Merge remote-tracking branch 'origin/feature/matador-ng' into feature/matador-ng

This reverts commit 8914c06833.

include/matador/object/attribute.hpp

@@ -34,6 +34,7 @@ public:
   [[nodiscard]] const std::string& name() const;
   void name(const std::string& n);
   [[nodiscard]] std::string full_name() const;
+  [[nodiscard]] size_t index() const;
   [[nodiscard]] const utils::field_attributes& attributes() const;
   [[nodiscard]] utils::field_attributes& attributes();
   [[nodiscard]] bool is_nullable() const;
@@ -68,6 +69,7 @@ private:
   friend class object_generator;
 
   std::string name_;
+  size_t index_{0};
   std::weak_ptr<object> owner_;
   utils::basic_type type_{utils::basic_type::Null};
   utils::field_attributes options_{};

include/matador/object/basic_object_info.hpp

@@ -27,12 +27,12 @@ public:
   [[nodiscard]] std::type_index type_index() const;
   [[nodiscard]] std::string name() const;
   [[nodiscard]] std::shared_ptr<class object> object() const;
-  [[nodiscard]] const std::list<attribute>& attributes() const;
-  [[nodiscard]] const std::list<class restriction>& constraints() const;
+  [[nodiscard]] const std::vector<attribute>& attributes() const;
+  [[nodiscard]] const std::list<restriction>& constraints() const;
 
   [[nodiscard]] bool has_primary_key() const;
   [[nodiscard]] const utils::identifier& primary_key() const;
-  [[nodiscard]]  attribute* primary_key_attribute() const;
+  [[nodiscard]] const attribute* primary_key_attribute() const;
 
   void update_name(const std::string& name) const;
 

include/matador/object/basic_repository.hpp

@@ -95,7 +95,7 @@ public:
     return basic_info(std::type_index(typeid(Type)));
   }
 
-  [[nodiscard]] utils::result<attribute*, utils::error> primary_key_attribute(const std::type_index &ti) const;
+  [[nodiscard]] utils::result<const attribute*, utils::error> primary_key_attribute(const std::type_index &ti) const;
 
   void dump(std::ostream &os) const;
   static void dump(std::ostream &os, const repository_node& node);

include/matador/object/collection.hpp

@@ -21,31 +21,31 @@ public:
   collection(const collection& other) = default;
 
   void push_back(const value_type& value) {
-    proxy_->items().push_back(value);
+    proxy_->push_back(value);
   }
 
   iterator begin() {
-    return proxy_->items().begin();
+    return proxy_->begin();
   }
 
   iterator end() {
-    return proxy_->items().end();
+    return proxy_->end();
   }
 
   const_iterator begin() const {
-    return proxy_->items().begin();
+    return proxy_->begin();
   }
 
   const_iterator end() const {
-    return proxy_->items().end();
+    return proxy_->end();
   }
 
   [[nodiscard]] size_t size() const {
-    return proxy_->items().size();
+    return proxy_->size();
   }
 
   [[nodiscard]] bool empty() const {
-    return proxy_->items().empty();
+    return proxy_->empty();
   }
 
   void reset(std::shared_ptr<collection_proxy<Type>> proxy) {
@@ -53,7 +53,7 @@ public:
   }
 
 private:
-  std::shared_ptr<collection_proxy<Type>> proxy_;
+  std::shared_ptr<abstract_collection_proxy<Type>> proxy_;
 };
 
 }

include/matador/object/collection_proxy.hpp

@@ -1,8 +1,8 @@
 #ifndef MATADOR_COLLECTION_PROXY_HPP
 #define MATADOR_COLLECTION_PROXY_HPP
 
-
 #include "matador/object/collection_resolver.hpp"
+#include "matador/object/many_to_many_relation.hpp"
 
 #include "matador/utils/identifier.hpp"
 
@@ -12,13 +12,99 @@
 
 namespace matador::object {
 
+// has many primitive
+// relation<OwnerType, PrimitiveType>
+// has many ptr
+// relation<OwnerType, ObjectType>
+// has many to many
+// relation<OwnerType, ForeignType>
 
-template<typename Type>
-class collection_proxy final {
+template < class RelationType >
+struct relation_iterator_traits {
+  static RelationType& value(RelationType& item) {
+    return item;
+  }
+};
+
+template < typename Type, typename OwnerType >
+struct relation_iterator_traits<relation<OwnerType, Type>> {
+  static Type& value(relation<OwnerType, Type>& re) {
+    return re.relation().value();
+  }
+};
+
+template<typename Type, typename RelationType = Type>
+class collection_proxy_iterator {
 public:
   using value_type = Type;
-  using iterator = typename std::vector<value_type>::iterator;
-  using const_iterator = typename std::vector<value_type>::const_iterator;
+  using reference = Type&;
+  using pointer = Type*;
+  using relation_type = RelationType;
+  using iterator_category = std::forward_iterator_tag;
+
+  collection_proxy_iterator() = default;
+  collection_proxy_iterator(typename std::vector<RelationType>::iterator it)
+  : it_(it) {}
+
+  reference operator*() {
+    return relation_iterator_traits<relation_type>::value(*it_);
+  }
+
+  pointer operator->() {
+    return &relation_iterator_traits<relation_type>::value(*it_);
+  }
+
+  collection_proxy_iterator& operator++() {
+    ++it_;
+    return *this;
+  }
+  bool operator==(const collection_proxy_iterator& other) const {
+    return it_ == other.it_;
+  }
+  bool operator!=(const collection_proxy_iterator& other) const {
+    return !operator==(other);
+  }
+
+  // relation_type& relation() {
+
+    // return *it_;
+  // }
+private:
+  typename std::vector<RelationType>::iterator it_;
+};
+
+template<typename Type, typename RelationType = Type>
+class abstract_collection_proxy {
+public:
+  using value_type = Type;
+  using relation_type = RelationType;
+  // using iterator = typename std::vector<value_type>::iterator;
+  // using const_iterator = typename std::vector<value_type>::const_iterator;
+  using iterator = collection_proxy_iterator<value_type, relation_type>;
+  using const_iterator = collection_proxy_iterator<value_type, relation_type>;
+
+  virtual ~abstract_collection_proxy() = default;
+
+  virtual void push_back(const value_type& value) = 0;
+
+  virtual iterator begin() = 0;
+  virtual iterator end() = 0;
+
+  [[nodiscard]] virtual size_t size() = 0;
+  [[nodiscard]] virtual bool empty() = 0;
+
+  [[nodiscard]] virtual const utils::identifier& owner_id() const = 0;
+
+protected:
+  std::vector<relation_type> items_;
+};
+
+template<typename Type>
+class collection_proxy : public abstract_collection_proxy<Type> {
+public:
+  using value_type = Type;
+  using iterator = typename abstract_collection_proxy<Type>::iterator;
+  using const_iterator = typename abstract_collection_proxy<Type>::const_iterator;
 
   collection_proxy() = default;
 
@@ -34,17 +120,32 @@ public:
   explicit collection_proxy(std::vector<Type> items)
   : items_(std::move(items)) {}
 
