/query/query_object_resolver.hpp"
+#include "matador/query/basic_schema.hpp"
 
 namespace matador::sql {
 class connection_pool;
 class connection;
+class executor;
 }
 
 namespace matador::query {
 
+template<typename Type>
+class query_resolver_producer : public sql::resolver_producer {
+public:
+  query_resolver_producer() = default;
+  query_resolver_producer(const basic_schema& repo, const table& tab, std::string pk_name)
+  : resolver_producer(typeid(Type))
+  , repo_(repo)
+  , table_(tab)
+  , pk_name_(std::move(pk_name)) {}
+
+  std::shared_ptr<object::abstract_object_resolver> produce(sql::executor &exec) override {
+    return std::make_shared<query_object_resolver<Type>>(repo_, exec, table_, std::move(pk_name_));
+  }
+
+private:
+  const basic_schema& repo_;
+  const table& table_;
+  std::string pk_name_;
+};
+
 class schema;
 
 using schema_ref = std::reference_wrapper<schema>;
@@ -52,25 +74,14 @@ private:
   schema& schema_;
 };
 
-class schema_node final {
+class schema final : public basic_schema {
 public:
-  schema_node(class table tab, const object::repository_node& node);
+  using basic_schema::basic_schema;
+  using basic_schema::iterator;
+  using basic_schema::const_iterator;
+  using basic_schema::contains;
+  using basic_schema::find;
 
-  [[nodiscard]] const std::string& name() const;
-  [[nodiscard]] const class table& table() const;
-  [[nodiscard]] const object::repository_node& node() const;
-
-private:
-  class table table_;
-  const object::repository_node& node_;
-};
-class schema final {
-public:
-  using iterator = std::unordered_map<std::type_index, schema_node>::iterator;
-  using const_iterator = std::unordered_map<std::type_index, schema_node>::const_iterator;
-
-  schema() = default;
-  explicit schema(const std::string &name);
 
   template<typename Type, typename... Observers>
   [[nodiscard]] utils::result<void, utils::error> attach(const std::string &name, Observers&&... observers) {
@@ -97,28 +108,15 @@ public:
   [[nodiscard]] static utils::result<std::vector<object::attribute>, utils::error> describe_table(const std::string &table_name, const sql::connection &conn) ;
   [[nodiscard]] utils::result<bool, utils::error> table_exists(const std::string &table_name, const sql::connection &conn) const;
 
-  iterator begin();
+  template<typename Type>
-  iterator end();
+  iterator find() { return basic_schema::find(typeid(Type)); }
-  const_iterator begin() const;
-  const_iterator end() const;
-
-  [[nodiscard]] size_t size() const;
-  [[nodiscard]] bool empty() const;
 
   template<typename Type>
-  iterator find() { return find(typeid(Type)); }
+  const_iterator find() const { return basic_schema::find(typeid(Type)); }
-  iterator find(const std::type_index& ti);
-  iterator find(const std::string& name);
 
-  template<typename Type>
-  const_iterator find() const { return find(typeid(Type)); }
-  const_iterator find(const std::type_index& ti) const;
-  const_iterator find(const std::string& name) const;
-
-  [[nodiscard]] bool contains(const std::type_index &index) const;
   template < typename Type >
   [[nodiscard]] bool contains() const {
-    return contains(std::type_index(typeid(Type)));
+    return basic_schema::contains(std::type_index(typeid(Type)));
   }
 
   const object::repository &repo() const { return repo_; }
@@ -130,14 +128,11 @@ private:
   [[nodiscard]] static sql::query_context build_add_constraint_context(const object::repository_node& node, const object::restriction& cons, const sql::connection &conn) ;
   [[nodiscard]] static sql::query_context build_drop_constraint_context(const object::repository_node& node, const object::restriction& cons, const sql::connection &conn) ;
 
-  void insert_table(const std::type_index& ti, const object::repository_node &node);
+  iterator insert_table(const std::type_index& ti, const object::repository_node &node);
 
 private:
   template<typename Type>
   friend class schema_observer;
-
-  object::repository repo_;
-  std::unordered_map<std::type_index, schema_node> schema_nodes_;
 };
 
 template<typename Type>
@@ -151,7 +146,12 @@ utils::result<void, utils::error> schema::drop_table(const sql::connection &conn
 }
 template <typename Type>
 void schema_observer<Type>::on_attach(const object::repository_node &node, const Type &/*prototype*/) const {
-  schema_.insert_table(typeid(Type), node);
+  const auto it = schema_.insert_table(typeid(Type), node);
+
+  if (it->second.node().info().has_primary_key()) {
+    auto producer = std::make_unique<query_resolver_producer<Type>>(schema_, it->second.table(), it->second.node().info().primary_key_attribute()->name());
+    schema_.resolver_producers_[typeid(Type)] = std::move(producer);
+  }
 }
 
 template <typename Type>

include/matador/query/table_column.hpp

@@ -6,9 +6,7 @@
 #include "matador/utils/basic_types.hpp"
 #include "matador/utils/field_attributes.hpp"
 
-#include <memory>
 #include <string>
-#include <variant>
 
 namespace matador::query {
 

include/matador/sql/connection.hpp

@@ -25,7 +25,8 @@ public:
    * @param info The database connection info data
    * @param sql_logger The logging handler
    */
-  explicit connection(const connection_info& info, const logger_ptr &sql_logger = null_logger);
+  explicit connection(const connection_info& info, logger_ptr sql_logger = null_logger);
+  explicit connection(const connection_info& info, std::shared_ptr<producer_resolver_factory> resolver_factory, logger_ptr sql_logger = null_logger);
   /**
    * @brief Creates a database connection from a connection string.
    *
@@ -33,6 +34,7 @@ public:
    * @param sql_logger The logging handler
    */
   explicit connection(const std::string &dns, const logger_ptr &sql_logger = null_logger);
+  explicit connection(const std::string &dns, std::shared_ptr<producer_resolver_factory> resolver_factory, const logger_ptr &sql_logger = null_logger);
   /**
    * Copies a given connection
    *
@@ -138,6 +140,7 @@ public:
   [[nodiscard]] std::string str( const query_context& ctx ) const override;
 
   [[nodiscard]] const class dialect &dialect() const override;
+  [[nodiscard]] std::shared_ptr<producer_resolver_factory> resolver_factory() const override;
 
 private:
   [[nodiscard]] utils::result<std::unique_ptr<statement_impl>, utils::error> perform_prepare(const query_context &ctx) const;
@@ -149,6 +152,7 @@ private:
 
   std::unique_ptr<connection_impl> connection_;
   std::shared_ptr<abstract_sql_logger> logger_ = std::make_shared<null_sql_logger>();
+  std::shared_ptr<producer_resolver_factory> resolver_factory_ = std::make_shared<producer_resolver_factory>();
 };
 }
 

include/matador/sql/connection_pool.hpp

@@ -46,6 +46,7 @@ private:
 class connection_pool {
 public:
   connection_pool(const std::string &dns, size_t count);
+  connection_pool(const std::string &dns, size_t count, std::function<connection(const connection_info &)> &&connection_creator);
 
   connection_ptr acquire();
   connection_ptr try_acquire();
@@ -74,6 +75,7 @@ private:
   connection_map idle_connections_;
 
   const connection_info info_;
+  std::function<connection(const connection_info &)> connection_creator_;
 };
 
 }

include/matador/sql/executor.hpp

@@ -1,6 +1,8 @@
 #ifndef EXECUTOR_HPP
 #define EXECUTOR_HPP
 
+#include "matador/sql/producer_resolver_factory.hpp"
+
 #include "matador/utils/error.hpp"
 #include "matador/utils/result.hpp"
 
@@ -20,6 +22,7 @@ public:
   [[nodiscard]] virtual utils::result<std::unique_ptr<query_result_impl>, utils::error> fetch(const query_context &ctx) const = 0;
   [[nodiscard]] virtual utils::result<statement, utils::error> prepare(const query_context &ctx) = 0;
   [[nodiscard]] virtual std::string str(const query_context &ctx) const = 0;
+  [[nodiscard]] virtual std::shared_ptr<producer_resolver_factory> resolver_factory() const = 0;
 };
 
 }

include/matador/sql/field.hpp

@@ -28,6 +28,9 @@ public:
   field(field &&x) noexcept;
   field& operator=(field &&x) noexcept;
 
+  bool operator==(const field& rhs) const;
+  bool operator!=(const field& rhs) const;
+
   template<typename Type>
   field& operator=(Type value) {
     value_ = std::move(value);

include/matador/sql/interface/statement_impl.hpp

@@ -7,11 +7,13 @@
 #include "matador/sql/object_parameter_binder.hpp"
 
 #include "matador/utils/data_type_traits.hpp"
+#include "matador/utils/error.hpp"
+#include "matador/utils/result.hpp"
 
 #include <memory>
 
 namespace matador::sql {
-
+class query_result_impl;
 class sql_error;
 
 class statement_impl {

include/matador/sql/interface/statement_proxy.hpp

@@ -40,6 +40,8 @@ public:
   [[nodiscard]] std::unique_ptr<utils::attribute_writer> create_binder() const;
 
 protected:
+  friend class statement;
+
   std::unique_ptr<statement_impl> statement_;
 };
 

include/matador/sql/internal/identifier_reader.hpp

@@ -0,0 +1,51 @@
+#ifndef MATADOR_IDENTIFIER_READER_HPP
+#define MATADOR_IDENTIFIER_READER_HPP
+
+#include "matador/utils/access.hpp"
+#include "matador/utils/identifier.hpp"
+#include "matador/utils/primary_key_attribute.hpp"
+
+namespace matador::sql {
+class query_result_reader;
+}
+
+namespace matador::sql::internal {
+class identifier_reader final {
+public:
+  explicit identifier_reader(query_result_reader &reader);
+
+  template<class Type>
+  utils::identifier read(const Type &obj, const size_t column_index) {
+    identifier_.clear();
+    column_index_ = column_index;
+    access::process(*this, obj);
+    return identifier_;
+  }
+
+  template<typename ValueType>
+  void on_primary_key(const char *id, ValueType &value, const utils::primary_key_attribute& attr = utils::default_pk_attributes) {
+    utils::data_type_traits<ValueType>::read_value(reader_, id, column_index_, value, attr.size());
+    identifier_ = value;
+  }
+
+  static void on_revision(const char * /*id*/, uint64_t &/*rev*/) {}
+  template < class Type >
+  static void on_attribute(const char * /*id*/, Type &/*x*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
+  template < class Pointer >
+  static void on_belongs_to(const char * /*id*/, Pointer &/*x*/, const utils::foreign_attributes &/*attr*/) {}
+  template < class Pointer >
+  static void on_has_one(const char * /*id*/, Pointer &/*x*/, const utils::foreign_attributes &/*attr*/) {}
+  template<class ContainerType>
+  static void on_has_many(const char * /*id*/, ContainerType &, const char *, const utils::foreign_attributes &/*attr*/) {}
+  template<class ContainerType>
+  static void on_has_many_to_many(const char * /*id*/, ContainerType & /*c*/, const char * /*join_column*/, const char * /*inverse_join_column*/, const utils::foreign_attributes &/*attr*/) {}
+  template<class ContainerType>
+  static void on_has_many_to_many(const char * /*id*/, ContainerType & /*c*/, const utils::foreign_attributes &/*attr*/) {}
+
+private:
+  query_result_reader &reader_;
+  size_t column_index_{};
+  utils::identifier identifier_;
+};
+}
+#endif //MATADOR_IDENTIFIER_READER_HPP

include/matador/sql/internal/identifier_statement_binder.hpp

@@ -0,0 +1,33 @@
+#ifndef MATADOR_IDENTIFIER_STATEMENT_BINDER_HPP
+#define MATADOR_IDENTIFIER_STATEMENT_BINDER_HPP
+
+#include "matador/utils/identifier.hpp"
+
+namespace matador::sql {
+class statement;
+
+class identifier_statement_binder : public utils::identifier_serializer {
+public:
+  explicit identifier_statement_binder(statement &stmt, size_t index = 0);
+
+  void bind(const utils::identifier &id);
+
+  void serialize(int8_t &, const utils::field_attributes &) override;
+  void serialize(int16_t &, const utils::field_attributes &) override;
+  void serialize(int32_t &, const utils::field_attributes &) override;
+  void serialize(int64_t &, const utils::field_attributes &) override;
+  void serialize(uint8_t &, const utils::field_attributes &) override;
+  void serialize(uint16_t &, const utils::field_attributes &) override;
+  void serialize(uint32_t &, const utils::field_attributes &) override;
+  void serialize(uint64_t &, const utils::field_attributes &) override;
+  void serialize(const char *, const utils::field_attributes &) override;
+  void serialize(std::string &, const utils::field_attributes &) override;
+  void serialize(utils::null_type_t &, const utils::field_attributes &) override;
+
+private:
+  statement &stmt_;
+  size_t index_{};
+};
+
+}
+#endif //MATADOR_IDENTIFIER_STATEMENT_BINDER_HPP

include/matador/sql/internal/query_result_impl.hpp

@@ -10,16 +10,17 @@
 
 #include "matador/sql/interface/query_result_reader.hpp"
 #include "matador/sql/internal/query_result_pk_resolver.hpp"
+#include "matador/sql/internal/identifier_reader.hpp"
 #include "matador/sql/record.hpp"
 
 #include "matador/object/attribute.hpp"
+#include "matador/object/object_proxy.hpp"
+#include "matador/object/object_resolver_factory.hpp"
 
-#include <iostream>
 #include <memory>
 #include <stack>
 #include <string>
 #include <typeindex>
-#include <unordered_set>
 
 namespace matador::utils {
 class value;
@@ -73,9 +74,9 @@ private:
 class query_result_impl {
 public:
   query_result_impl(std::unique_ptr<query_result_reader> &&reader,
-                    std::vector<object::attribute> &&prototype, size_t column_index = 0);
+                    std::vector<object::attribute> prototype,
-  query_result_impl(std::unique_ptr<query_result_reader> &&reader,
+                    const std::shared_ptr<object::object_resolver_factory>& resolver_factory,
-                    const std::vector<object::attribute> &prototype, size_t column_index = 0);
+                    size_t column_index = 0);
 
   template<typename ValueType>
   void on_primary_key(const char *id, ValueType &value, const utils::primary_key_attribute& attr = utils::default_pk_attributes) {
@@ -122,17 +123,19 @@ public:
   }
 
   template<class ContainerType>
-  void on_has_many(const char * /*id*/, ContainerType &cont, const char * /*join_column*/,
+  void on_has_many(const char * /*id*/, ContainerType &cont, const char * /*join_column*/, const utils::foreign_attributes &attr) {
-                   const utils::foreign_attributes &attr) {
+    using value_type = typename ContainerType::value_type::value_type;
+    auto resolver = resolver_factory_->resolver<value_type>();
+
     if (attr.fetch() == utils::fetch_type::Lazy) {
       // pk_reader_.read(*id, column_index_++);
     } else {
-      const auto ti = std::type_index(typeid(typename ContainerType::value_type::value_type));
+      const auto ti = std::type_index(typeid(value_type));
-      auto obj = std::make_unique<typename ContainerType::value_type::value_type>();
+      auto obj = std::make_shared<typename ContainerType::value_type::value_type>();
       type_stack_.push(ti);
       access::process(*this, *obj);
       type_stack_.pop();
-      auto ptr = typename ContainerType::value_type(obj.release());
+      auto ptr = typename ContainerType::value_type(std::make_shared<object::object_proxy<value_type>>(resolver, obj));
       const auto pk = ptr.primary_key();
       if (ptr.primary_key().is_valid()) {
         cont.push_back(ptr);
@@ -194,16 +197,18 @@ private:
 
   template<class Pointer>
   void on_foreign_key(Pointer &x, const utils::foreign_attributes &attr) {
-    if (x.empty()) {
+    const auto resolver = resolver_factory_->resolver<typename Pointer::value_type>();
-      x.reset(new typename Pointer::value_type);
-    }
     if (attr.fetch() == utils::fetch_type::Lazy) {
-      pk_reader_.read(*x, column_index_++);
+      typename Pointer::value_type obj;
+      auto pk = id_reader_.read(obj, column_index_++);
+      x = Pointer(std::make_shared<object::object_proxy<typename Pointer::value_type>>(resolver, pk));
     } else {
+      auto obj = std::make_shared<typename Pointer::value_type>();
       const auto ti = std::type_index(typeid(*x));
       type_stack_.push(ti);
-      access::process(*this, *x);
+      access::process(*this, *obj);
       type_stack_.pop();
+      x = Pointer(std::make_shared<object::object_proxy<typename Pointer::value_type>>(resolver, obj));
     }
   }
 
@@ -211,6 +216,8 @@ protected:
   size_t column_index_ = 0;
   std::vector<object::attribute> prototype_;
   std::unique_ptr<query_result_reader> reader_;
+  std::shared_ptr<object::object_resolver_factory> resolver_factory_;
+  internal::identifier_reader id_reader_;
   detail::pk_reader pk_reader_;
   std::stack<std::type_index> type_stack_;
   utils::identifier current_pk_{};

include/matador/sql/internal/query_result_pk_resolver.hpp

@@ -50,9 +50,9 @@ public:
     template<class ContainerType>
     static void on_has_many(const char * /*id*/, ContainerType &, const char *, const utils::foreign_attributes &/*attr*/) {}
     template<class ContainerType>
-    static void on_has_many_to_many(const char *id, ContainerType &c, const char *join_column, const char *inverse_join_column, const utils::foreign_attributes &/*attr*/) {}
+    static void on_has_many_to_many(const char * /*id*/, ContainerType & /*c*/, const char * /*join_column*/, const char * /*inverse_join_column*/, const utils::foreign_attributes &/*attr*/) {}
     template<class ContainerType>
-    static void on_has_many_to_many(const char *id, ContainerType &c, const utils::foreign_attributes &/*attr*/) {}
+    static void on_has_many_to_many(const char * /*id*/, ContainerType & /*c*/, const utils::foreign_attributes &/*attr*/) {}
 
 private:
     template<class Type>
@@ -60,8 +60,8 @@ private:
         if (fetch == utils::fetch_type::Lazy) {
             ++column_index_;
         } else {
-            const Type obj;
+            const Type obj{};
-            type_stack_.push(typeid(Type));
+            type_stack_.emplace(typeid(Type));
             access::process(*this, obj);
             type_stack_.pop();
         }

include/matador/sql/internal/resolver_producer.hpp

@@ -0,0 +1,24 @@
+#ifndef MATADOR_RESOLVER_PRODUCER_HPP
+#define MATADOR_RESOLVER_PRODUCER_HPP
+
+#include "matador/object/object_resolver.hpp"
+
+#include <memory>
+
+namespace matador::sql {
+class executor;
+class resolver_producer {
+public:
+  virtual ~resolver_producer() = default;
+  virtual std::shared_ptr<object::abstract_object_resolver> produce(executor &exec) = 0;
+
+  [[nodiscard]] const std::type_index& type() const;
+
+protected:
+  explicit resolver_producer(const std::type_index &type);
+
+private:
+  std::type_index type_;
+};
+}
+#endif //MATADOR_RESOLVER_PRODUCER_HPP

include/matador/sql/internal/statement_object_resolver.hpp

@@ -0,0 +1,35 @@
+#ifndef MATADOR_STATEMENT_OBJECT_RESOLVER_HPP
+#define MATADOR_STATEMENT_OBJECT_RESOLVER_HPP
+
+#include "matador/object/object_resolver.hpp"
+
+#include "matador/sql/statement.hpp"
+#include "matador/sql/internal/identifier_statement_binder.hpp"
+
+namespace matador::sql {
+template<typename Type>
+class statement_object_resolver : public object::object_resolver<Type> {
+public:
+  explicit statement_object_resolver(statement stmt)
+  : statement_(std::move(stmt)) {}
+
+  std::shared_ptr<Type> resolve(const utils::identifier &id) override;
+protected:
+  statement statement_;
+  std::type_index index{typeid(Type)};
+};
+
+template<typename Type>
+std::shared_ptr<Type> statement_object_resolver<Type>::resolve(const utils::identifier &id) {
+  identifier_statement_binder binder(statement_);
+  binder.bind(id);
+
+  auto result = statement_.template fetch_one<Type>();
+  if (!result) {
+    return nullptr;
+  }
+  return std::make_shared<Type>(*result);
+}
+
+}
+#endif //MATADOR_STATEMENT_OBJECT_RESOLVER_HPP

include/matador/sql/producer_resolver_factory.hpp

@@ -0,0 +1,21 @@
+#ifndef MATADOR_RESOLVER_FACTORY_HPP
+#define MATADOR_RESOLVER_FACTORY_HPP
+
+#include "matador/object/object_resolver_factory.hpp"
+
+#include "matador/sql/internal/resolver_producer.hpp"
+
+namespace matador::sql {
+class executor;
+
+class producer_resolver_factory : public object::object_resolver_factory {
+public:
+
+  std::shared_ptr<object::abstract_object_resolver> acquire_resolver(const std::type_index &type) override;
+  void register_resolver(std::shared_ptr<object::abstract_object_resolver> &&resolver) override;
+
+private:
+  std::unordered_map<std::type_index, std::shared_ptr<object::abstract_object_resolver>> resolvers_;
+};
+}
+#endif //MATADOR_RESOLVER_FACTORY_HPP

include/matador/sql/query_context.hpp

@@ -2,13 +2,11 @@
 #define QUERY_QUERY_DATA_HPP
 
 #include "matador/object/attribute.hpp"
+#include "matador/object/object_resolver_factory.hpp"
 
 #include "matador/utils/types.hpp"
 
-#include <unordered_map>
-
 namespace matador::sql {
-
 enum class sql_command {
   SQL_UNKNOWN,
   SQL_CREATE,
@@ -40,14 +38,10 @@ struct query_context {
   std::string schema_name{};
   std::string table_name{};
   std::vector<object::attribute> prototype{};
-  // std::vector<std::string> result_vars{};
   std::vector<std::string> bind_vars{};
   std::vector<utils::database_type> bind_types{};
-
+  std::shared_ptr<object::object_resolver_factory> resolver_factory{};
-  // std::unordered_map<std::string, std::string> column_aliases{};
-  // std::unordered_map<std::string, std::string> table_aliases{};
 };
-
 }
 
 #endif //QUERY_QUERY_DATA_HPP

include/matador/sql/query_record_result.hpp

@@ -0,0 +1,132 @@
+#ifndef MATADOR_QUERY_RECORD_RESULT_HPP
+#define MATADOR_QUERY_RECORD_RESULT_HPP
+
+#include "matador/sql/query_result.hpp"
+
+namespace matador::sql {
+
+template <>
+class query_result<record>;
+
+template <>
+class query_result_iterator<record> {
+public:
+  using iterator_category = std::forward_iterator_tag;
+  using value_type = record;
+  using difference_type = std::ptrdiff_t;
+  using self = query_result_iterator;        /**< Shortcut for this class. */
+  using pointer = value_type*;               /**< Shortcut for the pointer type. */
+  using reference = value_type&;             /**< Shortcut for the reference type */
+
+public:
+  query_result_iterator() = default;
+  explicit query_result_iterator(query_result<record> *res)
+  : result_(res)
+  {}
+  query_result_iterator(query_result<record> *res, record rec)
+  : record_(std::move(rec))
+  , result_(res)
+  {}
+  query_result_iterator(query_result_iterator&& x) noexcept
+  : record_(std::move(x.record_))
+  , result_(x.result_)
+  {}
+  query_result_iterator& operator=(query_result_iterator&& x) noexcept {
+    result_ = x.result_;
+    record_ = std::move(x.record_);
+    return *this;
+  }
+
+  ~query_result_iterator() = default;
+
+  bool operator==(const query_result_iterator& rhs) const {
+    return record_ == rhs.record_;
+  }
+
+  bool operator!=(const query_result_iterator& rhs) const {
+    return !(*this == rhs);
+  }
+
+  self& operator++();
+  self operator++(int);
+
+  pointer operator->() { return &record_; }
+  reference operator*() { return record_; }
+  record release() { return std::move(record_); }
+
+private:
+  record record_;
+  query_result<record> *result_{nullptr};
+};
+
+template<>
+class query_result<record> final {
+public:
+  using iterator = query_result_iterator<record>;
+
+  query_result(std::unique_ptr<query_result_impl> &&impl, const std::vector<object::attribute> &prototype)
+  : impl_(std::move(impl))
+  , prototype_(prototype) {}
+
+  iterator begin() { return std::move(++iterator(this)); }
+  iterator end() { return {}; }
+
+private:
+  friend class query_result_iterator<record>;
+
+  [[nodiscard]] record create() const;
+  void bind(const record& obj) const;
+  bool fetch(record& obj) const;
+
+protected:
+  std::unique_ptr<query_result_impl> impl_;
+  std::vector<object::attribute> prototype_;
+};
+
+inline record query_result<record>::create() const {
+  record rec;
+  int index{0};
+  for (const auto &col: prototype_) {
+    rec.append({
+        col.name(),
+        col.type(),
+        col.attributes().options(),
+        col.attributes().size(),
+        index++
+    });
+  }
+  return rec;
+
+}
+
+inline void query_result<record>::bind(const record &obj) const {
+  impl_->bind(obj);
+}
+
+inline bool query_result<record>::fetch(record &obj) const {
+  return impl_->fetch(obj);
+}
+
+inline query_result_iterator<record>::self & query_result_iterator<record>::operator++() {
+  record_ = result_->create();
+  result_->bind(record_);
+  if (!result_->fetch(record_)) {
+    record_.clear();
+  }
+
+  return *this;
+}
+
+inline query_result_iterator<record>::self query_result_iterator<record>::operator++(int) {
+  self tmp(result_, record_);
+
+  record_ = result_->create();
+  result_->bind(record_);
+  if (!result_->fetch(record_)) {
+    record_.clear();
+  }
+
+  return tmp;
+}
+}
+#endif //MATADOR_QUERY_RECORD_RESULT_HPP

include/matador/sql/query_result.hpp

@@ -2,22 +2,24 @@
 #define QUERY_QUERY_RESULT_HPP
 
 #include "matador/object/attribute.hpp"
+#include "matador/object/object_ptr.hpp"
 
 #include "matador/sql/internal/query_result_impl.hpp"
 
 #include <functional>
 #include <memory>
 
-namespace matador::sql {
+#include "matador/object/object.hpp"
 
+namespace matador::sql {
 class record;
+class query_result_impl;
 
 template < typename Type >
 class query_result;
 
 template < typename Type >
-class query_result_iterator
+class query_result_iterator {
-{
 public:
   using iterator_category = std::forward_iterator_tag;
   using value_type = Type;
@@ -31,7 +33,7 @@ public:
   explicit query_result_iterator(query_result<Type> *res)
   : result_(res)
   {}
-  query_result_iterator(query_result<Type> *res, std::unique_ptr<Type> obj)
+  query_result_iterator(query_result<Type> *res, object::object_ptr<Type> obj)
   : obj_(std::move(obj))
   , result_(res)
   {}
@@ -48,19 +50,20 @@ public:
 
   ~query_result_iterator() = default;
 
-  bool operator==(const query_result_iterator& rhs) {
+  bool operator==(const query_result_iterator& rhs) const {
     return obj_ == rhs.obj_;
   }
 
-  bool operator!=(const query_result_iterator& rhs) {
+  bool operator!=(const query_result_iterator& rhs) const {
-    return obj_ != rhs.obj_;
+    return !operator==(rhs);
   }
 
   self& operator++() {
-    obj_.reset(result_->create());
+    auto obj = result_->create();
-    result_->bind(*obj_);
+    result_->bind(*obj);
-    if (!result_->fetch(*obj_)) {
     obj_.reset();
+    if (result_->fetch(*obj)) {
+      obj_ = object::object_ptr<Type>(std::make_shared<object::object_proxy<Type>>(result_->resolver_, std::move(obj)));
     }
 
     return *this;
@@ -69,10 +72,11 @@ public:
   self operator++(int) {
     const self tmp(result_, obj_);
 
-    obj_.reset(result_->create());
+    auto obj = result_->create();
-    result_->bind(*obj_);
+    result_->bind(*obj);
-    if (!result_->fetch(*obj_)) {
     obj_.reset();
+    if (result_->fetch(*obj)) {
+      obj_ = object::object_ptr<Type>(std::make_shared<object::object_proxy<Type>>(result_->resolver_, std::move(obj)));
     }
 
     return tmp;
@@ -82,50 +86,37 @@ public:
     return obj_.get();
   }
 
-  reference operator*() {
+  object::object_ptr<Type> operator*() {
-    return *obj_;
+    return obj_;
   }
 
-  pointer get() {
+  object::object_ptr<Type> optr() {
-    return obj_.get();
+    return obj_;
-  }
-
-  pointer release() {
-    return obj_.release();
   }
 
 private:
-  std::unique_ptr<Type> obj_;
+  object::object_ptr<Type> obj_;
   query_result<Type> *result_{nullptr};
 };
 
 namespace detail {
-
 template < typename Type >
-Type* create_prototype(const std::vector<object::attribute> &/*prototype*/) {
+std::shared_ptr<Type> create_prototype(const std::vector<object::attribute> &/*prototype*/) {
-  return new Type{};
+  return std::make_shared<Type>();
 }
 
-template <>
+record create_prototype(const std::vector<object::attribute> &prototype);
-record* create_prototype<record>(const std::vector<object::attribute> &prototype);
-
 }
 
 template<typename Type>
 class query_result final {
 public:
   using iterator = query_result_iterator<Type>;
-  using creator_func = std::function<Type*()>;
+  using creator_func = std::function<std::shared_ptr<Type>()>;
 
-public:
+  query_result(std::unique_ptr<query_result_impl> &&impl, const std::shared_ptr<object::object_resolver<Type>> &resolver, creator_func&& creator)
-  // explicit query_result(std::unique_ptr<query_result_impl> &&impl)
-  // : impl_(std::move(impl))
-  // , creator_([this] {
-  //   return detail::create_prototype<Type>(impl_->prototype());
-  // }) {}
-
-  query_result(std::unique_ptr<query_result_impl> &&impl, creator_func&& creator)
   : impl_(std::move(impl))
+  , resolver_(resolver)
   , creator_(std::move(creator)) {}
 
   iterator begin() { return std::move(++iterator(this)); }
@@ -134,17 +125,18 @@ public:
 private:
   friend class query_result_iterator<Type>;
 