-  [[nodiscard]] const utils::identifier& owner_id() const {
+  [[nodiscard]] const utils::identifier& owner_id() const override {
     return owner_id_;
   }
-  const std::vector<Type>& items() const {
+
+  iterator begin() override {
     resolve();
-    return items_;
+    return items_.begin();
   }
-  std::vector<Type>& items() {
+  iterator end() override {
     resolve();
-    return items_;
+    return items_.end();
   }
+
+  void push_back(const value_type& value) override {
+    resolve();
+    items_.push_back(value);
+  }
+  [[nodiscard]] size_t size() override {
+    resolve();
+    return items_.size();
+  }
+  [[nodiscard]] bool empty() override {
+    resolve();
+    return items_.empty();
+  }
+
 private:
   void resolve() {
     if (loaded_) {
@@ -70,5 +171,18 @@ private:
   std::weak_ptr<collection_resolver<Type>> resolver_{};
   mutable std::mutex mutex_{};
 };
+
+template<typename Type, class OwnerType>
+class collection_many_to_many_proxy {
+public:
+  using value_type = Type;
+  using owner_type = OwnerType;
+  using relation_type = many_to_many_relation<value_type, owner_type>;
+  using iterator = typename std::vector<relation_type>::iterator;
+  using const_iterator = typename std::vector<relation_type>::const_iterator;
+
+private:
+  std::vector<relation_type> relations_;
+};
 }
 #endif //MATADOR_COLLECTION_PROXY_HPP

include/matador/object/many_to_many_relation.hpp

@@ -8,6 +8,48 @@
 
 namespace matador::object {
 
+template < class LocalType, class ForeignType >
+class relation {
+public:
+    relation() = default;
+    relation(std::string local_name, std::string remote_name)
+    : local_name_(std::move(local_name))
+    , remote_name_(std::move(remote_name)) {}
+    relation(std::string local_name, std::string remote_name, const object_ptr<LocalType>& local, const ForeignType& remote)
+    : local_name_(std::move(local_name))
+    , remote_name_(std::move(remote_name))
+    , local_(local)
+    , remote_(remote)
+    {}
+
+    template<class Operator>
+    void process(Operator &op) {
+        namespace field = matador::access;
+        field::belongs_to(op, local_name_.c_str(), local_, utils::CascadeNoneFetchLazy);
+        foreign_field(op);
+    }
+
+    object_ptr<LocalType> local() const { return local_; }
+    const ForeignType& remote() const { return remote_; }
+
+private:
+  template<typename Operator, class RemoteType = ForeignType>
+  void foreign_field(Operator &op, std::enable_if_t<!is_object_ptr<RemoteType>::value>* /*unused*/) {
+        namespace field = matador::access;
+        field::attribute(op, remote_name_.c_str(), remote_);
+  }
+  template<typename Operator, class RemoteType = ForeignType>
+  void foreign_field(Operator &op, std::enable_if_t<is_object_ptr<RemoteType>::value>* /*unused*/) {
+        namespace field = matador::access;
+        field::belongs_to(op, remote_name_.c_str(), remote_, utils::CascadeNoneFetchLazy);
+  }
+private:
+    std::string local_name_;
+    std::string remote_name_;
+    object_ptr<LocalType> local_;
+    ForeignType remote_;
+};
+
 template < class LocalType, class ForeignType >
 class many_to_many_relation {
 public:

include/matador/object/object.hpp

@@ -17,17 +17,21 @@ public:
 
   static const attribute& create_attribute(std::string name, const std::shared_ptr<object>& obj);
 
-  [[nodiscard]] attribute* primary_key_attribute() const;
+  [[nodiscard]] const attribute* primary_key_attribute() const;
   [[nodiscard]] const utils::identifier& primary_key() const;
   [[nodiscard]] bool has_primary_key() const;
 
+  [[nodiscard]] bool is_relation_object() const;
+  [[nodiscard]] const attribute* join_attribute() const;
+  [[nodiscard]] const attribute* inverse_join_attribute() const;
+
   [[nodiscard]] const std::string& name() const;
 
   void update_name(const std::string& name);
 
   [[nodiscard]] bool has_attributes() const;
   [[nodiscard]] size_t attribute_count() const;
-  [[nodiscard]] const std::list<attribute>& attributes() const;
+  [[nodiscard]] const std::vector<attribute>& attributes() const;
 
   [[nodiscard]] bool has_constraints() const;
   [[nodiscard]] size_t constraint_count() const;
@@ -40,9 +44,12 @@ private:
   friend class object_generator;
 
   std::string name_;
-  attribute* pk_attribute_{nullptr};
+  int pk_column_index_{-1};
+  int join_column_index_{-1};
+  int inverse_join_column_index_{-1};
+
   utils::identifier pk_identifier_;
-  std::list<attribute> attributes_;
+  std::vector<attribute> attributes_;
   std::list<restriction> constraints_;
 };
 }

include/matador/object/object_generator.hpp

@@ -58,7 +58,11 @@ public:
     }
 
     template < class Type >
-    static std::shared_ptr<object> generate(std::unique_ptr<Type>&& t, basic_repository &repo, const std::string &name) {
+    static std::shared_ptr<object> generate(std::unique_ptr<Type>&& t,
+                                            basic_repository &repo,
+                                            const std::string &name,
+                                            const std::string &join_column = "",
+                                            const std::string &inverse_join_column = "") {
         const std::type_index ti(typeid(Type));
         if (repo.has_object_for_type(ti)) {
             auto obj = repo.object_for_type(ti);
@@ -71,6 +75,9 @@ public:
         std::ignore = repo.provide_object_in_advance(ti, obj);
         object_generator gen(repo, obj);
         access::process(gen, *t);
+        if (!join_column.empty() && !inverse_join_column.empty()) {
+            gen.prepare_relation_table(join_column, inverse_join_column);
+        }
         return obj;
     }
 
@@ -98,6 +105,7 @@ public:
     void on_foreign_key(const char *id, Pointer &/*x*/) {
         const auto type = pk_type_determinator::determine<typename Pointer::value_type>();
         auto &ref = object_->attributes_.emplace_back(id, type, utils::constraints::ForeignKey, null_option_type::NotNull);
+        ref.index_ = object_->attributes_.size() - 1;
         ref.owner_ = object_;
     }
     template<class ContainerType>
@@ -111,6 +119,7 @@ private:
     template<typename ValueType>
     attribute &emplace_attribute(const char *id, const utils::field_attributes& attr, null_option_type null_option) {
         auto &ref = object_->attributes_.emplace_back(id, utils::data_type_traits<ValueType>::type(attr.size()), attr, null_option);
+        ref.index_ = object_->attributes_.size() - 1;
         ref.owner_ = object_;
         return ref;
     }
@@ -120,9 +129,10 @@ private:
     void create_fk_constraint(const std::string& name) const;
     void create_unique_constraint(const std::string& name) const;
 
-    [[nodiscard]] std::list<attribute>::iterator find_attribute_by_name(const std::string &name) const;
+    [[nodiscard]] std::vector<attribute>::iterator find_attribute_by_name(const std::string &name) const;
 
-    void prepare_primary_key(attribute &ref, utils::identifier &&pk) const;
+    void prepare_primary_key(const attribute &ref, utils::identifier &&pk) const;
+    void prepare_relation_table(const std::string &join_column, const std::string &inverse_join_column) const;
 
     template<typename Type>
     [[nodiscard]] std::shared_ptr<object> fk_object() const;
@@ -135,7 +145,7 @@ private:
 
 template<typename ValueType>
 void object_generator::on_primary_key(const char *id, ValueType &x, const utils::primary_key_attribute& attr) {
-    utils::constraints cs = utils::constraints::PrimaryKey;
+    auto cs = utils::constraints::PrimaryKey;
     if (attr.generator() == utils::generator_type::Identity) {
         cs |= utils::constraints::Identity;
     }
@@ -160,7 +170,7 @@ void object_generator::create_fk_constraint(const std::string& name) const {
         return;
     }
     const auto obj = fk_object<Type>();
-    restriction pk_constraint(*pk_attr);
+    restriction pk_constraint(pk_attr->index());
     pk_constraint.options_ |= utils::constraints::ForeignKey;
     pk_constraint.owner_ = object_;
     pk_constraint.reference_ = obj;

include/matador/object/object_proxy.hpp

@@ -26,31 +26,37 @@ public:
 
   // Lazy
   object_proxy(std::weak_ptr<object_resolver<Type>> resolver, utils::identifier id)
-  : resolver_(resolver)
-  , pk_(std::move(id)) {
+  : resolver_(std::move(resolver))
+  , pk_(std::move(id))
+  , state_(object_state::Persistent) {
   }
 
   // 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)
-  , state_(object_state::Persistent){
+  : obj_(std::move(obj))
+  , resolver_(std::move(resolver))
+  , pk_(obj_ ? primary_key_resolver::resolve_object(*obj_).pk : utils::identifier{})
+  , state_(obj_ ? object_state::Persistent : object_state::Detached) {
   }
 