-  Type* create();
+  std::shared_ptr<Type> create();
   void bind(const Type& obj);
   bool fetch(Type& obj);
 
 protected:
   std::unique_ptr<query_result_impl> impl_;
+  std::shared_ptr<object::object_resolver<Type>> resolver_;
   creator_func creator_;
 };
 
 template<typename Type>
-Type *query_result<Type>::create() {
+std::shared_ptr<Type> query_result<Type>::create() {
   return creator_();
 }
 
@@ -157,6 +149,6 @@ template<typename Type>
 bool query_result<Type>::fetch(Type &obj) {
   return impl_->fetch(obj);
 }
-
+}
-} // namespace matador::sql
+// namespace matador::sql
 #endif //QUERY_QUERY_RESULT_HPP

include/matador/sql/record.hpp

@@ -28,6 +28,9 @@ public:
   record& operator=(record&&) noexcept = default;
   ~record() = default;
 
+  bool operator==(const record& rhs) const;
+  bool operator!=(const record& rhs) const;
+
   template<class Operator>
   void process(Operator &op) {
     for(auto &f : fields_) {

include/matador/sql/statement.hpp

@@ -2,20 +2,20 @@
 #define QUERY_STATEMENT_HPP
 
 #include "matador/sql/abstract_sql_logger.hpp"
+#include "matador/sql/error_code.hpp"
 #include "matador/sql/query_result.hpp"
-
 #include "matador/sql/interface/statement_proxy.hpp"
 
+#include "matador/object/basic_repository.hpp"
+
 #include "matador/utils/error.hpp"
 #include "matador/utils/result.hpp"
 
+#include <iostream>
 #include <memory>
 
+
 namespace matador::sql {
-namespace detail {
-template<class Type>
-class identifier_binder;
-}
 
 class statement_impl;
 class statement_proxy;
@@ -104,7 +104,10 @@ public:
    * @return The query result set
    */
   template<class Type>
-  utils::result<std::unique_ptr<Type>, utils::error> fetch_one();
+  utils::result<object::object_ptr<Type>, utils::error> fetch_one();
+
+  template<class Type>
+  utils::result<std::shared_ptr<Type>, utils::error> fetch_one_raw();
   /**
    * Fetches the first result of a prepared statement.
    * The type is a record representing an unknown variable type.
@@ -140,10 +143,6 @@ public:
 
   [[nodiscard]] utils::result<std::unique_ptr<query_result_impl>, utils::error> fetch_internal() const;
 
-private:
-  template<class Type>
-  friend class detail::identifier_binder;
-
 private:
   std::shared_ptr<statement_proxy> statement_proxy_;
   std::unique_ptr<utils::attribute_writer> bindings_;
@@ -165,31 +164,51 @@ statement &statement::bind(const Type &obj) {
 template<class Type>
 utils::result<query_result<Type>, utils::error> statement::fetch() {
   std::cout << statement_proxy_->sql() << std::endl;
-  return statement_proxy_->fetch(*bindings_).and_then([](std::unique_ptr<query_result_impl> &&value) {
+  return statement_proxy_->fetch(*bindings_).and_then([this](std::unique_ptr<query_result_impl> &&value) {
+    auto resolver = statement_proxy_->statement_->query_.resolver_factory->resolver<Type>();
     const auto prototype = value->prototype();
-    return utils::ok(query_result<Type>(std::forward<decltype(value)>(value), [prototype] {
+    return utils::ok(query_result<Type>(std::forward<decltype(value)>(value), resolver, [prototype] {
       return detail::create_prototype<Type>(prototype);
     }));
   });
 }
 
 template<class Type>
-utils::result<std::unique_ptr<Type>, utils::error> statement::fetch_one() {
+utils::result<object::object_ptr<Type>, utils::error> statement::fetch_one() {
   std::cout << statement_proxy_->sql() << std::endl;
   auto result = statement_proxy_->fetch(*bindings_);
   if (!result.is_ok()) {
     return utils::failure(result.err());
   }
+  auto resolver = statement_proxy_->statement_->query_.resolver_factory->resolver<Type>();
   const auto prototype = result.value()->prototype();
-  auto records = query_result<Type>(result.release(), [prototype] {
+  auto records = query_result<Type>(result.release(), resolver, [prototype] {
     return detail::create_prototype<Type>(prototype);
   });
   auto first = records.begin();
   if (first == records.end()) {
-    return utils::ok(std::unique_ptr<Type>{nullptr});
+    return utils::failure(utils::error{
+      error_code::FETCH_FAILED,
+      "Failed to find entity."
+    });
   }
 
-  return utils::ok(std::unique_ptr<Type>{first.release()});
+  return utils::ok(first.optr());
+}
+
+template<class Type>
+utils::result<std::shared_ptr<Type>, utils::error> statement::fetch_one_raw() {
+  auto result = statement_proxy_->fetch(*bindings_);
+  if (!result.is_ok()) {
+    return utils::failure(result.err());
+  }
+
+  auto obj = std::make_shared<Type>();
+  (*result)->bind(*obj);
+  if (!(*result)->fetch(*obj)) {
+    return utils::ok(std::shared_ptr<Type>{});
+  }
+  return utils::ok(obj);
 }
 }
 

include/matador/sql/statement_cache.hpp

@@ -77,7 +77,7 @@ private:
   std::mutex mutex_;
 
   connection_pool &pool_;
-  const sql::dialect &dialect_;
+  const dialect &dialect_;
 
   utils::message_bus &bus_;
 };

include/matador/utils/identifier.hpp

@@ -11,9 +11,7 @@
 #include <typeindex>
 
 namespace matador::utils {
-
+class identifier_serializer {
-class identifier_serializer
-{
 public:
   virtual ~identifier_serializer() = default;
 
@@ -58,21 +56,17 @@ struct identifier_type_traits<const char*, void> {
 };
 
 namespace detail {
-
 template<typename Type>
 size_t hash(const Type &value) {
   return std::hash<Type>()(value);
 }
 
 size_t hash(const char *value);
-
 }
 
-class identifier
+class identifier {
-{
 private:
-  struct base
+  struct base {
-  {
     base(const std::type_index &ti, basic_type type);
     base(const base &x) = delete;
     base &operator=(const base &x) = delete;
@@ -93,14 +87,14 @@ private:
   };
 
   template<class IdType>
-  struct pk final : base
+  struct pk final : base {
-  {
     using self = pk;
 
     explicit pk(const IdType &id)
     : base(std::type_index(typeid(IdType)), data_type_traits<IdType>::type(1))
       , id_(id)
-    , size_(sizeof(IdType)) {}
+      , size_(sizeof(IdType)) {
+    }
 
     [[nodiscard]] base *copy() const override {
       return new self(id_);
@@ -134,8 +128,7 @@ private:
     size_t size_{};
   };
 
-  struct null_pk final : base
+  struct null_pk final : base {
-  {
     null_pk();
     [[nodiscard]] base *copy() const override;
     [[nodiscard]] bool equal_to(const base &x) const override;
@@ -149,25 +142,28 @@ private:
 
 public:
   identifier();
+
   template<typename Type>
   explicit identifier(const Type &id)
-    : id_(std::make_shared<pk<Type>>(id)) {}
+  : id_(std::make_shared<pk<Type> >(id)) {
+  }
+
   explicit identifier(const char *id)
-    : id_(std::make_shared<pk<const char*>>(id)) {}
+  : id_(std::make_shared<pk<const char *> >(id)) {
+  }
+
   identifier(const identifier &x);
   identifier &operator=(const identifier &x);
   identifier(identifier &&x) noexcept;
   identifier &operator=(identifier &&x) noexcept;
 
   template<typename Type>
-  identifier& operator=(const Type &value)
+  identifier &operator=(const Type &value) {
-  {
     id_ = std::make_shared<pk<Type> >(value);
     return *this;
   }
 
-  identifier& operator=(const char *value)
+  identifier &operator=(const char *value) {
-  {
     id_ = std::make_shared<pk<const char *> >(value);
     return *this;
   }
@@ -217,10 +213,10 @@ private:
 static identifier null_identifier{};
 
 /// @cond MATADOR_DEV
-struct id_pk_hash
+struct id_pk_hash {
-{
   size_t operator()(const identifier &id) const;
 };
+
 /// @endcond
 }
 

include/matador/utils/identifier_to_value_converter.hpp

@@ -0,0 +1,29 @@
+#ifndef MATADOR_IDENTIFIER_TO_VALUE_CONVERTER_HPP
+#define MATADOR_IDENTIFIER_TO_VALUE_CONVERTER_HPP
+
+#include "matador/utils/identifier.hpp"
+#include "matador/utils/value.hpp"
+
+namespace matador::utils {
+class identifier_to_value_converter final : public identifier_serializer {
+public:
+  [[nodiscard]] value convert(const identifier &id);
+
+  void serialize(int8_t &, const field_attributes &) override;
+  void serialize(int16_t &, const field_attributes &) override;
+  void serialize(int32_t &, const field_attributes &) override;
+  void serialize(int64_t &, const field_attributes &) override;
+  void serialize(uint8_t &, const field_attributes &) override;
+  void serialize(uint16_t &, const field_attributes &) override;
+  void serialize(uint32_t &, const field_attributes &) override;
+  void serialize(uint64_t &, const field_attributes &) override;
+  void serialize(const char *, const field_attributes &) override;
+  void serialize(std::string &, const field_attributes &) override;
+  void serialize(null_type_t &, const field_attributes &) override;
+
+private:
+  value value_;
+};
+}
+
+#endif //MATADOR_IDENTIFIER_TO_VALUE_CONVERTER_HPP

include/matador/utils/value.hpp

@@ -44,6 +44,9 @@ public:
   value(value &&x) noexcept;
   value& operator=(value &&x) noexcept;
 
+  bool operator==(const value& rhs) const;
+  bool operator!=(const value& rhs) const;
+
   template<class Type>
   std::optional<Type> as() const {
     if (std::holds_alternative<Type>(value_)) {

source/core/CMakeLists.txt

@@ -15,14 +15,19 @@ add_library(matador-core STATIC
   ../../include/matador/net/socket_interrupter.hpp
   ../../include/matador/object/attribute.hpp
   ../../include/matador/object/basic_object_info.hpp
+  ../../include/matador/object/basic_repository.hpp
   ../../include/matador/object/error_code.hpp
   ../../include/matador/object/foreign_node_completer.hpp
+  ../../include/matador/object/internal/observer_list_copy_creator.hpp
+  ../../include/matador/object/internal/observer_list_creator.hpp
   ../../include/matador/object/many_to_many_relation.hpp
   ../../include/matador/object/object.hpp
   ../../include/matador/object/object_generator.hpp
   ../../include/matador/object/object_info.hpp
   ../../include/matador/object/object_proxy.hpp
   ../../include/matador/object/object_ptr.hpp
+  ../../include/matador/object/object_resolver.hpp
+  ../../include/matador/object/object_resolver_factory.hpp
   ../../include/matador/object/observer.hpp
   ../../include/matador/object/primary_key_resolver.hpp
   ../../include/matador/object/relation_completer.hpp
@@ -31,7 +36,6 @@ add_library(matador-core STATIC
   ../../include/matador/object/repository_node.hpp
   ../../include/matador/object/repository_node_iterator.hpp
   ../../include/matador/object/restriction.hpp
-  ../../include/matador/sql/statement_cache.hpp
   ../../include/matador/utils/access.hpp
   ../../include/matador/utils/attribute_reader.hpp
   ../../include/matador/utils/attribute_writer.hpp
@@ -53,6 +57,7 @@ add_library(matador-core STATIC
   ../../include/matador/utils/file.hpp
   ../../include/matador/utils/foreign_attributes.hpp
   ../../include/matador/utils/identifier.hpp
+  ../../include/matador/utils/identifier_to_value_converter.hpp
   ../../include/matador/utils/leader_follower_thread_pool.hpp
   ../../include/matador/utils/library.hpp
   ../../include/matador/utils/macro_map.hpp
@@ -78,6 +83,7 @@ add_library(matador-core STATIC
   logger/rotating_file_sink.cpp
   object/attribute.cpp
   object/basic_object_info.cpp
+  object/basic_repository.cpp
   object/error_code.cpp
   object/foreign_node_completer.cpp
   object/object.cpp
@@ -95,6 +101,7 @@ add_library(matador-core STATIC
   utils/file.cpp
   utils/foreign_attributes.cpp
   utils/identifier.cpp
+  utils/identifier_to_value_converter.cpp
   utils/leader_follower_thread_pool.cpp
   utils/library.cpp
   utils/message_bus.cpp
@@ -106,10 +113,6 @@ add_library(matador-core STATIC
   utils/uuid.cpp
   utils/value.cpp
   utils/version.cpp
-  ../../include/matador/object/internal/observer_list_creator.hpp
-  ../../include/matador/object/internal/observer_list_copy_creator.hpp
-  ../../include/matador/object/basic_repository.hpp
-  object/basic_repository.cpp
 )
 
 target_link_libraries(matador-core ${CMAKE_DL_LIBS})

source/core/utils/identifier_to_value_converter.cpp

@@ -0,0 +1,53 @@
+#include "matador/utils/identifier_to_value_converter.hpp"
+
+namespace matador::utils {
+value identifier_to_value_converter::convert(const identifier &id) {
+  id.serialize(*this);
+
+  return value_;
+}
+
+void identifier_to_value_converter::serialize(int8_t &x, const field_attributes &) {
+  value_ = x;
+}
+
+void identifier_to_value_converter::serialize(int16_t &x, const field_attributes &) {
+  value_ = x;
+}
+
+void identifier_to_value_converter::serialize(int32_t &x, const field_attributes &) {
+  value_ = x;
+}
+
+void identifier_to_value_converter::serialize(int64_t &x, const field_attributes &) {
+  value_ = x;
+}
+
+void identifier_to_value_converter::serialize(uint8_t &x, const field_attributes &) {
+  value_ = x;
+}
+
+void identifier_to_value_converter::serialize(uint16_t &x, const field_attributes &) {
+  value_ = x;
+}
+
+void identifier_to_value_converter::serialize(uint32_t &x, const field_attributes &) {
+  value_ = x;
+}
+
+void identifier_to_value_converter::serialize(uint64_t &x, const field_attributes &) {
+  value_ = x;
+}
+
+void identifier_to_value_converter::serialize(const char *x, const field_attributes &) {
+  value_ = x;
+}
+
+void identifier_to_value_converter::serialize(std::string &x, const field_attributes &) {
+  value_ = x;
+}
+
+void identifier_to_value_converter::serialize(null_type_t &/*x*/, const field_attributes &) {
+  value_.type(basic_type::Null);
+}
+}

source/core/utils/value.cpp

@@ -39,6 +39,14 @@ value &value::operator=(value &&x) noexcept {
   return *this;
 }
 
+bool value::operator==(const value &rhs) const {
+  return type_ == rhs.type_ && value_ == rhs.value_;
+}
+
+bool value::operator!=(const value &rhs) const {
+  return !operator==(rhs);
+}
+
 std::string value::str() const {
   return as<std::string>().value_or("");
 }

source/orm/CMakeLists.txt

@@ -1,8 +1,8 @@
 add_library(matador-orm STATIC
   ../../include/matador/orm/error_code.hpp
   ../../include/matador/orm/session.hpp
-  ../../include/matador/orm/session_query_builder.hpp
   ../../include/matador/query/attribute_string_writer.hpp
+  ../../include/matador/query/basic_schema.hpp
   ../../include/matador/query/builder.hpp
   ../../include/matador/query/criteria.hpp
   ../../include/matador/query/criteria/abstract_column_criteria.hpp
@@ -50,10 +50,13 @@ add_library(matador-orm STATIC
   ../../include/matador/query/join_data.hpp
   ../../include/matador/query/key_value_generator.hpp
   ../../include/matador/query/meta_table_macro.hpp
+  ../../include/matador/query/meta_table_macro.hpp
   ../../include/matador/query/query.hpp
+  ../../include/matador/query/query_builder.hpp
   ../../include/matador/query/query_compiler.hpp
   ../../include/matador/query/query_data.hpp
   ../../include/matador/query/query_intermediates.hpp
+  ../../include/matador/query/query_object_resolver.hpp
   ../../include/matador/query/query_part.hpp
   ../../include/matador/query/query_utils.hpp
   ../../include/matador/query/schema.hpp
@@ -76,19 +79,25 @@ add_library(matador-orm STATIC
   ../../include/matador/sql/interface/query_result_reader.hpp
   ../../include/matador/sql/interface/statement_impl.hpp
   ../../include/matador/sql/interface/statement_proxy.hpp
+  ../../include/matador/sql/internal/identifier_reader.hpp
+  ../../include/matador/sql/internal/identifier_statement_binder.hpp
   ../../include/matador/sql/internal/object_result_binder.hpp
   ../../include/matador/sql/internal/query_result_impl.hpp
   ../../include/matador/sql/internal/query_result_pk_resolver.hpp
+  ../../include/matador/sql/internal/resolver_producer.hpp
+  ../../include/matador/sql/internal/statement_object_resolver.hpp
+  ../../include/matador/sql/producer_resolver_factory.hpp
   ../../include/matador/sql/query_context.hpp
+  ../../include/matador/sql/query_record_result.hpp
   ../../include/matador/sql/query_result.hpp
   ../../include/matador/sql/record.hpp
   ../../include/matador/sql/sql_functions.hpp
   ../../include/matador/sql/statement.hpp
+  ../../include/matador/sql/statement_cache.hpp
   orm/error_code.cpp
-  orm/query_builder_exception.cpp
   orm/session.cpp
-  orm/session_query_builder.cpp
   query/attribute_string_writer.cpp
+  query/basic_schema.cpp
   query/builder.cpp
   query/criteria/abstract_column_criteria.cpp
   query/criteria/between_criteria.cpp
@@ -133,7 +142,10 @@ add_library(matador-orm STATIC
   query/internal/query_result_impl.cpp
   query/key_value_generator.cpp
   query/query.cpp
+  query/query_builder.cpp
+  query/query_builder_exception.cpp
   query/query_compiler.cpp
+  query/query_object_resolver.cpp
   query/query_part.cpp
   query/query_utils.cpp
   query/schema.cpp
@@ -153,14 +165,17 @@ add_library(matador-orm STATIC
   sql/interface/query_result_reader.cpp
   sql/interface/statement_impl.cpp
   sql/interface/statement_proxy.cpp
+  sql/internal/identifier_reader.cpp
+  sql/internal/identifier_statement_binder.cpp
   sql/internal/object_result_binder.cpp
   sql/internal/query_result_pk_resolver.cpp
+  sql/internal/resolver_producer.cpp
   sql/object_parameter_binder.cpp
+  sql/producer_resolver_factory.cpp
   sql/query_result.cpp
   sql/record.cpp
   sql/statement.cpp
   sql/statement_cache.cpp
-  ../../include/matador/query/meta_table_macro.hpp
 )
 
 target_include_directories(matador-orm

source/orm/orm/session.cpp

@@ -2,6 +2,7 @@
 
 #include "matador/sql/backend_provider.hpp"
 #include "matador/sql/dialect.hpp"
+#include "matador/sql/query_record_result.hpp"
 
 #include "matador/query/query.hpp"
 
@@ -13,9 +14,11 @@ utils::error make_error(const error_code ec, const std::string &msg) {
 }
 
 session::session(session_context&& ctx, const query::schema &scm)
-: cache_(ctx.bus, ctx.pool, ctx.cache_size)
+: pool_(ctx.dns, ctx.connection_count, [ctx](const sql::connection_info& info) { return sql::connection(info, ctx.resolver_factory); })
-, dialect_(sql::backend_provider::instance().connection_dialect(ctx.pool.info().type))
+, cache_(ctx.bus, pool_, ctx.cache_size)
-, schema_(scm) {
+, dialect_(sql::backend_provider::instance().connection_dialect(pool_.info().type))
+, schema_(scm)
+, resolver_factory_(ctx.resolver_factory) {
 }
 
 utils::result<void, utils::error> session::drop_table(const std::string &table_name) const {
@@ -55,9 +58,7 @@ utils::result<sql::query_result<sql::record>, utils::error> session::fetch_all(c
     return utils::failure(res.err());
   }
   const auto prototype = res.value()->prototype();
-    return utils::ok(sql::query_result<sql::record>{std::move(*res), [prototype] {
+  return utils::ok(sql::query_result<sql::record>{std::move(*res), prototype});
-        return sql::detail::create_prototype<sql::record>(prototype);
-      }});
 }
 
 utils::result<size_t, utils::error> session::execute(const std::string &sql) const {
@@ -84,6 +85,14 @@ const class sql::dialect &session::dialect() const {
   return dialect_;
 }
 
+std::shared_ptr<sql::producer_resolver_factory> session::resolver_factory() const {
+  return resolver_factory_;
+}
+
+const query::basic_schema & session::schema() const {
+  return schema_;
+}
+
 utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> session::fetch(const sql::query_context& ctx) const {
     if (const auto result = cache_.acquire(ctx); !result) {
         return utils::failure(result.err());
@@ -112,7 +121,7 @@ std::string session::str(const sql::query_context& ctx) const {
   return ctx.sql;
 }
 
-query::fetchable_query session::build_select_query(entity_query_data &&data) {
+query::fetchable_query session::build_select_query(query::entity_query_data &&data) {
   return query::query::select(data.columns)
       .from(*data.root_table)
       .join_left(data.joins)

source/orm/orm/session_query_builder.cpp

@@ -1,83 +0,0 @@
-#include "matador/orm/session_query_builder.hpp"
-
-#include <iostream>
-
-namespace matador::orm {
-criteria_transformer::criteria_transformer(const query::schema& repo, const std::unordered_map<std::string, query::table>& tables_by_name)
-: repo_(repo)
-, tables_by_name_(tables_by_name) {}
-
-void criteria_transformer::visit( const query::between_criteria& node ) {
-  update_criteria_column(node);
-}
-
-void criteria_transformer::visit( const query::binary_criteria& node ) {
-  update_criteria_column(node);
-}
-
-void criteria_transformer::visit( const query::binary_column_criteria& /*node*/ ) {}
-
-void criteria_transformer::visit( const query::collection_criteria& node ) {
-  update_criteria_column(node);
-}
-
-void criteria_transformer::visit( const query::collection_query_criteria& node ) {
-  update_criteria_column(node);
-}
-
-void criteria_transformer::visit( const query::like_criteria& node ) {
-  update_criteria_column(node);
-}
-
-void criteria_transformer::visit( const query::logical_criteria& node ) {
-  node.left_clause()->accept(*this);
-  node.right_clause()->accept(*this);
-}
-
-void criteria_transformer::visit( const query::not_criteria& node ) {
-  node.clause()->accept(*this);
-}
-
-void criteria_transformer::update_criteria_column(const query::abstract_column_criteria& node) const {
-  if (node.col().table() == nullptr) {
-    return;
-  }
-  const auto it = tables_by_name_.find(node.col().table()->name());
-  if (it == tables_by_name_.end()) {
-    return;
-  }
-
-  const_cast<query::table_column&>(node.col()).table(&it->second);
-}
-
-void session_query_builder::on_revision(const char *id, uint64_t &/*rev*/) {
-  push(id);
-}
-
-void session_query_builder::push(const std::string &column_name) {
-  const auto it = processed_tables_.find(table_info_stack_.top().info.name());
-  if (it == processed_tables_.end()) {
-    throw query_builder_exception{query_build_error::UnexpectedError};
-  }
-  entity_query_data_.columns.emplace_back(&it->second, column_name, build_alias('c', ++column_index));
-}
-
-std::string session_query_builder::build_alias(const char prefix, const unsigned int count) {
-  char str[4];
-  snprintf(str, 4, "%c%02d", prefix, count);
-
-  return str;
-}
-
-[[nodiscard]] bool session_query_builder::is_root_entity() const {
-  return table_info_stack_.size() == 1;
-}
-
-void session_query_builder::append_join(const query::table_column &left, const query::table_column &right) {
-  using namespace matador::query;
-  entity_query_data_.joins.push_back({
-    right.table(),
-    std::make_unique<binary_column_criteria>(left, binary_operator::EQUALS, right)
-  });
-}
-}

source/orm/query/basic_schema.cpp

@@ -0,0 +1,92 @@
+#include "matador/query/basic_schema.hpp"
+
+#include "matador/sql/executor.hpp"
+
+namespace matador::query {
+schema_node::schema_node(class table tab, const object::repository_node& node)
+: table_(std::move(tab))
+, node_(std::move(node)) {
+}
+
+const std::string & schema_node::name() const {
+  return table_.name();
+}
+
+const table &schema_node::table() const {
+  return table_;
+}
+
+const object::repository_node& schema_node::node() const {
+  return node_;
+}
+
+basic_schema::basic_schema()
+: basic_schema("") {}
+
+basic_schema::basic_schema(const std::string &name)
+: repo_(name) {
+}
+
+basic_schema::iterator basic_schema::begin() {
+  return schema_nodes_.begin();
+}
+
+basic_schema::iterator basic_schema::end() {
+  return schema_nodes_.end();
+}
+
+basic_schema::const_iterator basic_schema::begin() const {
+  return schema_nodes_.begin();
+}
+
+basic_schema::const_iterator basic_schema::end() const {
+  return schema_nodes_.end();
+}
+
+size_t basic_schema::size() const {
+  return schema_nodes_.size();
+}
+
+bool basic_schema::empty() const {
+  return schema_nodes_.empty();
+}
+
+basic_schema::iterator basic_schema::find(const std::type_index &ti) {
+  return schema_nodes_.find(ti);
+}
+
+basic_schema::const_iterator basic_schema::find(const std::type_index &ti) const {
+  return schema_nodes_.find(ti);
+}
+
+basic_schema::iterator basic_schema::find(const std::string &name) {
+  const auto result = repo_.basic_info(name);
+  if (!result) {
+    return schema_nodes_.end();
+  }
+
+  return schema_nodes_.find(result->get().type_index());
+}
+
+basic_schema::const_iterator basic_schema::find(const std::string &name) const {
+  const auto result = repo_.basic_info(name);
+  if (!result) {
+    return schema_nodes_.end();
+  }
+
+  return schema_nodes_.find(result->get().type_index());
+}
+
+bool basic_schema::contains(const std::type_index &index) const {
+  return schema_nodes_.count(index) == 1;
+}
+
+void basic_schema::initialize_executor(sql::executor &exec) const {
+  auto factory = std::make_shared<sql::producer_resolver_factory>();
+  for (const auto &[key, producer] : resolver_producers_) {
+    auto resolver = producer->produce(exec);
+    exec.resolver_factory()->register_resolver(std::move(resolver));
+  }
+}
+
+}

source/orm/query/criteria/criteria_operators.cpp

@@ -5,7 +5,22 @@
 #include "matador/query/criteria/logical_criteria.hpp"
 #include "matador/query/criteria/not_criteria.hpp"
 
+#include "matador/utils/identifier.hpp"
+#include "matador/utils/identifier_to_value_converter.hpp"
+
 namespace matador::query {
+criteria_ptr operator==(const table_column &col, const utils::identifier &id) {
+  utils::identifier_to_value_converter conv;
+
+  return std::make_unique<binary_criteria>(col, binary_operator::EQUALS, conv.convert(id));
+}
+
+criteria_ptr operator!=(const table_column &col, const utils::identifier &id) {
+  utils::identifier_to_value_converter conv;
+
+  return std::make_unique<binary_criteria>(col, binary_operator::NOT_EQUALS, conv.convert(id));
+}
+
 criteria_ptr operator==(const table_column &col, utils::placeholder p) {
   return std::make_unique<binary_criteria>(col, binary_operator::EQUALS, p);
 }

source/orm/query/generator.cpp

@@ -1,7 +1,7 @@
 #include "matador/query/generator.hpp"
 
 namespace matador::query::generator {
-column_generator::column_generator(const schema& repo, const table* tab, const column_generator_options options)
+column_generator::column_generator(const basic_schema& repo, const table* tab, const column_generator_options options)
 : repo_(std::cref(repo))
 , options_(options) {
   table_stack_.push(tab);

source/orm/query/intermediates/fetchable_query.cpp

@@ -3,6 +3,7 @@
 #include "matador/sql/executor.hpp"
 #include "matador/sql/field.hpp"
 #include "matador/sql/statement.hpp"
+#include "matador/sql/query_record_result.hpp"
 
 namespace matador::query {
 
@@ -29,29 +30,27 @@ utils::result<sql::query_result<sql::record>, utils::error> fetchable_query::fet
   return exec.fetch(ctx)
     .and_then([](auto &&res) {
       const auto prototype = res->prototype();
-      return utils::ok(sql::query_result<sql::record>(std::forward<decltype(res)>(res), [prototype] {
+      return utils::ok(sql::query_result<sql::record>(std::forward<decltype(res)>(res), prototype));
-        return detail::create_prototype(prototype);
-      }));
     });
 }
 
 utils::result<std::optional<sql::record>, utils::error> fetchable_query::fetch_one(const sql::executor &exec) const {
   query_compiler compiler;
-  auto result = exec.fetch(compiler.compile(*context_, exec.dialect(), std::nullopt));
+  auto ctx = compiler.compile(*context_, exec.dialect(), std::nullopt);
+  ctx.resolver_factory = exec.resolver_factory();
+  auto result = exec.fetch(ctx);
   if (!result.is_ok()) {
     return utils::failure(result.err());
   }
 
   const auto prototype = result.value()->prototype();
-  sql::query_result<sql::record> records(std::move(*result), [prototype] {
+  sql::query_result<sql::record> records(std::move(*result), prototype);
-    return detail::create_prototype(prototype);
-  });
   auto first = records.begin();
   if (first == records.end()) {
     return utils::ok(std::optional<sql::record>{std::nullopt});
   }
 
-  return utils::ok(std::optional{*first.get()});
+  return utils::ok(std::optional{first.release()});
 }
 
 std::string fetchable_query::str(const sql::executor &exec) const {
@@ -64,11 +63,15 @@ sql::query_context fetchable_query::compile(const sql::dialect &d) const {
 }
 
 utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> fetchable_query::fetch(const sql::executor &exec) const {
-  return exec.fetch(compile(exec.dialect()));
+  auto ctx = compile(exec.dialect());
+  ctx.resolver_factory = exec.resolver_factory();
+  return exec.fetch(ctx);
 }
 
 utils::result<sql::statement, utils::error> fetchable_query::prepare(sql::executor &exec) const {
-  return exec.prepare(compile(exec.dialect()));
+  auto ctx = compile(exec.dialect());
+  ctx.resolver_factory = exec.resolver_factory();
+  return exec.prepare(ctx);
 }
 