   // Transient
   explicit object_proxy(std::shared_ptr<Type> obj)
-  : obj_(obj)
-  , pk_(primary_key_resolver::resolve_object(*obj).pk) {
+  : obj_(std::move(obj))
+  , pk_(obj_ ? primary_key_resolver::resolve_object(*obj_).pk : utils::identifier{}) {
   }
 
   void attach(std::shared_ptr<Type> obj) {
     std::lock_guard lock(mutex_);
+
     obj_ = std::move(obj);
-    if (obj_) {
-      pk_ = primary_key_resolver::resolve_object(*obj_).pk;
-      state_.store(object_state::Persistent, std::memory_order_release);
+    if (!obj_) {
+      pk_.clear();
+      state_ = object_state::Detached;
+      return;
     }
+
+    pk_ = primary_key_resolver::resolve_object(*obj_).pk;
+    state_ = object_state::Persistent;
   }
 
   void resolver(std::weak_ptr<object_resolver<Type>> resolver) {
@@ -59,66 +65,125 @@ public:
   }
 
   [[nodiscard]] std::shared_ptr<Type> object() const {
-    if (!obj_) {
-      std::ignore = resolve();
-    }
-    return obj_;
+    return resolve_object();
   }
 
   void invalidate() {
     std::lock_guard lock(mutex_);
     obj_.reset();
     resolver_.reset();
-    state_.store(object_state::Detached, std::memory_order_release);
+    state_ = object_state::Detached;
   }
 
   [[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 *operator->() {
+    auto *ptr = pointer();
+    if (!ptr) {
+      throw std::runtime_error("Cannot dereference empty object proxy");
+    }
+    return ptr;
+  }
 
-  Type *pointer() const { return resolve(); }
+  const Type *operator->() const {
+    auto *ptr = pointer();
+    if (!ptr) {
+      throw std::runtime_error("Cannot dereference empty object proxy");
+    }
+    return ptr;
+  }
+
+  Type &operator*() {
+    auto *ptr = pointer();
+    if (!ptr) {
+      throw std::runtime_error("Cannot dereference empty object proxy");
+    }
+    return *ptr;
+  }
+
+  const Type &operator*() const {
+    auto *ptr = pointer();
+    if (!ptr) {
+      throw std::runtime_error("Cannot dereference empty object proxy");
+    }
+    return *ptr;
+  }
+
+  Type *pointer() const {
+    return resolve_object().get();
+  }
+
+  [[nodiscard]] bool empty() const {
+    std::lock_guard lock(mutex_);
+    return !obj_ && resolver_.expired();
+  }
 
-  [[nodiscard]] bool empty() const { return !obj_ && resolver_.expired(); }
   [[nodiscard]] bool valid() const { return !empty(); }
-  [[nodiscard]] bool has_primary_key() const { return !pk_.is_null(); }
-  [[nodiscard]] const utils::identifier &primary_key() const { return pk_; }
-  void primary_key(const utils::identifier &pk) { pk_ = pk; }
+
+  [[nodiscard]] bool has_primary_key() const {
+    std::lock_guard lock(mutex_);
+    return !pk_.is_null();
+  }
+
+  [[nodiscard]] utils::identifier primary_key() const {
+    std::lock_guard lock(mutex_);
+    return pk_;
+  }
+
+  void primary_key(const utils::identifier &pk) {
+    std::lock_guard lock(mutex_);
+    pk_ = pk;
+  }
 
   bool is_persistent() const { return is_state(object_state::Persistent); }
   bool is_transient() const { return is_state(object_state::Transient); }
   bool is_detached() const { return is_state(object_state::Detached); }
   bool is_removed() const { return is_state(object_state::Removed); }
-  bool is_state(const object_state state) const { return state_ == state; }
+
+  bool is_state(const object_state state) const {
+    std::lock_guard lock(mutex_);
+    return state_ == state;
+  }
 
   void change_state(const object_state state) {
-    state_.store(state, std::memory_order_release);
-  }
-private:
-  Type* resolve() const {
-    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)");
+    state_ = state;
+  }
+private:
+  std::shared_ptr<Type> resolve_object() const {
+    std::shared_ptr<Type> current;
+    std::shared_ptr<object_resolver<Type>> resolver;
+    utils::identifier pk;
+
+    {
+      std::lock_guard lock(mutex_);
+      if (obj_) {
+        return obj_;
+      }
+
+      resolver = resolver_.lock();
+      if (!resolver) {
+        return nullptr;
+      }
+
+      pk = pk_;
     }
 
-    const_cast<std::shared_ptr<Type>&>(obj_) = resolver->resolve(pk_);
+    current = resolver->resolve(pk);
 
-    return obj_.get();
+    {
+      std::lock_guard lock(mutex_);
+      if (!obj_) {
+        obj_ = std::move(current);
+      }
+      return obj_;
+    }
   }
-
 private:
-  std::shared_ptr<Type> obj_{};
-  std::weak_ptr<object_resolver<Type>> resolver_{};
+  mutable std::shared_ptr<Type> obj_{};
+  mutable std::weak_ptr<object_resolver<Type>> resolver_{};
   utils::identifier pk_{};
-  std::atomic<object_state> state_{object_state::Transient};
+  object_state state_{object_state::Transient};
   mutable std::mutex mutex_{};
 };
 }

include/matador/object/object_ptr.hpp

@@ -17,68 +17,152 @@ inline constexpr null_object_ptr_t nullobj{};
 template <typename Type>
 class object_ptr {
 public:
-  object_ptr()
+object_ptr()
   : proxy_(std::make_shared<object_proxy<Type>>()) {}
+
   object_ptr(null_object_ptr_t) {}
+
   explicit object_ptr(std::shared_ptr<Type> obj)
-  : proxy_(std::make_shared<object_proxy<Type>>(obj)) {}
+  : proxy_(std::make_shared<object_proxy<Type>>(std::move(obj))) {}
+
   explicit object_ptr(std::shared_ptr<object_proxy<Type>> obj)
   : 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;
+  object_ptr& operator=(object_ptr &&other) noexcept = default;
+
   object_ptr& operator=(null_object_ptr_t) {
     proxy_.reset();
     return *this;
   }
 
   bool operator==(const object_ptr &other) const {
-    return get() == other.get();
+    if (proxy_ == other.proxy_) {
+      return true;
+    }
+
+    if (!proxy_ || !other.proxy_) {
+      return false;
+    }
+
+    if (has_primary_key() && other.has_primary_key()) {
+      return primary_key() == other.primary_key();
+    }
+
+    return false;
   }
+
   bool operator==(null_object_ptr_t) const {
     return empty();
   }
+
   bool operator!=(const object_ptr &other) const { return !operator==(other); }
   bool operator!=(null_object_ptr_t) const { return !empty(); }
 
   using value_type = Type;
 
-  Type *operator->() const { return get(); }
-  Type &operator*() { return *get(); }
-  const Type &operator*() const { return *get(); }
+  Type *operator->() const {
+    return checked_get();
+  }
 
-  [[nodiscard]] bool empty() const { return get() == nullptr; }
+  Type &operator*() {
+    return *checked_get();
+  }
+
+  const Type &operator*() const {
+    return *checked_get();
+  }
+
+  [[nodiscard]] bool empty() const {
+    return proxy_ == nullptr || proxy_->empty();
+  }
 
   Type *get() const {
     return proxy_ ? proxy_->pointer() : nullptr;
   }
 
-  void reset() { proxy_.reset(); }
-  void reset(const std::shared_ptr<object_proxy<Type>>& proxy) { proxy_ = proxy; }
+  [[nodiscard]] std::shared_ptr<Type> object() const {
+    return proxy_ ? proxy_->object() : nullptr;
+  }
 
-  [[nodiscard]] std::shared_ptr<object_proxy<Type>> proxy() const { return proxy_; }
+  void reset() {
+    proxy_.reset();
+  }
 