 }

source/orm/query/internal/query_result_impl.cpp

@@ -8,20 +8,14 @@ detail::pk_reader::pk_reader(query_result_reader &reader)
 }
 
 query_result_impl::query_result_impl(std::unique_ptr<query_result_reader> &&reader,
-                                     std::vector<object::attribute> &&prototype,
+                                     std::vector<object::attribute> prototype,
+                                     const std::shared_ptr<object::object_resolver_factory>& resolver_factory,
                                      const size_t column_index)
 : column_index_(column_index)
 , prototype_(std::move(prototype))
 , reader_(std::move(reader))
-  , pk_reader_(*reader_) {
+, resolver_factory_(resolver_factory)
-}
+, id_reader_(*reader_)
-
-query_result_impl::query_result_impl(std::unique_ptr<query_result_reader> &&reader,
-                                     const std::vector<object::attribute> &prototype,
-                                     const size_t column_index)
-: column_index_(column_index)
-  , prototype_(prototype)
-  , reader_(std::move(reader))
 , pk_reader_(*reader_) {
 }
 

source/orm/query/query_builder.cpp

@@ -0,0 +1,81 @@
+#include "matador/query/query_builder.hpp"
+
+namespace matador::query {
+criteria_transformer::criteria_transformer(const basic_schema& repo, const std::unordered_map<std::string, table>& tables_by_name)
+: repo_(repo)
+, tables_by_name_(tables_by_name) {}
+
+void criteria_transformer::visit( const between_criteria& node ) {
+  update_criteria_column(node);
+}
+
+void criteria_transformer::visit( const binary_criteria& node ) {
+  update_criteria_column(node);
+}
+
+void criteria_transformer::visit( const binary_column_criteria& /*node*/ ) {}
+
+void criteria_transformer::visit( const collection_criteria& node ) {
+  update_criteria_column(node);
+}
+
+void criteria_transformer::visit( const collection_query_criteria& node ) {
+  update_criteria_column(node);
+}
+
+void criteria_transformer::visit( const like_criteria& node ) {
+  update_criteria_column(node);
+}
+
+void criteria_transformer::visit( const logical_criteria& node ) {
+  node.left_clause()->accept(*this);
+  node.right_clause()->accept(*this);
+}
+
+void criteria_transformer::visit( const not_criteria& node ) {
+  node.clause()->accept(*this);
+}
+
+void criteria_transformer::update_criteria_column(const abstract_column_criteria& node) const {
+  if (node.col().table() == nullptr) {
+    return;
+  }
+  const auto it = tables_by_name_.find(node.col().table()->name());
+  if (it == tables_by_name_.end()) {
+    return;
+  }
+
+  const_cast<table_column&>(node.col()).table(&it->second);
+}
+
+void query_builder::on_revision(const char *id, uint64_t &/*rev*/) {
+  push(id);
+}
+
+void query_builder::push(const std::string &column_name) {
+  const auto it = processed_tables_.find(table_info_stack_.top().info.name());
+  if (it == processed_tables_.end()) {
+    throw query_builder_exception{query_build_error::UnexpectedError};
+  }
+  entity_query_data_.columns.emplace_back(&it->second, column_name, build_alias('c', ++column_index));
+}
+
+std::string query_builder::build_alias(const char prefix, const unsigned int count) {
+  char str[4];
+  snprintf(str, 4, "%c%02d", prefix, count);
+
+  return str;
+}
+
+[[nodiscard]] bool query_builder::is_root_entity() const {
+  return table_info_stack_.size() == 1;
+}
+
+void query_builder::append_join(const table_column &left, const table_column &right) {
+  using namespace matador::query;
+  entity_query_data_.joins.push_back({
+    right.table(),
+    std::make_unique<binary_column_criteria>(left, binary_operator::EQUALS, right)
+  });
+}
+}

source/orm/query/query_builder_exception.cpp

@@ -1,6 +1,6 @@
-#include "matador/orm/query_builder_exception.hpp"
+#include "matador/query/query_builder_exception.hpp"
 
-namespace matador::orm {
+namespace matador::query {
 
 query_builder_exception::query_builder_exception(const query_build_error error, utils::error&& err)
 : error_type_(error)

source/orm/query/query_object_resolver.cpp

@@ -0,0 +1,16 @@
+#include "matador/query/query_object_resolver.hpp"
+
+#include "matador/query/criteria.hpp"
+#include "matador/query/query.hpp"
+
+namespace matador::query {
+utils::result<sql::statement, utils::error> prepare_statement(sql::executor &exec, entity_query_data &&data) {
+  return query::query::select(data.columns)
+      .from(*data.root_table)
+      .join_left(data.joins)
+      .where(std::move(data.where_clause))
+      .order_by({data.root_table, data.pk_column_name})
+      .asc()
+      .prepare(exec);
+}
+}

source/orm/query/schema.cpp

@@ -11,26 +11,6 @@
 #include "matador/sql/dialect.hpp"
 
 namespace matador::query {
-schema_node::schema_node(class table tab, const object::repository_node& node)
-: table_(std::move(tab))
-, node_(std::move(node)) {
-}
-
-const std::string & schema_node::name() const {
-  return table_.name();
-}
-
-const table &schema_node::table() const {
-  return table_;
-}
-
-const object::repository_node& schema_node::node() const {
-  return node_;
-}
-
-schema::schema(const std::string &name)
-: repo_(name) {
-}
 
 utils::result<void, utils::error> schema::create(const sql::connection &conn) const {
   // Step 1: Build dependency graph
@@ -64,7 +44,7 @@ utils::result<void, utils::error> schema::create(const sql::connection &conn) co
 
   std::vector<std::string> fk_sql_commands;
 
-  const auto q = query::query::create().schema(repo_.name()).compile(conn);
+  const auto q = query::create().schema(repo_.name()).compile(conn);
   std::cout << q.sql << std::endl;
 
   // create plain tables without constraints
@@ -184,60 +164,6 @@ utils::result<bool, utils::error> schema::table_exists(const std::string &table_
   return conn.exists(repo_.name(), table_name);
 }
 
-schema::iterator schema::begin() {
-  return schema_nodes_.begin();
-}
-
-schema::iterator schema::end() {
-  return schema_nodes_.end();
-}
-
-schema::const_iterator schema::begin() const {
-  return schema_nodes_.begin();
-}
-
-schema::const_iterator schema::end() const {
-  return schema_nodes_.end();
-}
-
-size_t schema::size() const {
-  return schema_nodes_.size();
-}
-
-bool schema::empty() const {
-  return schema_nodes_.empty();
-}
-
-schema::iterator schema::find(const std::type_index &ti) {
-  return schema_nodes_.find(ti);
-}
-
-schema::const_iterator schema::find(const std::type_index &ti) const {
-  return schema_nodes_.find(ti);
-}
-
-schema::iterator schema::find(const std::string &name) {
-  const auto result = repo_.basic_info(name);
-  if (!result) {
-    return schema_nodes_.end();
-  }
-
-  return schema_nodes_.find(result->get().type_index());
-}
-
-schema::const_iterator schema::find(const std::string &name) const {
-  const auto result = repo_.basic_info(name);
-  if (!result) {
-    return schema_nodes_.end();
-  }
-
-  return schema_nodes_.find(result->get().type_index());
-}
-
-bool schema::contains(const std::type_index &index) const {
-  return schema_nodes_.count(index) == 1;
-}
-
 void schema::dump(std::ostream &os) const {
   repo_.dump(os);
 }
@@ -269,11 +195,11 @@ sql::query_context schema::build_drop_constraint_context(const object::repositor
       .compile(conn);
 }
 
-void schema::insert_table(const std::type_index &ti, const object::repository_node &node) {
+schema::iterator schema::insert_table(const std::type_index &ti, const object::repository_node &node) {
   std::vector<table_column> columns;
   for (const auto &attr: node.info().attributes()) {
     columns.emplace_back(nullptr, attr.name(), attr.type(), attr.attributes());
   }
-  std::ignore = schema_nodes_.insert({ti, schema_node{table(node.name(), columns), node}}).first;
+  return schema_nodes_.insert({ti, schema_node{table(node.name(), columns), node}}).first;
 }
 } // namespace matador::query

source/orm/sql/connection.cpp

@@ -3,7 +3,6 @@
 #include "matador/sql/backend_provider.hpp"
 #include "matador/sql/dialect.hpp"
 #include "matador/sql/dialect_token.hpp"
-#include "matador/sql/error_code.hpp"
 #include "matador/sql/interface/connection_impl.hpp"
 
 
@@ -28,16 +27,29 @@ public:
 };
 
 }
-connection::connection(const connection_info& info, const std::shared_ptr<abstract_sql_logger> &sql_logger)
+connection::connection(const connection_info& info, logger_ptr sql_logger)
-: logger_(sql_logger)
+: logger_(std::move(sql_logger)) {
-{
   connection_.reset(backend_provider::instance().create_connection(info.type, info));
 }
 
-connection::connection(const std::string& dns, const std::shared_ptr<abstract_sql_logger> &sql_logger)
+connection::connection(const connection_info &info,
+                       std::shared_ptr<producer_resolver_factory> resolver_factory,
+                       logger_ptr sql_logger)
+: logger_(std::move(sql_logger))
+, resolver_factory_(std::move(resolver_factory)) {
+  connection_.reset(backend_provider::instance().create_connection(info.type, info));
+}
+
+connection::connection(const std::string& dns, const logger_ptr &sql_logger)
 : connection(connection_info::parse(dns), sql_logger)
 {}
 
+connection::connection(const std::string &dns,
+                       std::shared_ptr<producer_resolver_factory> resolver_factory,
+                       const logger_ptr &sql_logger)
+: connection(connection_info::parse(dns), std::move(resolver_factory), sql_logger)
+{}
+
 connection::connection(const connection &x) {
   if (x.connection_) {
     throw std::runtime_error("couldn't copy connection with valid connection impl");
@@ -58,11 +70,13 @@ connection &connection::operator=(const connection &x) {
 connection::connection( connection&& x ) noexcept
 : connection_(std::move(x.connection_))
 , logger_(std::move(x.logger_))
+, resolver_factory_(std::move(x.resolver_factory_))
 {}
 
 connection & connection::operator=(connection &&x) noexcept {
   connection_  = std::move(x.connection_);
   logger_ = std::move(x.logger_);
+  resolver_factory_ = std::move(x.resolver_factory_);
 
   return *this;
 }
@@ -71,7 +85,7 @@ connection::~connection() {
   if (!connection_) {
     return;
   }
-  if (connection_->is_open()) {
+  if (const auto result = connection_->is_open(); *result) {
     connection_->close();
   }
   connection_impl* impl = connection_.release();
@@ -219,6 +233,10 @@ const class dialect &connection::dialect() const
   return connection_->dialect();
 }
 
+std::shared_ptr<class producer_resolver_factory> connection::resolver_factory() const {
+  return resolver_factory_;
+}
+
 utils::result<std::unique_ptr<statement_impl>, utils::error> connection::perform_prepare(const query_context& ctx) const {
   if (ctx.command != sql_command::SQL_CREATE_TABLE && (ctx.prototype.empty() || has_unknown_columns(ctx.prototype))) {
     if (const auto result = describe(ctx.table_name); result.is_ok()) {

source/orm/sql/connection_pool.cpp

@@ -53,21 +53,19 @@ bool connection_ptr::valid() const {
   return connection_ != nullptr;
 }
 
-connection_pool::connection_pool(const std::string& dns, size_t count)
+connection_pool::connection_pool(const std::string& dns, const size_t count)
-: info_(connection_info::parse(dns)) {
+: connection_pool(dns, count, [](const connection_info &info) { return connection{info}; })
+{}
+
+connection_pool::connection_pool(const std::string &dns, size_t count, std::function<connection(const connection_info &)> &&connection_creator)
+: info_(connection_info::parse(dns))
+, connection_creator_(std::move(connection_creator)) {
   connection_repo_.reserve(count);
   while (count) {
-    // connection c(info_);
+    connection_repo_.emplace_back(count, connection_creator_(info_));
-      // auto&& cc = std::move(c);
-      // const auto ic = identifiable_connection{count, std::move(cc)};
-    // connection_repo_.push_back(ic);
-    // connection_repo_.emplace_back(count, std::move(cc));
-    connection_repo_.emplace_back(count, connection{info_});
     auto &conn = connection_repo_.back();
     idle_connections_.emplace(conn.id, &conn);
-    // Todo: handle result
+    if (const auto result = conn.conn.open(); !result) {
-    const auto result = conn.conn.open();
-    if (!result) {
       throw std::runtime_error("Failed to open connection");
     }
     --count;

source/orm/sql/field.cpp

@@ -35,6 +35,17 @@ field &field::operator=(field &&x) noexcept {
   return *this;
 }
 