-  operator bool() const { return valid(); }
-  [[nodiscard]] bool valid() const { return proxy_ != nullptr && !proxy_->empty(); }
+  void reset(std::shared_ptr<object_proxy<Type>> proxy) {
+    proxy_ = std::move(proxy);
+  }
 
-  [[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]] std::shared_ptr<object_proxy<Type>> proxy() const {
+    return proxy_;
+  }
 
-  [[nodiscard]] bool is_persistent() const { return proxy_->is_persistent(); }
-  [[nodiscard]] bool is_transient() const { return proxy_->is_transient(); }
-  [[nodiscard]] bool is_detached() const { return proxy_->is_detached(); }
-  [[nodiscard]] bool is_removed() const { return proxy_->is_removed(); }
-  [[nodiscard]] bool is_state(const object_state state) const { return proxy_->is_state(state); }
+  explicit operator bool() const {
+    return valid();
+  }
+
+  [[nodiscard]] bool valid() const {
+    return proxy_ != nullptr && !proxy_->empty();
+  }
+
+  [[nodiscard]] bool has_primary_key() const {
+    return proxy_ != nullptr && proxy_->has_primary_key();
+  }
+
+  [[nodiscard]] utils::identifier primary_key() const {
+    return proxy_ ? proxy_->primary_key() : utils::identifier{};
+  }
+
+  void primary_key(const utils::identifier &pk) {
+    ensure_proxy();
+    proxy_->primary_key(pk);
+  }
+
+  [[nodiscard]] bool is_persistent() const {
+    return proxy_ != nullptr && proxy_->is_persistent();
+  }
+
+  [[nodiscard]] bool is_transient() const {
+    return proxy_ != nullptr && proxy_->is_transient();
+  }
+
+  [[nodiscard]] bool is_detached() const {
+    return proxy_ != nullptr && proxy_->is_detached();
+  }
+
+  [[nodiscard]] bool is_removed() const {
+    return proxy_ != nullptr && proxy_->is_removed();
+  }
+
+  [[nodiscard]] bool is_state(const object_state state) const {
+    return proxy_ != nullptr && proxy_->is_state(state);
+  }
 
   void change_state(object_state s) const {
     if (proxy_) {
       proxy_->change_state(s);
     }
   }
+
 private:
-  std::shared_ptr<object_proxy<Type> > proxy_{};
+  Type *checked_get() const {
+    auto *ptr = get();
+    if (!ptr) {
+      throw std::runtime_error("Cannot dereference empty object_ptr");
+    }
+    return ptr;
+  }
+
+  void ensure_proxy() {
+    if (!proxy_) {
+      proxy_ = std::make_shared<object_proxy<Type>>();
+    }
+  }
+
+private:
+  std::shared_ptr<object_proxy<Type>> proxy_{};
 };
 
 template<typename>

include/matador/object/relation_completer.hpp

@@ -172,7 +172,7 @@ void relation_completer<Type, Observers...>::on_has_many(const char *id, Collect
   using relation_value_type = many_to_many_relation<Type, value_type>;
 
   // Check if the object_ptr type is already inserted in the schema (by id)
-  auto foreign_node = find_node(typeid(value_type));
+  const auto foreign_node = find_node(typeid(value_type));
   if (!foreign_node) {
     // Todo: throw internal error or attach node
     return;
@@ -191,7 +191,7 @@ void relation_completer<Type, Observers...>::on_has_many(const char *id, Collect
       const auto local_endpoint = std::make_shared<relation_endpoint>(id, relation_type::HasMany, *foreign_node);
       nodes_.top()->info_->register_relation_endpoint(typeid(value_type), local_endpoint);
   } else {
-    // A relation table is necessary
+    // A relation table is necessary.
     // Endpoint was not found.
     // Always attach a many-to-many relation type. If later a
     // belongs-to relation handles this relation, the many-to-many
@@ -222,8 +222,7 @@ template<typename Type, template<typename> typename... Observers>
 template<class CollectionType>
 void relation_completer<Type, Observers...>::on_has_many(const char *id, CollectionType &, const char *join_column,
                                            const utils::foreign_attributes &,
-                                           std::enable_if_t<!is_object_ptr<typename CollectionType::value_type>::value>
-                                           * /*unused*/) {
+                                           std::enable_if_t<!is_object_ptr<typename CollectionType::value_type>::value>* /*unused*/) {
   using value_type = typename CollectionType::value_type;
   using relation_value_type = many_to_relation<Type, value_type>;
 
@@ -367,7 +366,12 @@ void relation_completer<Type, Observers...>::attach_relation_node(const std::str
 
   auto observers = internal::observer_list_copy_creator<Type, relation_value_type, Observers...>::copy_create(observers_);
 
-  auto node = repository_node::make_node<relation_value_type>(repo_, name, std::move(creator), std::move(observers));
+  auto node = repository_node::make_relation_node<relation_value_type>(repo_,
+                                                                       name,
+                                                                       join_column,
+                                                                       inverse_join_column,
+                                                                       std::move(creator),
+                                                                       std::move(observers));
   auto result = repo_.attach_node(node.release(), "");
   if (!result) {
     // Todo: throw internal error

include/matador/object/repository_node.hpp

@@ -23,6 +23,13 @@ public:
                                                     const std::string& name,
                                                     creator_func<Type> creator,
                                                     std::vector<std::unique_ptr<observer<Type>>>&& observers);
+  template < typename Type, template<typename> typename... Observers >
+  static std::unique_ptr<repository_node> make_relation_node(basic_repository& repo,
+                                                             const std::string& name,
+                                                             const std::string& join_column,
+                                                             const std::string& inverse_join_column,
+                                                             creator_func<Type> creator,
+                                                             std::vector<std::unique_ptr<observer<Type>>>&& observers);
 
   explicit repository_node(basic_repository& repo);
   repository_node(const repository_node& other) = delete;
@@ -101,5 +108,28 @@ std::unique_ptr<repository_node> repository_node::make_node(basic_repository &re
 
   return node;
 }
+
+template<typename Type, template <typename> class ... Observers>
+std::unique_ptr<repository_node> repository_node::make_relation_node(basic_repository &repo,
+                                                                     const std::string &name,
+                                                                     const std::string &join_column,
+                                                                     const std::string &inverse_join_column,
+                                                                     creator_func<Type> creator,
+                                                                     std::vector<std::unique_ptr<observer<Type>>> &&observers) {
+  const std::type_index ti(typeid(Type));
+  auto node = std::unique_ptr<repository_node>(new repository_node(repo, name, ti));
+
+  internal::observer_list_creator<Type, Observers...>::create_missing(observers);
+
+  auto obj = object_generator::generate<Type>(creator(), repo, name, join_column, inverse_join_column);
+  node->info_.reset(std::make_unique<object_info<Type>>(
+    *node,
+    obj,
+    std::move(observers),
+    std::forward<creator_func<Type>>(creator)
+  ).release());
+
+  return node;
+}
 }
 #endif //REPOSITORY_NODE_HPP

include/matador/object/restriction.hpp

@@ -17,17 +17,17 @@ class object;
 
 class restriction {
 public:
-  explicit restriction(const class attribute& attr);
+  explicit restriction(size_t attr_index);
 
-  [[nodiscard]] const class attribute& attribute() const;
+  [[nodiscard]] size_t attribute_index() const;
   [[nodiscard]] std::string column_name() const;
+  [[nodiscard]] utils::constraints options() const;
   [[nodiscard]] std::shared_ptr<object> owner() const;
   [[nodiscard]] bool is_primary_key_constraint() const;
   [[nodiscard]] bool is_foreign_key_constraint() const;
   [[nodiscard]] bool is_unique_constraint() const;
   [[nodiscard]] std::string ref_table_name() const;
   [[nodiscard]] std::string ref_column_name() const;
-
   friend std::ostream& operator<<(std::ostream& os, const restriction& c);
 
   [[nodiscard]] std::string type_string() const;
@@ -37,7 +37,7 @@ private:
   friend class object_generator;
   friend class object;
 