+bool field::operator==(const field &rhs) const {
+  return name_ == rhs.name_ &&
+    type_ == rhs.type_ &&
+    index_ == rhs.index_ &&
+    value_ == rhs.value_;
+}
+
+bool field::operator!=(const field &rhs) const {
+  return !operator==(rhs);
+}
+
 const std::string &field::name() const {
   return name_;
 }

source/orm/sql/internal/identifier_reader.cpp

@@ -0,0 +1,6 @@
+#include "matador/sql/internal/identifier_reader.hpp"
+
+namespace matador::sql::internal {
+identifier_reader::identifier_reader(query_result_reader &reader)
+: reader_(reader) {}
+}

source/orm/sql/internal/identifier_statement_binder.cpp

@@ -0,0 +1,56 @@
+#include "matador/sql/internal/identifier_statement_binder.hpp"
+
+#include "matador/sql/statement.hpp"
+
+namespace matador::sql {
+identifier_statement_binder::identifier_statement_binder(statement &stmt, const size_t index)
+: stmt_(stmt)
+, index_(index) {}
+
+void identifier_statement_binder::bind(const utils::identifier &id) {
+  id.serialize(*this);
+}
+
+void identifier_statement_binder::serialize(int8_t &value, const utils::field_attributes &) {
+  stmt_.bind(index_, value);
+}
+
+void identifier_statement_binder::serialize(int16_t &value, const utils::field_attributes &) {
+  stmt_.bind(index_, value);
+}
+
+void identifier_statement_binder::serialize(int32_t &value, const utils::field_attributes &) {
+  stmt_.bind(index_, value);
+}
+
+void identifier_statement_binder::serialize(int64_t &value, const utils::field_attributes &) {
+  stmt_.bind(index_, value);
+}
+
+void identifier_statement_binder::serialize(uint8_t &value, const utils::field_attributes &) {
+  stmt_.bind(index_, value);
+}
+
+void identifier_statement_binder::serialize(uint16_t &value, const utils::field_attributes &) {
+  stmt_.bind(index_, value);
+}
+
+void identifier_statement_binder::serialize(uint32_t &value, const utils::field_attributes &) {
+  stmt_.bind(index_, value);
+}
+
+void identifier_statement_binder::serialize(uint64_t &value, const utils::field_attributes &) {
+  stmt_.bind(index_, value);
+}
+
+void identifier_statement_binder::serialize(const char *value, const utils::field_attributes &) {
+  stmt_.bind(index_, value);
+}
+
+void identifier_statement_binder::serialize(std::string &value, const utils::field_attributes &) {
+  stmt_.bind(index_, value);
+}
+
+void identifier_statement_binder::serialize(utils::null_type_t &/*value*/, const utils::field_attributes &) {
+}
+}

source/orm/sql/internal/resolver_producer.cpp

@@ -0,0 +1,10 @@
+#include "matador/sql/internal/resolver_producer.hpp"
+
+namespace matador::sql {
+const std::type_index & resolver_producer::type() const {
+  return type_;
+}
+
+resolver_producer::resolver_producer(const std::type_index &type)
+: type_(type) {}
+}

source/orm/sql/producer_resolver_factory.cpp

@@ -0,0 +1,14 @@
+#include "matador/sql/producer_resolver_factory.hpp"
+
+namespace matador::sql {
+std::shared_ptr<object::abstract_object_resolver> producer_resolver_factory::acquire_resolver(const std::type_index &type) {
+  if (const auto it = resolvers_.find(type); it != resolvers_.end()) {
+    return it->second;
+  }
+  return nullptr;
+}
+
+void producer_resolver_factory::register_resolver(std::shared_ptr<object::abstract_object_resolver> &&resolver) {
+  resolvers_[resolver->type()] = std::move(resolver);
+}
+}

source/orm/sql/query_result.cpp

@@ -5,12 +5,11 @@
 
 namespace matador::sql::detail {
 
-template<>
+record create_prototype(const std::vector<object::attribute> &prototype) {
-record *create_prototype<record>(const std::vector<object::attribute> &prototype) {
+  record rec;
-  auto result = std::make_unique<record>();
   int index{0};
   for (const auto &col: prototype) {
-    result->append({
+    rec.append({
         col.name(),
         col.type(),
         col.attributes().options(),
@@ -18,7 +17,7 @@ record *create_prototype<record>(const std::vector<object::attribute> &prototype
         index++
     });
   }
-  return result.release();
+  return rec;
 }
 
 

source/orm/sql/record.cpp

@@ -70,9 +70,25 @@ record::const_iterator record::find(const std::string &column_name) const {
   return it != fields_by_name_.end() ? fields_.begin() + it->second.second : fields_.end();
 }
 
+bool record::operator==(const record &rhs) const {
+  if (size() != rhs.size()) {
+    return false;
+  }
+  for(size_t i = 0; i < size(); ++i) {
+    if (at(i) != rhs.at(i)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool record::operator!=(const record &rhs) const {
+  return !operator==(rhs);
+}
+
 void record::append(const field &col) {
-  const auto it = fields_by_name_.emplace(col.name(), field_index_pair {col, fields_.size()});
+  const auto [fst, snd] = fields_by_name_.emplace(col.name(), field_index_pair {col, fields_.size()});
-  fields_.push_back(std::ref(it.first->second.first));
+  fields_.push_back(std::ref(fst->second.first));
 }
 
 record::iterator record::begin()

source/orm/sql/statement.cpp

@@ -1,6 +1,7 @@
 #include "matador/sql/statement.hpp"
 #include "matador/sql/record.hpp"
 #include "matador/sql/field.hpp"
+#include "matador/sql/query_record_result.hpp"
 
 #include <algorithm>
 #include <utility>
@@ -64,9 +65,7 @@ utils::result<query_result<record>, utils::error> statement::fetch() const {
   }
 //  logger_.info(statement_->query_.sql);
   const auto prototype = result.value()->prototype();
-    return utils::ok(query_result<record>(std::move(*result), [prototype] {
+    return utils::ok(query_result<record>(std::move(*result), prototype));
-      return detail::create_prototype<record>(prototype);
-    }));
 }
 
 utils::result<std::optional<record>, utils::error> statement::fetch_one() const {
@@ -77,15 +76,13 @@ utils::result<std::optional<record>, utils::error> statement::fetch_one() const
     }
 
     const auto prototype = result.value()->prototype();
-    query_result<record> records(std::move(*result), [prototype] {
+    query_result<record> records(std::move(*result), prototype);
-      return sql::detail::create_prototype<record>(prototype);
-    });
     auto first = records.begin();
     if (first == records.end()) {
         return utils::ok(std::optional<record>{std::nullopt});
     }
 
-    return utils::ok(std::optional{*first.get()});
+    return utils::ok(std::optional{first.release()});
 }
 
 void statement::reset() const {

test/backends/QueryBasicTest.cpp

@@ -79,7 +79,7 @@ TEST_CASE_METHOD(QueryFixture, "Insert and select basic datatypes", "[query][dat
       .from("types")
       .fetch_one<types>(db);
     REQUIRE(result.is_ok());
-    REQUIRE(*result != nullptr);
+    REQUIRE(result->get() != nullptr);
 
     REQUIRE((*result)->id_ == 1);
     REQUIRE((*result)->char_ == cval);
@@ -356,7 +356,7 @@ TEST_CASE_METHOD(QueryFixture, "Test primary key", "[query][primary key]") {
     .from("pk")
     .fetch_one<pk>(db);
   REQUIRE(row.is_ok());
-  REQUIRE(*row != nullptr);
+  REQUIRE(row->get() != nullptr);
   REQUIRE(row.value()->id > 0);
 }
 
@@ -386,7 +386,7 @@ TEST_CASE_METHOD(QueryFixture, "Test primary key prepared", "[query][primary key
 
   auto row = stmt->fetch_one<pk>();
   REQUIRE(row.is_ok());
-  REQUIRE(*row != nullptr);
+  REQUIRE(*row);
   REQUIRE(row.value()->id > 0);
   REQUIRE(row.value()->name == "george");
 }

test/backends/QueryStatementTests.cpp

@@ -70,7 +70,7 @@ TEST_CASE_METHOD(QueryFixture, "Test insert statement", "[query][statement][inse
     .fetch_one<person>(db);
   REQUIRE(row.is_ok());
 
-  REQUIRE(*row != nullptr);
+  REQUIRE(*row);
   REQUIRE((*row)->id == 1);
   REQUIRE((*row)->name == "george");
   REQUIRE((*row)->age == 45);
@@ -101,7 +101,7 @@ TEST_CASE_METHOD(QueryFixture, "Test update statement", "[query][statement][upda
     .fetch_one<person>(db);
   REQUIRE(row.is_ok());
 
-  REQUIRE(*row != nullptr);
+  REQUIRE(*row);
   REQUIRE((*row)->id == 1);
   REQUIRE((*row)->name == "george");
   REQUIRE((*row)->age == 45);
@@ -126,7 +126,7 @@ TEST_CASE_METHOD(QueryFixture, "Test update statement", "[query][statement][upda
     .fetch_one<person>(db);
   REQUIRE(row.is_ok());
 
-  REQUIRE(*row != nullptr);
+  REQUIRE(*row);
   REQUIRE((*row)->id == 1);
   REQUIRE((*row)->name == "george");
   REQUIRE((*row)->age == 36);
@@ -170,12 +170,12 @@ TEST_CASE_METHOD(QueryFixture, "Test delete statement", "[query][statement][dele
     .fetch<person>();
   REQUIRE(rows.is_ok());
 
-  for (const auto &r : *rows) {
+  for (const auto r : *rows) {
     constexpr size_t index = 1;
-    REQUIRE(r.id == peoples[index].id);
+    REQUIRE(r->id == peoples[index].id);
-    REQUIRE(r.name == peoples[index].name);
+    REQUIRE(r->name == peoples[index].name);
-    REQUIRE(r.age == peoples[index].age);
+    REQUIRE(r->age == peoples[index].age);
-    REQUIRE(r.image == peoples[index].image);
+    REQUIRE(r->image == peoples[index].image);
   }
 
   stmt = query::remove()
@@ -192,9 +192,7 @@ TEST_CASE_METHOD(QueryFixture, "Test delete statement", "[query][statement][dele
   select_stmt->reset();
   auto row = select_stmt->bind(0, "jane")
     .fetch_one<person>();
-  REQUIRE(row.is_ok());
+  REQUIRE(!row);
-
-  REQUIRE(*row == nullptr);
 
   stmt->reset();
   res = stmt->bind(0, "merlin")
@@ -205,9 +203,7 @@ TEST_CASE_METHOD(QueryFixture, "Test delete statement", "[query][statement][dele
   select_stmt->reset();
   row = select_stmt->bind(0, "merlin")
     .fetch_one<person>();
-  REQUIRE(row.is_ok());
+  REQUIRE(!row);
-
-  REQUIRE(*row == nullptr);
 }
 
 TEST_CASE_METHOD(QueryFixture, "Test reuse prepared statement", "[query][statement][reuse]") {
@@ -247,10 +243,10 @@ TEST_CASE_METHOD(QueryFixture, "Test reuse prepared statement", "[query][stateme
 
   size_t index = 0;
   for (const auto &r : *rows) {
-    REQUIRE(r.id == peoples[index].id);
+    REQUIRE(r->id == peoples[index].id);
-    REQUIRE(r.name == peoples[index].name);
+    REQUIRE(r->name == peoples[index].name);
-    REQUIRE(r.age == peoples[index].age);
+    REQUIRE(r->age == peoples[index].age);
-    REQUIRE(r.image == peoples[index].image);
+    REQUIRE(r->image == peoples[index].image);
     ++index;
   }
 
@@ -261,10 +257,10 @@ TEST_CASE_METHOD(QueryFixture, "Test reuse prepared statement", "[query][stateme
 
   index = 0;
   for (const auto &r : *rows) {
-    REQUIRE(r.id == peoples[index].id);
+    REQUIRE(r->id == peoples[index].id);
-    REQUIRE(r.name == peoples[index].name);
+    REQUIRE(r->name == peoples[index].name);
-    REQUIRE(r.age == peoples[index].age);
+    REQUIRE(r->age == peoples[index].age);
-    REQUIRE(r.image == peoples[index].image);
+    REQUIRE(r->image == peoples[index].image);
     ++index;
   }
 }

test/backends/QueryTest.cpp

@@ -27,7 +27,7 @@ using namespace matador::test;
 using namespace matador::query::meta;
 
 TEST_CASE_METHOD(QueryFixture, "Create table with foreign key relation", "[query][foreign][relation]") {
-  auto result = repo.attach<airplane>("airplane")
+  const auto result = repo.attach<airplane>("airplane")
     .and_then([this] { return repo.attach<flight>("flight");})
     .and_then([this] {return repo.create(db); });
   REQUIRE(result.is_ok());
@@ -81,9 +81,9 @@ TEST_CASE_METHOD(QueryFixture, "Execute select statement with where clause", "[q
   REQUIRE(result_person.is_ok());
 
   for (const auto &i: *result_person) {
-    REQUIRE(i.id == 7);
+    REQUIRE(i->id == 7);
-    REQUIRE(i.name == "george");
+    REQUIRE(i->name == "george");
-    REQUIRE(i.age == 45);
+    REQUIRE(i->age == 45);
   }
 }
 
@@ -143,9 +143,9 @@ TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key", "[query][for
   REQUIRE(db.exists(FLIGHT.table_name()));
 
   std::vector planes{
-    object_ptr(new airplane{1, "Airbus", "A380"}),
+    object_ptr(std::make_shared<airplane>(1, "Airbus", "A380")),
-    object_ptr(new airplane{2, "Boeing", "707"}),
+    object_ptr(std::make_shared<airplane>(2, "Boeing", "707")),
-    object_ptr(new airplane{3, "Boeing", "747"})
+    object_ptr(std::make_shared<airplane>(3, "Boeing", "747"))
   };
 
   for (const auto &plane: planes) {
@@ -163,6 +163,7 @@ TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key", "[query][for
   REQUIRE(count.is_ok());
   REQUIRE(*count == 3);
 
+
   flight f4711{4, planes.at(1), "hans"};
 
   auto res = query::insert()
@@ -192,9 +193,9 @@ TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key and join_left"
   REQUIRE(db.exists(FLIGHT.table_name()));
 
   std::vector planes{
-    object_ptr(new airplane{1, "Airbus", "A380"}),
+    object_ptr(std::make_shared<airplane>(1, "Airbus", "A380")),
-    object_ptr(new airplane{2, "Boeing", "707"}),
+    object_ptr(std::make_shared<airplane>(2, "Boeing", "707")),
-    object_ptr(new airplane{3, "Boeing", "747"})
+    object_ptr(std::make_shared<airplane>(3, "Boeing", "747"))
   };
 
   for (const auto &plane: planes) {
@@ -212,10 +213,10 @@ TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key and join_left"
   REQUIRE(count == 3);
 
   std::vector flights{
-    object_ptr(new flight{4, planes.at(0), "hans"}),
+    object_ptr(std::make_shared<flight>(4, planes.at(0), "hans")),
-    object_ptr(new flight{5, planes.at(0), "otto"}),
+    object_ptr(std::make_shared<flight>(5, planes.at(0), "otto")),
-    object_ptr(new flight{6, planes.at(1), "george"}),
+    object_ptr(std::make_shared<flight>(6, planes.at(1), "george")),
-    object_ptr(new flight{7, planes.at(2), "paul"})
+    object_ptr(std::make_shared<flight>(7, planes.at(2), "paul"))
   };
 
   for (const auto &f: flights) {
@@ -267,13 +268,15 @@ TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key and for single
     .and_then([this] {return repo.create(db); });
   REQUIRE(result.is_ok());
 