-  const class attribute& attr_;
+  const size_t index_;
   std::weak_ptr<object> owner_;
   std::weak_ptr<object> reference_;
   utils::constraints options_{utils::constraints::None};

include/matador/query/criteria/binary_criteria.hpp

@@ -8,12 +8,12 @@
 
 namespace matador::query {
 enum class binary_operator {
-    EQUALS,
-    NOT_EQUALS,
-    GREATER_THAN,
-    GREATER_THAN_OR_EQUAL,
-    LESS_THAN,
-    LESS_THAN_OR_EQUAL,
+    Equals,
+    NotEquals,
+    GreaterThan,
+    GreaterThanOrEqual,
+    LessThan,
+    LessThanOrEqual,
 };
 
 class binary_criteria final : public abstract_column_criteria {

include/matador/query/criteria/criteria_operators.hpp

@@ -20,33 +20,33 @@ class table_column;
 template<class Type>
 std::enable_if_t<!std::is_base_of_v<fetchable_query, std::decay_t<Type>>, criteria_ptr>
 operator==(const table_column &col, Type val) {
-    return std::make_unique<binary_criteria>(col, binary_operator::EQUALS, utils::value(val));
+    return std::make_unique<binary_criteria>(col, binary_operator::Equals, utils::value(val));
 }
 
 template<class Type>
 std::enable_if_t<!std::is_base_of_v<fetchable_query, std::decay_t<Type>>, criteria_ptr>
 operator!=(const table_column &col, Type val) {
-    return std::make_unique<binary_criteria>(col, binary_operator::NOT_EQUALS, utils::value(val));
+    return std::make_unique<binary_criteria>(col, binary_operator::NotEquals, utils::value(val));
 }
 
 template<class Type>
 criteria_ptr operator>(const table_column &col, Type val) {
-    return std::make_unique<binary_criteria>(col, binary_operator::GREATER_THAN, utils::value(val));
+    return std::make_unique<binary_criteria>(col, binary_operator::GreaterThan, utils::value(val));
 }
 
 template<class Type>
 criteria_ptr operator>=(const table_column &col, Type val) {
-    return std::make_unique<binary_criteria>(col, binary_operator::GREATER_THAN_OR_EQUAL, utils::value(val));
+    return std::make_unique<binary_criteria>(col, binary_operator::GreaterThanOrEqual, utils::value(val));
 }
 
 template<class Type>
 criteria_ptr operator<(const table_column &col, Type val) {
-    return std::make_unique<binary_criteria>(col, binary_operator::LESS_THAN, utils::value(val));
+    return std::make_unique<binary_criteria>(col, binary_operator::LessThan, utils::value(val));
 }
 
 template<class Type>
 criteria_ptr operator<=(const table_column &col, Type val) {
-    return std::make_unique<binary_criteria>(col, binary_operator::LESS_THAN_OR_EQUAL, utils::value(val));
+    return std::make_unique<binary_criteria>(col, binary_operator::LessThanOrEqual, utils::value(val));
 }
 
 criteria_ptr operator==(const table_column &col_left, const table_column &col_right);

include/matador/query/delete_query_builder.hpp

@@ -7,13 +7,11 @@
 
 #include "matador/query/basic_schema.hpp"
 #include "matador/query/error_code.hpp"
-#include "matador/query/execute_step.hpp"
+#include "matador/query/delete_step.hpp"
 #include "matador/query/query_contexts.hpp"
 #include "matador/query/query_builder_exception.hpp"
 #include "matador/query/query_builder_utils.hpp"
 
-#include "matador/sql/internal/identifier_statement_binder.hpp"
-#include "matador/sql/execute_result.hpp"
 #include "matador/sql/statement.hpp"
 
 #include "matador/utils/error.hpp"
@@ -22,61 +20,10 @@
 #include "matador/utils/result.hpp"
 
 namespace matador::query {
-template<typename ObjectType>
-class delete_step_object final : public execute_step {
-public:
-  delete_step_object(sql::query_context ctx, const object::object_ptr<ObjectType> &ptr)
-  : execute_step(std::move(ctx))
-  , ptr_(ptr) {}
-
-  utils::result<void, utils::error> prepare(sql::executor &/*conn*/) override {
-    id_ = ptr_.primary_key();
-    return utils::ok<void>();
-  }
-
-  utils::result<void, utils::error> execute(sql::statement &stmt) override {
-    if (!ptr_) {
-      return utils::failure(utils::error{error_code::InvalidObject, "Object is null"});
-    }
-
-    sql::identifier_statement_binder binder(stmt, 0);
-    binder.bind(id_);
-
-    if (const auto result = stmt.execute(); !result.is_ok()) {
-      return utils::failure(result.err());
-    }
-
-    return utils::ok<void>();
-  }
-
-  utils::result<void, utils::error> finalize(object::object_cache &cache, const resolver_service_ptr& /*resolver_service*/) override {
-    if (!ptr_) {
-      return utils::failure(utils::error{error_code::InvalidObject, "Object is null"});
-    }
-
-    cache.erase<ObjectType>(id_);
-    ptr_.change_state(object::object_state::Transient);
-
-    return utils::ok<void>();
-  }
-
-private:
-  object::object_ptr<ObjectType> ptr_;
-};
-
-struct delete_context {
-  const basic_schema &schema_;
-  const std::unordered_map<std::type_index, query_contexts> &contexts_by_type_;
-
-  std::vector<std::unique_ptr<execute_step>> steps_{};
-  std::vector<std::unique_ptr<execute_step>> relation_steps_{};
-  std::unordered_set<std::pair<std::type_index, const void *>, entity_visit_key_hash> visited_{};
-};
-
 template<typename ObjectType>
 class delete_step_processor {
 public:
-  explicit delete_step_processor(delete_context &ctx)
+  explicit delete_step_processor(query_builder_context &ctx)
   : ctx_(ctx) {}
 
   utils::result<void, utils::error> build(object::object_ptr<ObjectType> ptr, const bool as_relation_step = false) {
@@ -97,8 +44,7 @@ public:
       return utils::failure(utils::error{error_code::UnknownType, "Unknown type"});
     }
 
-    const auto &info = it->second.node().info();
-    if (!info.has_primary_key()) {
+    if (const auto &info = it->second.node().info(); !info.has_primary_key()) {
       return utils::failure(utils::error{error_code::MissingPrimaryKey, "Type " + info.name() + " has no primary key"});
     }
 
@@ -177,19 +123,50 @@ public:
   }
 
   template<class ForeignType>
-  void on_has_many_to_many(const char * /*id*/,
+  void on_has_many_to_many(const char *id,
                            object::collection<object::object_ptr<ForeignType>> &objects,
-                           const char * /*join_column*/,
-                           const char * /*inverse_join_column*/,
+                           const char *join_column,
+                           const char *inverse_join_column,
                            const utils::foreign_attributes &attr) {
-    on_many_to_many_objects(objects, attr);
+    if (id == nullptr || join_column == nullptr || inverse_join_column == nullptr) {
+      return;
+    }
+
+    using relation_value_type = object::many_to_many_relation<ObjectType, ForeignType>;
+    const std::type_index foreign_type{typeid(ForeignType)};
+    const std::type_index local_type{typeid(ObjectType)};
+    on_many_to_many_objects<relation_value_type>(
+      id,
+      objects,
+      attr,
+      [foreign_type, local_type](const char* relation_name) -> processing_many_to_many_key {
+        return {std::string{relation_name}, local_type, foreign_type};
+      });
   }
 
   template<class ForeignType>
-  void on_has_many_to_many(const char * /*id*/,
+  void on_has_many_to_many(const char *id,
                            object::collection<object::object_ptr<ForeignType>> &objects,
                            const utils::foreign_attributes &attr) {
-    on_many_to_many_objects(objects, attr);
+    if (id == nullptr) {
+      return;
+    }
+
+    object::join_columns_collector collector;
+    if (auto join_columns = collector.collect<ForeignType>(); join_columns.join_column.empty() || join_columns.inverse_join_column.empty()) {
+      return;
+    }
+
+    using relation_value_type = object::many_to_many_relation<ForeignType, ObjectType>;
+    const std::type_index foreign_type{typeid(ForeignType)};
+    const std::type_index local_type{typeid(ObjectType)};
+    on_many_to_many_objects<relation_value_type>(
+      id,
+      objects,
+      attr,
+      [foreign_type, local_type](const char* relation_name) -> processing_many_to_many_key {
+         return {std::string{relation_name}, foreign_type, local_type};
+      });
   }
 
 private:
@@ -207,28 +184,52 @@ private:
     }
   }
 
-  template<class ForeignType>
-  void on_many_to_many_objects(object::collection<object::object_ptr<ForeignType>> &objects,
-                               const utils::foreign_attributes &attr) {
+  template<class LocalType, class ForeignType, class RelationKeyFactory>
+  void on_many_to_many_objects(const char *id,
+                               object::collection<object::object_ptr<ForeignType>> &objects,
+                               const utils::foreign_attributes &attr,
+                               RelationKeyFactory make_relation_key) {
     if (!utils::is_cascade_type_set(attr.cascade(), utils::cascade_type::Remove)) {
       return;
     }
 
+    const auto key = make_relation_key(id);
+    if (ctx_.processing_many_to_many_relations_.find(key) != ctx_.processing_many_to_many_relations_.end()) {
+      return;
+    }
+
+    const auto it = ctx_.schema_.find(std::string{id});
+    if (it == ctx_.schema_.end()) {
+      throw query_builder_exception(error_code::UnknownType, "Unknown type for relation " + std::string{id});
+    }
+
+    if (std::type_index(typeid(LocalType)) != it->second.node().info().type_index()) {
+      throw query_builder_exception(error_code::InvalidRelationType, "Invalid relation type for " + std::string{id});
+    }
+
+    if (const auto cit = ctx_.contexts_by_type_.find(it->second.node().info().type_index()); cit == ctx_.contexts_by_type_.end()) {
+      throw query_builder_exception(error_code::UnknownType, "No query contexts for type " + it->second.node().name());
+    }
+
+    std::ignore = ctx_.processing_many_to_many_relations_.insert(key);
+    std::vector<std::unique_ptr<execute_step>> delete_relation_steps;
     delete_step_processor<ForeignType> processor{ctx_};
     for (auto &obj : objects) {
       if (!obj) {
         continue;
       }
 
-      auto result = processor.build(obj, true);
-      if (!result) {
-        throw query_builder_exception(result.release_error());
+      if (obj.is_persistent()) {
+        auto result = processor.build(obj, true);
+        if (!result) {
+          throw query_builder_exception(result.release_error());
+        }
       }
     }
   }
 
 private:
-  delete_context &ctx_;
+  query_builder_context &ctx_;
   object::object_ptr<ObjectType> ptr_;
 };
 
@@ -245,7 +246,7 @@ public:
       return utils::failure(utils::error{error_code::UnknownType, "Unknown type for delete query"});
     }
 
-    delete_context ctx{schema_, contexts_by_type_};
+    query_builder_context ctx{schema_, contexts_by_type_};
     delete_step_processor<ObjectType> processor{ctx};
 
     const auto result = processor.build(ptr);

include/matador/query/delete_step.hpp

@@ -0,0 +1,84 @@
+#ifndef MATADOR_DELETE_STEP_HPP
+#define MATADOR_DELETE_STEP_HPP
+
+#include "matador/query/error_code.hpp"
+#include "matador/query/execute_step.hpp"
+
+#include "matador/sql/internal/identifier_statement_binder.hpp"
+#include "matador/sql/statement.hpp"
+
+#include "matador/object/object_ptr.hpp"
+
+namespace matador::query {
+template<typename ObjectType>
+class delete_step_object final : public execute_step {
+public:
+  delete_step_object(sql::query_context ctx, const object::object_ptr<ObjectType> &ptr)
+  : execute_step(std::move(ctx))
+  , ptr_(ptr) {}
+
+  utils::result<void, utils::error> prepare(sql::executor &/*conn*/) override {
+    id_ = ptr_.primary_key();
+    return utils::ok<void>();
+  }
+
+  utils::result<void, utils::error> execute(sql::statement &stmt) override {
+    if (!ptr_) {
+      return utils::failure(utils::error{error_code::InvalidObject, "Object is null"});
+    }
+
+    sql::identifier_statement_binder binder(stmt, 0);
+    binder.bind(id_);
+
+    if (const auto result = stmt.execute(); !result.is_ok()) {
+      return utils::failure(result.err());
+    }
+
+    return utils::ok<void>();
+  }
+
+  utils::result<void, utils::error> finalize(object::object_cache &cache, const resolver_service_ptr& /*resolver_service*/) override {
+    if (!ptr_) {
+      return utils::failure(utils::error{error_code::InvalidObject, "Object is null"});
+    }
+
+    cache.erase<ObjectType>(id_);
+    ptr_.change_state(object::object_state::Transient);
+
+    return utils::ok<void>();
+  }
+
+private:
+  object::object_ptr<ObjectType> ptr_;
+};
+
+template <typename ObjectType>
+class delete_step_relation : public execute_step {
+public:
+  delete_step_relation(sql::query_context ctx, const object::object_ptr<ObjectType>& ptr)
+  : execute_step(std::move(ctx))
+  , ptr_(ptr) {}
+
+  utils::result<void, utils::error> prepare(sql::executor &) override {
+    return utils::ok<void>();
+  }
+  utils::result<void, utils::error> execute(sql::statement &stmt) override {
+    stmt.bind(*ptr_);
+    if (const auto exec_result = stmt.execute(); !exec_result.is_ok()) {
+      return utils::failure(exec_result.err());
+    }
+
+    return utils::ok<void>();
+  }
+
+  utils::result<void, utils::error> finalize(object::object_cache& /*cache*/, const resolver_service_ptr& /*resolver_service*/) override {
+    return utils::ok<void>();
+  }
+
+private:
+  object::object_ptr<ObjectType> ptr_;
+};
+
+}
+
+#endif //MATADOR_DELETE_STEP_HPP

include/matador/query/expression_evaluator.hpp

@@ -19,7 +19,7 @@ public:
     void visit(const value_expression& node) override;
     void visit(const placeholder_expression& node) override;
 
-    const std::string& result() const;
+    [[nodiscard]] const std::string& result() const;
 
 private:
     const sql::dialect &dialect_;

include/matador/query/insert_query_builder.hpp

@@ -56,49 +56,10 @@ private:
   std::string join_column_;
 };
 
-struct processing_many_to_many_key {
-  std::string id;
-  std::type_index local_type{typeid(void)};
-  std::type_index foreign_type{typeid(void)};
-  bool operator==(processing_many_to_many_key const &other) const {
-    return local_type == other.local_type && foreign_type == other.foreign_type && id == other.id;
-  }
-};
-
-template<class LocalType, typename ForeignType>
-static processing_many_to_many_key make_processing_many_to_many_key(const std::string &id) {
-  return {id, std::type_index(typeid(LocalType)), std::type_index(typeid(ForeignType))};
-}
-
-struct processing_many_to_many_key_hash {
-  size_t operator()(const processing_many_to_many_key &p) const noexcept {
-    size_t seed = std::hash<std::type_index>{}(p.local_type);
-
-    const size_t foreign_hash = std::hash<std::type_index>{}(p.foreign_type);
-    seed ^= foreign_hash + 0x9e3779b97f4a7c15ULL + (seed << 6) + (seed >> 2);
-
-    const size_t id_hash = std::hash<std::string>{}(p.id);
-    seed ^= id_hash + 0x9e3779b97f4a7c15ULL + (seed << 6) + (seed >> 2);
-
-    return seed;
-  }
-};
-
-struct insert_context {
-  const basic_schema &schema_;
-  const std::unordered_map<std::type_index, query_contexts> &contexts_by_type_;
-
-  std::vector<std::unique_ptr<execute_step>> steps_{};
-  std::vector<std::unique_ptr<execute_step>> relation_steps_{};
-  std::unordered_set<std::pair<std::type_index, const void *>, entity_visit_key_hash> visited_{};
-  std::unordered_set<processing_many_to_many_key, processing_many_to_many_key_hash> processing_many_to_many_relations_{};
-
-};
-
 template < typename ObjectType >
 class insert_step_processor {
 public:
-  explicit insert_step_processor(insert_context &ctx)
+  explicit insert_step_processor(query_builder_context &ctx)
   : ctx_{ctx}
   {}
 