+  repo.initialize_executor(db);
+
   REQUIRE(db.exists(AIRPLANE.table_name()));
   REQUIRE(db.exists(FLIGHT.table_name()));
 
   std::vector planes{
-    object_ptr(new airplane{1, "Airbus", "A380"}),
+    object_ptr(std::make_shared<airplane>(1, "Airbus", "A380")),
-    object_ptr(new airplane{2, "Boeing", "707"}),
+    object_ptr(std::make_shared<airplane>(2, "Boeing", "707")),
-    object_ptr(new airplane{3, "Boeing", "747"})
+    object_ptr(std::make_shared<airplane>(3, "Boeing", "747"))
   };
 
   for (const auto &plane: planes) {
@@ -293,10 +296,10 @@ TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key and for single
   REQUIRE(count->value() == 3);
 
   std::vector flights{
-    object_ptr(new flight{4, planes.at(0), "hans"}),
+    object_ptr(std::make_shared<flight>(4, planes.at(0), "hans")),
-    object_ptr(new flight{5, planes.at(0), "otto"}),
+    object_ptr(std::make_shared<flight>(5, planes.at(0), "otto")),
-    object_ptr(new flight{6, planes.at(1), "george"}),
+    object_ptr(std::make_shared<flight>(6, planes.at(1), "george")),
-    object_ptr(new flight{7, planes.at(2), "paul"})
+    object_ptr(std::make_shared<flight>(7, planes.at(2), "paul"))
   };
 
   for (const auto &f: flights) {
@@ -495,8 +498,8 @@ TEST_CASE_METHOD(QueryFixture, "Test load entity with eager has many relation",
   REQUIRE(result.is_ok());
 
   const std::vector shipments {
-    object_ptr{new  shipment{1, "4711"}},
+    object_ptr{std::make_shared<shipment>(1, "4711")},
-    object_ptr{new  shipment{2, "0815"}}
+    object_ptr{std::make_shared<shipment>(2, "0815")}
   };
 
   for (const auto &sh: shipments) {
@@ -515,11 +518,11 @@ TEST_CASE_METHOD(QueryFixture, "Test load entity with eager has many relation",
   REQUIRE(*count == 2);
 
   std::vector packages {
-    object_ptr{new package{3, 15.4, shipments.at(0)}},
+    object_ptr{std::make_shared<package>(3, 15.4, shipments.at(0))},
-    object_ptr{new package{4, 1.3, shipments.at(0)}},
+    object_ptr{std::make_shared<package>(4, 1.3, shipments.at(0))},
-    object_ptr{new package{5, 30.9, shipments.at(1)}},
+    object_ptr{std::make_shared<package>(5, 30.9, shipments.at(1))},
-    object_ptr{new package{6, 22.8, shipments.at(1)}},
+    object_ptr{std::make_shared<package>(6, 22.8, shipments.at(1))},
-    object_ptr{new package{7, 17.2, shipments.at(1)}}
+    object_ptr{std::make_shared<package>(7, 17.2, shipments.at(1))}
   };
 
   for (const auto &pkg: packages) {
@@ -576,9 +579,9 @@ TEST_CASE_METHOD(QueryFixture, "Test load entity with eager has many relation",
   std::vector<size_t> packages_sizes{2, 3};
   std::cout << "\n";
   for (const auto &s : *shipment_result) {
-    REQUIRE(s.id == shipments.at(index)->id);
+    REQUIRE(s->id == shipments.at(index)->id);
-    REQUIRE(s.tracking_number == shipments.at(index)->tracking_number);
+    REQUIRE(s->tracking_number == shipments.at(index)->tracking_number);
-    REQUIRE(s.packages.size() == packages_sizes.at(index++));
+    REQUIRE(s->packages.size() == packages_sizes.at(index++));
   }
 }
 
@@ -588,17 +591,19 @@ TEST_CASE_METHOD(QueryFixture, "Test load entity with lazy belongs to relation",
     .and_then([this] {return repo.create(db); });
   REQUIRE(result.is_ok());
 
+  repo.initialize_executor(db);
+
   const std::vector deps {
-    object_ptr{new department{1, "Human Resources"}},
+    object_ptr{std::make_shared<department>(1, "Human Resources")},
-    object_ptr{new department{2, "Invoices"}}
+    object_ptr{std::make_shared<department>(2, "Invoices")}
   };
 
   const std::vector emps {
-    object_ptr{new employee{3, "Hans", "Wurst", deps[0]}},
+    object_ptr{std::make_shared<employee>(3, "Hans", "Wurst", deps[0])},
-    object_ptr{new employee{4, "Steven", "Spielberg", deps[0]}},
+    object_ptr{std::make_shared<employee>(4, "Steven", "Spielberg", deps[0])},
-    object_ptr{new employee{5, "Julia", "Roberts", deps[0]}},
+    object_ptr{std::make_shared<employee>(5, "Julia", "Roberts", deps[0])},
-    object_ptr{new employee{6, "Otto", "Walkes", deps[1]}},
+    object_ptr{std::make_shared<employee>(6, "Otto", "Walkes", deps[1])},
-    object_ptr{new employee{7, "Miss", "Marple", deps[1]}},
+    object_ptr{std::make_shared<employee>(7, "Miss", "Marple", deps[1])},
   };
 
   for (const auto &dep: deps) {
@@ -631,21 +636,26 @@ TEST_CASE_METHOD(QueryFixture, "Test load entity with lazy belongs to relation",
   REQUIRE(count.is_ok());
   REQUIRE(*count == 5);
 
-  auto emps_result = query::select({EMPLOYEE.id, EMPLOYEE.first_name, EMPLOYEE.last_name, DEPARTMENT.id, DEPARTMENT.name})
+  // auto emps_result = query::select({EMPLOYEE.id, EMPLOYEE.first_name, EMPLOYEE.last_name, DEPARTMENT.id, DEPARTMENT.name})
+  //   .from(EMPLOYEE)
+  //   .join_left(DEPARTMENT)
+  //   .on(EMPLOYEE.dep_id == DEPARTMENT.id)
+  //   .order_by(EMPLOYEE.id).asc()
+  //   .fetch_all<employee>(db);
+
+  auto emps_result = query::select({EMPLOYEE.id, EMPLOYEE.first_name, EMPLOYEE.last_name, EMPLOYEE.dep_id})
     .from(EMPLOYEE)
-    .join_left(DEPARTMENT)
-    .on(EMPLOYEE.dep_id == DEPARTMENT.id)
     .order_by(EMPLOYEE.id).asc()
     .fetch_all<employee>(db);
 
   REQUIRE(emps_result.is_ok());
   size_t index{0};
   for (const auto &e : *emps_result) {
-    REQUIRE(e.id == emps.at(index)->id);
+    REQUIRE(e->id == emps.at(index)->id);
-    REQUIRE(e.first_name == emps.at(index)->first_name);
+    REQUIRE(e->first_name == emps.at(index)->first_name);
-    REQUIRE(e.last_name == emps.at(index)->last_name);
+    REQUIRE(e->last_name == emps.at(index)->last_name);
-    REQUIRE(e.dep->id == emps.at(index)->dep->id);
+    REQUIRE(e->dep->id == emps.at(index)->dep->id);
-    REQUIRE(e.dep->name == emps.at(index)->dep->name);
+    REQUIRE(e->dep->name == emps.at(index)->dep->name);
     ++index;
   }
 }
@@ -658,21 +668,21 @@ TEST_CASE_METHOD(QueryFixture, "Test load entity with eager belongs to relation"
   } );
 
   const std::vector authors {
-    object_ptr{new author{1, "Michael", "Crichton", "23.10.1942", 1975, true, {}}},
+    object_ptr{std::make_shared<author>(1, "Michael", "Crichton", "23.10.1942", 1975, true)},
-    object_ptr{new author{ 2, "Steven", "King", "21.9.1947", 1956, false, {}}}
+    object_ptr{std::make_shared<author>( 2, "Steven", "King", "21.9.1947", 1956, false)}
   };
 
   const std::vector books {
-    object_ptr{new book{3, "Jurassic Park", authors[0], 1990}},
+    object_ptr{std::make_shared<book>(3, "Jurassic Park", authors[0], 1990)},
-    object_ptr{new book{4, "Timeline", authors[0], 1999}},
+    object_ptr{std::make_shared<book>(4, "Timeline", authors[0], 1999)},
-    object_ptr{new book{5, "The Andromeda Strain", authors[0], 1969}},
+    object_ptr{std::make_shared<book>(5, "The Andromeda Strain", authors[0], 1969)},
-    object_ptr{new book{6, "Congo", authors[0], 1980}},
+    object_ptr{std::make_shared<book>(6, "Congo", authors[0], 1980)},
-    object_ptr{new book{7, "Prey", authors[0], 2002}},
+    object_ptr{std::make_shared<book>(7, "Prey", authors[0], 2002)},
-    object_ptr{new book{8, "Carrie", authors[1], 1974}},
+    object_ptr{std::make_shared<book>(8, "Carrie", authors[1], 1974)},
-    object_ptr{new book{9, "The Shining", authors[1], 1977}},
+    object_ptr{std::make_shared<book>(9, "The Shining", authors[1], 1977)},
-    object_ptr{new book{10, "It", authors[1], 1986}},
+    object_ptr{std::make_shared<book>(10, "It", authors[1], 1986)},
-    object_ptr{new book{11, "Misery", authors[1], 1987}},
+    object_ptr{std::make_shared<book>(11, "Misery", authors[1], 1987)},
-    object_ptr{new book{12, "The Dark Tower: The Gunslinger", authors[1], 1982}},
+    object_ptr{std::make_shared<book>(12, "The Dark Tower: The Gunslinger", authors[1], 1982)},
   };
 
   for (const auto &a: authors) {
@@ -715,15 +725,15 @@ TEST_CASE_METHOD(QueryFixture, "Test load entity with eager belongs to relation"
   REQUIRE(books_result.is_ok());
   size_t index{0};
   for (const auto &b : *books_result) {
-    REQUIRE(b.id == books.at(index)->id);
+    REQUIRE(b->id == books.at(index)->id);
-    REQUIRE(b.title == books.at(index)->title);
+    REQUIRE(b->title == books.at(index)->title);
-    REQUIRE(b.book_author->id == books.at(index)->book_author->id);
+    REQUIRE(b->book_author->id == books.at(index)->book_author->id);
-    REQUIRE(b.book_author->first_name == books.at(index)->book_author->first_name);
+    REQUIRE(b->book_author->first_name == books.at(index)->book_author->first_name);
-    REQUIRE(b.book_author->last_name == books.at(index)->book_author->last_name);
+    REQUIRE(b->book_author->last_name == books.at(index)->book_author->last_name);
-    REQUIRE(b.book_author->date_of_birth == books.at(index)->book_author->date_of_birth);
+    REQUIRE(b->book_author->date_of_birth == books.at(index)->book_author->date_of_birth);
-    REQUIRE(b.book_author->year_of_birth == books.at(index)->book_author->year_of_birth);
+    REQUIRE(b->book_author->year_of_birth == books.at(index)->book_author->year_of_birth);
-    REQUIRE(b.book_author->distinguished == books.at(index)->book_author->distinguished);
+    REQUIRE(b->book_author->distinguished == books.at(index)->book_author->distinguished);
-    REQUIRE(b.published_in == books.at(index)->published_in);
+    REQUIRE(b->published_in == books.at(index)->published_in);
     ++index;
   }
 }

test/backends/SessionFixture.cpp

@@ -7,13 +7,15 @@
 namespace matador::test {
 
 SessionFixture::SessionFixture()
-: pool(connection::dns, 4)
+: ses({bus, connection::dns, 4}, schema)
-, ses({bus, pool}, schema) {}
+, db(connection::dns) {
+  REQUIRE(db.open());
+}
 
 SessionFixture::~SessionFixture() {
-  const auto conn = pool.acquire();
+  const auto result = schema.drop(db);
-  const auto result = schema.drop(*conn);
   REQUIRE(result.is_ok());
+  REQUIRE(db.close());
 }
 
 void SessionFixture::drop_table_if_exists(const std::string &table_name) const {

test/backends/SessionFixture.hpp

@@ -15,9 +15,9 @@ public:
   ~SessionFixture();
 
 protected:
-  sql::connection_pool pool;
   orm::session ses;
   utils::message_bus bus;
+  sql::connection db;
 
   query::schema schema;
 

test/backends/SessionTest.cpp

@@ -18,8 +18,7 @@ using namespace matador::test;
 TEST_CASE_METHOD(SessionFixture, "Session insert test", "[session][insert]") {
   const auto result = schema.attach<airplane>("airplanes")
     .and_then([this] {
-      const auto conn = pool.acquire();
+      return schema.create(db);
-      return schema.create(*conn);
     } );
   REQUIRE(result.is_ok());
 
@@ -37,8 +36,7 @@ TEST_CASE_METHOD(SessionFixture, "Session insert test", "[session][insert]") {
 TEST_CASE_METHOD(SessionFixture, "Session update test", "[session][update]") {
   const auto res = schema.attach<airplane>("airplanes")
     .and_then([this] {
-      const auto conn = pool.acquire();
+      return schema.create(db);
-      return schema.create(*conn);
     } );
   REQUIRE(res.is_ok());
 
@@ -69,12 +67,11 @@ TEST_CASE_METHOD(SessionFixture, "Session update test", "[session][update]") {
 
 TEST_CASE_METHOD(SessionFixture, "Session delete test", "[session][delete]") {
   const auto res = schema.attach<airplane>("airplanes")
-    .and_then([this] {
+    .and_then([this] { return schema.create(db); } );
-      const auto conn = pool.acquire();
-      return schema.create(*conn);
-    } );
   REQUIRE(res.is_ok());
 
+  schema.initialize_executor(ses);
+
   auto result = ses.insert<airplane>(1, "Boeing", "747");
   REQUIRE(result.is_ok());
 
@@ -94,10 +91,7 @@ TEST_CASE_METHOD(SessionFixture, "Session delete test", "[session][delete]") {
 TEST_CASE_METHOD(SessionFixture, "Session relation test", "[session][relation]") {
   const auto result = schema.attach<airplane>("airplanes")
     .and_then([this] { return schema.attach<flight>("flights"); } )
-    .and_then([this] {
+    .and_then([this] { return schema.create(db); } );
-      const auto conn = pool.acquire();
-      return schema.create(*conn);
-    } );
   REQUIRE(result.is_ok());
 
   auto plane = ses.insert<airplane>(1, "Boeing", "A380");
@@ -118,10 +112,7 @@ TEST_CASE_METHOD(SessionFixture, "Session relation test", "[session][relation]")
 
 TEST_CASE_METHOD(SessionFixture, "Use session to find object with id", "[session][find]") {
   const auto result = schema.attach<airplane>("airplanes")
-    .and_then([this] {
+    .and_then([this] { return schema.create(db); } );
-      const auto conn = pool.acquire();
-      return schema.create(*conn);
-    } );
   REQUIRE(result.is_ok());
 
   auto a380 = ses.insert<airplane>(1, "Boeing", "A380");
@@ -141,8 +132,7 @@ TEST_CASE_METHOD(SessionFixture, "Use session to find object with id", "[session
 TEST_CASE_METHOD(SessionFixture, "Use session to find all objects", "[session][find]") {
   const auto result = schema.attach<airplane>("airplanes")
     .and_then([this] {
-      const auto conn = pool.acquire();
+      return schema.create(db);
-      return schema.create(*conn);
     } );
   REQUIRE(result.is_ok());
 
@@ -167,9 +157,9 @@ TEST_CASE_METHOD(SessionFixture, "Use session to find all objects", "[session][f
   auto all_planes = find_result.release();
   size_t index {0};
   for (const auto &i: all_planes) {
-    REQUIRE(i.id == std::get<0>(expected_result[index]));
+    REQUIRE(i->id == std::get<0>(expected_result[index]));
-    REQUIRE(i.brand == std::get<1>(expected_result[index]));
+    REQUIRE(i->brand == std::get<1>(expected_result[index]));
-    REQUIRE(i.model == std::get<2>(expected_result[index]));
+    REQUIRE(i->model == std::get<2>(expected_result[index]));
     ++index;
   }
 }
@@ -177,17 +167,16 @@ TEST_CASE_METHOD(SessionFixture, "Use session to find all objects", "[session][f
 TEST_CASE_METHOD(SessionFixture, "Use session to find all objects with one-to-many lazy relation", "[session][find][one-to-many][eager]") {
   auto result = schema.attach<author>("authors")
     .and_then( [this] { return schema.attach<book>("books"); } )
-    .and_then([this] {
+    .and_then([this] { return schema.create(db); } );
-      const auto conn = pool.acquire();
-      return schema.create(*conn);
-    } );
 