@@ -247,7 +208,6 @@ public:
       attr,
       [foreign_type, local_type](const char* relation_name) -> processing_many_to_many_key {
         return {std::string{relation_name}, local_type, foreign_type};
-        // return make_processing_many_to_many_key<ObjectType, ForeignType>(relation_name);
       },
       [this, join_column, inverse_join_column](const auto &obj) {
         return object::make_object<relation_value_type>(join_column, inverse_join_column, ptr_, obj);
@@ -275,7 +235,6 @@ public:
       attr,
       [foreign_type, local_type](const char* relation_name) -> processing_many_to_many_key {
         return {std::string{relation_name}, foreign_type, local_type};
-        return make_processing_many_to_many_key<ForeignType, ObjectType>(relation_name);
       },
       [this, join_columns = std::move(join_columns)](const auto &obj) {
         return object::make_object<relation_value_type>(join_columns.inverse_join_column, join_columns.join_column, obj, ptr_);
@@ -297,12 +256,12 @@ private:
     }
   }
 
-    template<class LocalType, class ForeignType, class RelationKeyFactory, class RelationFactory>
-    void insert_many_to_many_relations(const char *id,
-                                       object::collection<object::object_ptr<ForeignType>> &objects,
-                                       const utils::foreign_attributes &attr,
-                                       RelationKeyFactory make_relation_key,
-                                       RelationFactory make_relation) {
+  template<class LocalType, class ForeignType, class RelationKeyFactory, class RelationFactory>
+  void insert_many_to_many_relations(const char *id,
+                                     object::collection<object::object_ptr<ForeignType>> &objects,
+                                     const utils::foreign_attributes &attr,
+                                     RelationKeyFactory make_relation_key,
+                                     RelationFactory make_relation) {
     if (!utils::is_cascade_type_set(attr.cascade(), utils::cascade_type::Insert)) {
       return;
     }
@@ -343,7 +302,7 @@ private:
 
       auto rel = make_relation(obj);
 
-      access::process(*this, *rel);
+      // access::process(*this, *rel);
 
       insert_relation_steps.push_back(std::make_unique<insert_step_relation<LocalType>>(cit->second.insert, rel));
     }
@@ -365,7 +324,7 @@ private:
   }
 
 private:
-  insert_context& ctx_;
+  query_builder_context& ctx_;
   object::object_ptr<ObjectType> ptr_;
 };
 
@@ -382,7 +341,7 @@ public:
       return utils::failure(utils::error{error_code::UnknownType, "Unknown type for insert query"});
     }
 
-    insert_context ctx{schema_, contexts_by_type_};
+    query_builder_context ctx{schema_, contexts_by_type_};
     insert_step_processor<ObjectType> processor{ctx};
 
     const auto result = processor.build(ptr);

include/matador/query/intermediates/query_create_intermediate.hpp

@@ -11,6 +11,8 @@
 #include "matador/object/attribute.hpp"
 #include "matador/object/restriction.hpp"
 
+#include <list>
+
 namespace matador::query {
 class table;
 class query_create_table_columns_intermediate : public executable_query {
@@ -28,7 +30,7 @@ public:
   using query_intermediate::query_intermediate;
 
   query_create_table_columns_intermediate columns(std::initializer_list<object::attribute> attributes);
-  query_create_table_columns_intermediate columns(const std::list<object::attribute> &attributes);
+  query_create_table_columns_intermediate columns(const std::vector<object::attribute> &attributes);
   query_create_table_columns_intermediate columns(std::initializer_list<table_column> columns);
   query_create_table_columns_intermediate columns(const std::list<table_column> &columns);
   query_create_table_columns_intermediate columns(const std::vector<table_column> &columns);

include/matador/query/meta_table_macro.hpp

@@ -18,7 +18,7 @@ TABLE_NAME##_table()\
 : TABLE_NAME##_table(#TABLE_NAME) \
 {} \
 TABLE_NAME##_table(const std::string& alias) \
-: typed_table(#TABLE_NAME, alias, {MAP(FIELD_STRING, __VA_ARGS__)}) \
+: typed_table(#TABLE_NAME, alias, {MAP(FIELD_STRING, __VA_ARGS__)}, {}, {}) \
 MAP(INIT_FIELD, __VA_ARGS__) \
 {} \
 MAP(FIELD, __VA_ARGS__) \

include/matador/query/query_builder_utils.hpp

@@ -18,5 +18,43 @@ struct entity_visit_key_hash {
     return h1 ^ (h2 + 0x9e3779b97f4a7c15ULL + (h1 << 6) + (h1 >> 2));
   }
 };
+
+struct processing_many_to_many_key {
+  std::string id;
+  std::type_index local_type{typeid(void)};
+  std::type_index foreign_type{typeid(void)};
+  bool operator==(processing_many_to_many_key const &other) const {
+    return local_type == other.local_type && foreign_type == other.foreign_type && id == other.id;
+  }
+};
+
+template<class LocalType, typename ForeignType>
+static processing_many_to_many_key make_processing_many_to_many_key(const std::string &id) {
+  return {id, std::type_index(typeid(LocalType)), std::type_index(typeid(ForeignType))};
+}
+
+struct processing_many_to_many_key_hash {
+  size_t operator()(const processing_many_to_many_key &p) const noexcept {
+    size_t seed = std::hash<std::type_index>{}(p.local_type);
+
+    const size_t foreign_hash = std::hash<std::type_index>{}(p.foreign_type);
+    seed ^= foreign_hash + 0x9e3779b97f4a7c15ULL + (seed << 6) + (seed >> 2);
+
+    const size_t id_hash = std::hash<std::string>{}(p.id);
+    seed ^= id_hash + 0x9e3779b97f4a7c15ULL + (seed << 6) + (seed >> 2);
+
+    return seed;
+  }
+};
+
+struct query_builder_context {
+  const basic_schema &schema_;
+  const std::unordered_map<std::type_index, query_contexts> &contexts_by_type_;
+
+  std::vector<std::unique_ptr<execute_step>> steps_{};
+  std::vector<std::unique_ptr<execute_step>> relation_steps_{};
+  std::unordered_set<std::pair<std::type_index, const void *>, entity_visit_key_hash> visited_{};
+  std::unordered_set<processing_many_to_many_key, processing_many_to_many_key_hash> processing_many_to_many_relations_{};
+};
 }
 #endif //MATADOR_QUERY_BUILDER_UTILS_HPP

include/matador/query/schema.hpp

@@ -318,6 +318,7 @@ public:
 
 private:
   iterator insert_table(const std::type_index& ti, const object::repository_node &node, utils::generator_type generator_type);
+  iterator insert_relation_table(const std::type_index& ti, const object::repository_node &node);
 
 private:
   template<typename Type>
@@ -352,10 +353,6 @@ utils::result<sql::query_context, utils::error> query_object_resolver_producer<T
 
 template<typename Type>
 utils::result<sql::query_context, utils::error> query_joined_object_resolver_producer<Type>::build_query(const sql::dialect &d) {
-  // producer_creator pc(repo_, typeid(Type));
-  // Type obj;
-  // access::process(pc, obj);
-
   select_query_builder qb(repo_);
   const auto *join_column = table_[collection_name()];
   const auto result = qb.build<Type>(*join_column == utils::_);
@@ -368,17 +365,18 @@ utils::result<sql::query_context, utils::error> query_joined_object_resolver_pro
 
 template <typename Type>
 void schema_observer<Type>::on_attach(const object::repository_node &node, const Type &/*prototype*/) const {
-  primary_key_generator_finder finder;
-  const auto generator_type = finder.find(node.info<Type>().get());
-
-  const auto it = schema_.insert_table(typeid(Type), node, generator_type);
-
-  if (!it->second.node().info().has_primary_key()) {
-    return;
+  const object::object_info<Type>& info = node.info<Type>().get();
+  if (info.has_primary_key()) {
+    primary_key_generator_finder finder;
+    const auto generator_type = finder.find(info);
+    const auto it = schema_.insert_table(typeid(Type), node, generator_type);
+    auto producer = std::make_unique<query_object_resolver_producer<Type>>(schema_, it->second.table(), it->second.node().info().primary_key_attribute()->name());
+    schema_.resolver_producers_[typeid(Type)] = std::move(producer);
+  } else {
+    const auto it = schema_.insert_relation_table(typeid(Type), node);
+    // auto producer = std::make_unique<query_object_resolver_producer<Type>>(schema_, it->second.table(), it->second.node().info().primary_key_attribute()->name());
+    // schema_.resolver_producers_[typeid(Type)] = std::move(producer);
   }
-
-  auto producer = std::make_unique<query_object_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/schema_utils.hpp