-  std::vector<std::unique_ptr<author>> authors;
+  schema.initialize_executor(ses);
-  authors.emplace_back(new author{1, "Michael", "Crichton", "23.10.1942", 1975, true, {}});
+  std::vector authors {
-  authors.emplace_back(new author{ 2, "Steven", "King", "21.9.1947", 1956, false, {}});
+    object_ptr{std::make_shared<author>(1, "Michael", "Crichton", "23.10.1942", 1975, true)},
+    object_ptr{std::make_shared<author>( 2, "Steven", "King", "21.9.1947", 1956, false)}
+  };
 
-  for (auto &&a: authors) {
+  for (const auto &a: authors) {
-      auto res = ses.insert(a.release());
+      auto res = ses.insert(a);
       REQUIRE(res.is_ok());
   }
 
@@ -197,7 +186,7 @@ TEST_CASE_METHOD(SessionFixture, "Use session to find all objects with one-to-ma
   std::vector<object_ptr<author>> author_repo;
   for (auto it = all_authors.begin(); it != all_authors.end(); ++it) {
       std::cout << "author: " << it->first_name << " (books: " << it->books.size() << ")\n";
-      author_repo.emplace_back(it.release());
+      author_repo.emplace_back(it.optr());
   }
   REQUIRE(author_repo.size() == 2);
 
@@ -231,13 +220,12 @@ TEST_CASE_METHOD(SessionFixture, "Use session to find all objects with one-to-ma
   auto result = schema.attach<department>("departments")
     .and_then( [this] { return schema.attach<employee>("employees"); } )
     .and_then([this] {
-      const auto conn = pool.acquire();
+      return schema.create(db);
-      return schema.create(*conn);
     } );
 
   std::vector<std::unique_ptr<department>> departments;
-  departments.emplace_back(new department{1, "Insurance", {}});
+  departments.emplace_back(new department{1, "Insurance"});
-  departments.emplace_back(new department{2, "Invoice", {}});
+  departments.emplace_back(new department{2, "Invoice"});
 
   for (auto &&a: departments) {
     auto res = ses.insert(a.release());
@@ -250,7 +238,7 @@ TEST_CASE_METHOD(SessionFixture, "Use session to find all objects with one-to-ma
   std::vector<object_ptr<department>> departments_repo;
   for (auto it = all_departments.begin(); it != all_departments.end(); ++it) {
     std::cout << "department: " << it->name << " (employees: " << it->employees.size() << ")\n";
-    departments_repo.emplace_back(it.release());
+    departments_repo.emplace_back(it.optr());
   }
   REQUIRE(departments_repo.size() == 2);
 
@@ -287,8 +275,7 @@ TEST_CASE_METHOD(SessionFixture, "Use session to find all objects with many-to-m
   auto result = schema.attach<recipe>("recipes")
     .and_then( [this] { return schema.attach<ingredient>("ingredients"); } )
     .and_then([this] {
-      const auto conn = pool.acquire();
+      return schema.create(db);
-      return schema.create(*conn);
     } );
 
   std::vector<std::unique_ptr<ingredient>> ingredients;

test/backends/StatementTest.cpp

@@ -21,24 +21,18 @@ using namespace matador::query;
 using namespace matador::test;
 using namespace matador::query::meta;
 
-namespace matador::test::detail {
-template<class Type, typename... Args>
-[[maybe_unused]] object_ptr<Type> make_object_ptr(Args&&... args) {
-  return object_ptr(new Type(std::forward<Args>(args)...));
-}
-}
-
 class StatementTestFixture : public QueryFixture {
 public:
   StatementTestFixture() {
     REQUIRE(repo.attach<airplane>("airplanes"));
+    repo.initialize_executor(db);
   }
 
 protected:
-  std::vector<object_ptr<airplane>> planes{
+  std::vector<airplane> planes {
-    matador::test::detail::make_object_ptr<airplane>(1, "Airbus", "A380"),
+    {1, "Airbus", "A380"},
-    matador::test::detail::make_object_ptr<airplane>(2, "Boeing", "707"),
+    {2, "Boeing", "707"},
-    matador::test::detail::make_object_ptr<airplane>(3, "Boeing", "747")
+    {3, "Boeing", "747"}
   };
 };
 
@@ -53,7 +47,7 @@ TEST_CASE_METHOD(StatementTestFixture, "Create prepared statement", "[statement]
     REQUIRE(stmt.is_ok());
 
     for (const auto &plane: planes) {
-      auto res = stmt->bind(*plane).execute();
+      auto res = stmt->bind(plane).execute();
       REQUIRE(res.is_ok());
       REQUIRE(*res == 1);
       stmt->reset();
@@ -66,9 +60,9 @@ TEST_CASE_METHOD(StatementTestFixture, "Create prepared statement", "[statement]
     REQUIRE(result.is_ok());
     size_t index{0};
     for (const auto &i: *result) {
-      REQUIRE(i.id == planes[index]->id);
+      REQUIRE(i->id == planes[index].id);
-      REQUIRE(i.brand == planes[index]->brand);
+      REQUIRE(i->brand == planes[index].brand);
-      REQUIRE(i.model == planes[index++]->model);
+      REQUIRE(i->model == planes[index++].model);
     }
   }
 
@@ -76,13 +70,13 @@ TEST_CASE_METHOD(StatementTestFixture, "Create prepared statement", "[statement]
     for (const auto &plane: planes) {
       auto res = query::insert()
         .into(AIRPLANE, {AIRPLANE.id, AIRPLANE.brand, AIRPLANE.model})
-        .values(*plane)
+        .values(plane)
         .execute(db);
       REQUIRE(res.is_ok());
       REQUIRE(*res == 1);
     }
 
-    auto stmt = query::select(generator::columns<airplane>(repo))
+    auto stmt = query::select({AIRPLANE.id, AIRPLANE.brand, AIRPLANE.model})
       .from(AIRPLANE)
       .where(AIRPLANE.brand == _)
       .prepare(db);
@@ -93,9 +87,9 @@ TEST_CASE_METHOD(StatementTestFixture, "Create prepared statement", "[statement]
 
     REQUIRE(result.is_ok());
     for (const auto &i: *result) {
-      REQUIRE(i.id == planes[0]->id);
+      REQUIRE(i->id == planes[0].id);
-      REQUIRE(i.brand == planes[0]->brand);
+      REQUIRE(i->brand == planes[0].brand);
-      REQUIRE(i.model == planes[0]->model);
+      REQUIRE(i->model == planes[0].model);
     }
 
     stmt->reset();
@@ -106,9 +100,9 @@ TEST_CASE_METHOD(StatementTestFixture, "Create prepared statement", "[statement]
     size_t index{1};
     REQUIRE(result.is_ok());
     for (const auto &i: *result) {
-      REQUIRE(i.id == planes[index]->id);
+      REQUIRE(i->id == planes[index].id);
-      REQUIRE(i.brand == planes[index]->brand);
+      REQUIRE(i->brand == planes[index].brand);
-      REQUIRE(i.model == planes[index++]->model);
+      REQUIRE(i->model == planes[index++].model);
     }
   }
 }

test/models/author.hpp

@@ -12,6 +12,13 @@ namespace matador::test {
 struct book;
 
 struct author {
+  author() = default;
+  author(const unsigned int id, std::string first_name, std::string last_name, std::string date_of_birth, const unsigned short year_of_birth, const bool distinguished)
+  : id(id), first_name(std::move(first_name))
+  , last_name(std::move(last_name))
+  , date_of_birth(std::move(date_of_birth))
+  , year_of_birth(year_of_birth)
+  , distinguished(distinguished) {}
   unsigned int id{};
   std::string first_name;
   std::string last_name;

test/models/book.hpp

@@ -12,6 +12,9 @@ namespace matador::test {
 struct author;
 
 struct book {
+  book() = default;
+  book(const unsigned int id, std::string title, object::object_ptr<author> author, unsigned short published_in)
+  : id(id), title(std::move(title)), book_author(std::move(author)), published_in(published_in) {}
   unsigned int id{};
   std::string title;
   object::object_ptr<author> book_author;

test/models/department.hpp

@@ -11,6 +11,9 @@ namespace matador::test {
 struct employee;
 
 struct department {
+    department() = default;
+    department(const unsigned int id, std::string name)
+    : id(id), name(std::move(name)) {}
     unsigned int id{};
     std::string name;
     std::vector<object::object_ptr<employee>> employees{};
@@ -27,6 +30,9 @@ struct department {
 };
 
 struct employee {
+    employee() = default;
+    employee(const unsigned int id, std::string first, std::string last, object::object_ptr<department> dep)
+    : id(id), first_name(std::move(first)), last_name(std::move(last)), dep(std::move(dep)) {}
     unsigned int id{};
     std::string first_name;
     std::string last_name;

test/models/product.hpp

@@ -5,7 +5,6 @@
 #include "supplier.hpp"
 
 #include "matador/utils/access.hpp"
-#include "matador/utils/cascade_type.hpp"
 
 #include "matador/object/object_ptr.hpp"
 
@@ -14,8 +13,8 @@
 namespace matador::test {
 struct product {
   std::string product_name;
-  object::object_ptr<supplier> supplier;
+  object::object_ptr<supplier> seller;
-  object::object_ptr<category> category;
+  object::object_ptr<category> type;
   std::string quantity_per_unit;
   unsigned int unit_price;
   unsigned int units_in_stock;
@@ -28,8 +27,8 @@ struct product {
     namespace field = matador::access;
     using namespace matador::utils;
     field::primary_key(op, "product_name", product_name, 255);
-    field::belongs_to(op, "supplier_id", supplier, CascadeAllFetchLazy);
+    field::belongs_to(op, "supplier_id", seller, CascadeAllFetchLazy);
-    field::belongs_to(op, "category_id", category, CascadeAllFetchLazy);
+    field::belongs_to(op, "category_id", type, CascadeAllFetchLazy);
     field::attribute(op, "quantity_per_unit", quantity_per_unit, 255);
     field::attribute(op, "unit_price", unit_price);
     field::attribute(op, "units_in_stock", units_in_stock);

test/models/shipment.hpp

@@ -13,6 +13,10 @@ namespace matador::test {
 struct package;
 
 struct shipment {
+  shipment() = default;
+  shipment(const long id, std::string tracking_number)
+  : id(id), tracking_number(std::move(tracking_number)) {}
+
   long id{};
   std::string tracking_number;
   object::collection<object::object_ptr<package> > packages{};
@@ -27,6 +31,10 @@ struct shipment {
 };
 
 struct package {
+  package() = default;
+  package(const long id, double weight, object::object_ptr<shipment> del)
+  : id(id), weight(weight), delivery(std::move(del)){}
+
   long id{};
   double weight{};
   object::object_ptr<shipment> delivery;

test/orm/backend/test_connection.cpp

@@ -49,7 +49,10 @@ utils::result<size_t, utils::error> test_connection::execute(const std::string &
 }
 
 utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> test_connection::fetch(const sql::query_context &context) {
-  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<test_result_reader>(), context.prototype, context.prototype.size()));
+  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<test_result_reader>(),
+                                                            context.prototype,
+                                                            context.resolver_factory,
+                                                            context.prototype.size()));
 }
 
 utils::result<std::unique_ptr<sql::statement_impl>, utils::error> test_connection::prepare(const sql::query_context &context) {
@@ -61,12 +64,12 @@ utils::result<std::vector<object::attribute>, utils::error> test_connection::des
   return utils::ok(std::vector<object::attribute>{});
 }
 
-utils::result<bool, utils::error> test_connection::exists(const std::string &/*schema_name*/, const std::string &/*table_name*/) {
+utils::result<bool, utils::error> test_connection::exists(const std::string &/*schema_name*/,
+                                                          const std::string &/*table_name*/) {
   return utils::ok(false);
 }
 
 std::string test_connection::to_escaped_string(const utils::blob_type_t &value) const {
   return utils::to_string(value);
 }
-
 }

test/orm/backend/test_statement.cpp

@@ -19,7 +19,10 @@ utils::result<size_t, utils::error> test_statement::execute(const sql::parameter
 }
 
 utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> test_statement::fetch(const sql::parameter_binder &/*bindings*/) {
-  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<test_result_reader>(), query_.prototype, query_.prototype.size()));
+  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<test_result_reader>(),
+    query_.prototype,
+    query_.resolver_factory,
+    query_.prototype.size()));
 }
 
 void test_statement::reset() {}

test/orm/orm/SessionQueryBuilderTest.cpp

@@ -12,11 +12,8 @@
 #include "matador/query/table.hpp"
 #include "matador/query/schema.hpp"
 
-#include "matador/utils/macro_map.hpp"
+#include "matador/query/query_builder.hpp"
 
-#include "matador/orm/session_query_builder.hpp"
-
-#include "../backend/test_connection.hpp"
 #include "../backend/test_backend_service.hpp"
 
 #include "../../models/airplane.hpp"
@@ -29,7 +26,6 @@
 #include "../../models/student.hpp"
 
 using namespace matador::object;
-using namespace matador::orm;
 using namespace matador::query;
 using namespace matador::utils;
 using namespace matador::sql;
@@ -46,7 +42,7 @@ TEST_CASE("Create sql query data for entity with eager has one", "[query][entity
     .and_then( [&scm] { return scm.attach<flight>("flights"); } );
   REQUIRE(result);
 
-  session_query_builder eqb(scm, db);
+  query_builder eqb(scm, db);
 
   const auto it = scm.find(typeid(flight));
   REQUIRE(it != scm.end());
@@ -100,7 +96,7 @@ TEST_CASE("Create sql query data for entity with eager belongs to", "[query][ent
     .and_then( [&scm] { return scm.attach<book>("books"); } );
   REQUIRE(result);
 
-  session_query_builder eqb(scm, db);
+  query_builder eqb(scm, db);
 
   const auto it = scm.find(typeid(book));
   REQUIRE(it != scm.end());
@@ -172,7 +168,7 @@ TEST_CASE("Create sql query data for entity with eager has many belongs to", "[q
     .and_then( [&scm] { return scm.attach<order>("orders"); } );
   REQUIRE(result);
 
-  session_query_builder eqb(scm, db);
+  query_builder eqb(scm, db);
 
   const auto it = scm.find(typeid(order));
   REQUIRE(it != scm.end());
@@ -236,7 +232,7 @@ TEST_CASE("Create sql query data for entity with eager many to many", "[query][e
     .and_then( [&scm] { return scm.attach<ingredient>("ingredients"); } );
   REQUIRE(result);
 
-  session_query_builder eqb(scm, db);
+  query_builder eqb(scm, db);
 
   const auto it = scm.find(typeid(ingredient));
   REQUIRE(it != scm.end());
@@ -290,7 +286,7 @@ TEST_CASE("Create sql query data for entity with eager many to many (inverse par
     .and_then( [&scm] { return scm.attach<course>("courses"); } );
   REQUIRE(result);
 
-  session_query_builder eqb(scm, db);
+  query_builder eqb(scm, db);
 
   const auto it = scm.find(typeid(course));
   REQUIRE(it != scm.end());
@@ -344,7 +340,7 @@ TEST_CASE("Test eager relationship", "[session][eager]") {
     .and_then( [&scm] { return scm.attach<employee>("employees"); } );
   REQUIRE(result);
 
-  session_query_builder eqb(scm, db);
+  query_builder eqb(scm, db);
 
   auto data = eqb.build<department>();
   REQUIRE(data.is_ok());