@@ -0,0 +1,13 @@
+#ifndef MATADOR_SCHEMA_UTILS_HPP
+#define MATADOR_SCHEMA_UTILS_HPP
+
+#include "matador/query/query_contexts.hpp"
+#include "matador/query/basic_schema.hpp"
+
+namespace matador::sql {
+class dialect;
+}
+namespace matador::query {
+query_contexts to_query_contexts(const schema_node &node, const sql::dialect &d);
+}
+#endif //MATADOR_SCHEMA_UTILS_HPP

include/matador/query/table.hpp

@@ -17,6 +17,7 @@ public:
   table(const char *name); // NOLINT(*-explicit-constructor)
   table(const std::string& name); // NOLINT(*-explicit-constructor)
   table(const std::string& name, const std::vector<table_column>& columns);
+  table(const std::string& name, const std::vector<table_column>& columns, const std::string& join_column, const std::string& inverse_join_column);
   table(const table& other);
   table& operator=(const table& other);
   table(table&& other) noexcept;
@@ -44,11 +45,11 @@ public:
   [[nodiscard]] bool has_primary_key() const;
 
   [[nodiscard]] const table_column* primary_key_column() const;
-  [[nodiscard]] const std::string& join_column_name() const;
-  [[nodiscard]] const std::string& inverse_join_column_name() const;
+  [[nodiscard]] const table_column* join_column() const;
+  [[nodiscard]] const table_column* inverse_join_column() const;
 
 protected:
-  table(std::string  name, std::string  alias, const std::vector<table_column>& columns);
+  table(std::string name, std::string  alias, const std::vector<table_column>& columns, const std::string& join_column, const std::string& inverse_join_column);
 
 private:
   friend table_column;
@@ -60,8 +61,8 @@ private:
   std::vector<table_column> columns_;
 
   int pk_column_index_{-1};
-  std::string join_column_name_;
-  std::string inverse_join_column_name_;
+  int join_column_index_{-1};
+  int inverse_join_column_index_{-1};
 };
 
 template<typename Type = table>

include/matador/sql/statement.hpp

@@ -3,11 +3,10 @@
 
 #include "matador/sql/abstract_sql_logger.hpp"
 #include "matador/sql/error_code.hpp"
+#include "matador/sql/execute_result.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"
 
@@ -172,7 +171,8 @@ template<class Type>
 utils::result<query_result<Type>, utils::error> statement::fetch() {
   std::cout << statement_proxy_->sql() << std::endl;
   statement_proxy_->statement_->query_.result_type = typeid(Type);
-  return statement_proxy_->fetch(*bindings_).and_then([this](std::unique_ptr<query_result_impl> &&value) {
+  return statement_proxy_->fetch(*bindings_)
+  .and_then([this](std::unique_ptr<query_result_impl> &&value) -> utils::result<query_result<Type>, utils::error> {
     auto resolver = statement_proxy_->statement_->query_.resolver->object_resolver<Type>();
     const auto prototype = value->prototype();
     return utils::ok(query_result<Type>(std::forward<decltype(value)>(value), resolver, [prototype] {

include/matador/utils/result.hpp

@@ -2,7 +2,6 @@
 #define QUERY_RESULT_HPP
 
 #include <variant>
-#include <optional>
 #include <functional>
 #include <type_traits>
 
@@ -21,6 +20,7 @@ template < typename ValueType >
 class ok {
 public:
   using value_type = ValueType;
+  constexpr ok() = default;
   explicit constexpr ok(const ValueType &value) : value_(value) {}
   explicit constexpr ok(ValueType &&value) : value_(std::move(value)) {}
 
@@ -49,21 +49,49 @@ public:
 
   constexpr ErrorType&& release() { return std::move(error_); }
   const ErrorType& value() const { return error_; }
-  ErrorType value() { return error_; }
+  ErrorType& value() { return error_; }
 
 private:
   ErrorType error_;
 };
 
+namespace detail {
+template <typename ValueType, typename Func, bool IsVoidValue = std::is_void_v<ValueType>>
+struct map_result_value_type;
+
+template <typename ValueType, typename Func>
+struct map_result_value_type<ValueType, Func, false> {
+  using type = std::invoke_result_t<Func, ValueType&&>;
+};
+
+template <typename ValueType, typename Func>
+struct map_result_value_type<ValueType, Func, true> {
+  using type = std::invoke_result_t<Func>;
+};
+
+template <typename ValueType, typename Func, bool IsVoidValue = std::is_void_v<ValueType>>
+struct and_then_result_type;
+
+template <typename ValueType, typename Func>
+struct and_then_result_type<ValueType, Func, false> {
+  using type = std::invoke_result_t<Func, ValueType&&>;
+};
+
+template <typename ValueType, typename Func>
+struct and_then_result_type<ValueType, Func, true> {
+  using type = std::invoke_result_t<Func>;
+};
+}
+
 template < typename ValueType, typename ErrorType >
 class result {
 public:
   using value_type = ValueType;
   using error_type = ErrorType;
 
-  result() : result_(ValueType{}) {}
-  result(ok<value_type> value) : result_(std::move(value.release())) {} // NOLINT(*-explicit-constructor)
-  result(failure<error_type> error) : result_(std::move(error.release())) {} // NOLINT(*-explicit-constructor)
+  result() : result_(ok<value_type>{}) {}
+  result(ok<value_type> value) : result_(std::move(value)) {} // NOLINT(*-explicit-constructor)
+  result(failure<error_type> error) : result_(std::move(error)) {} // NOLINT(*-explicit-constructor)
   result(const result &x) = default;
   result& operator=(const result &x) = default;
   result(result &&x) = default;
@@ -71,123 +99,128 @@ public:
 
   operator bool() const { return is_ok(); } // NOLINT(*-explicit-constructor)
 
-  [[nodiscard]] bool is_ok() const { return std::holds_alternative<value_type>(result_); }
-  [[nodiscard]] bool is_error() const { return std::holds_alternative<error_type>(result_); }
+  [[nodiscard]] bool is_ok() const {
+    return std::holds_alternative<ok<value_type>>(result_);
+  }
+  [[nodiscard]] bool is_error() const {
+    return std::holds_alternative<failure<error_type>>(result_);
+  }
 
-  ValueType&& release() { return std::move(std::get<value_type>(result_)); }
-  ErrorType&& release_error() { return std::move(std::get<error_type>(result_)); }
+  template <typename T = ValueType>
+  std::enable_if_t<!std::is_void_v<T>, T&&> release() {
+    return std::move(std::get<ok<value_type>>(result_).release());
+  }
+  ErrorType&& release_error() {
+    return std::move(std::get<failure<error_type>>(result_).release());
+  }
 
-  const ValueType& value() const { return std::get<value_type>(result_); }
-  ValueType& value() { return std::get<value_type>(result_); }
-  const ErrorType& err() const { return std::get<error_type>(result_); }
-  ErrorType err() { return std::get<error_type>(result_); }
+  template <typename T = ValueType>
+  std::enable_if_t<!std::is_void_v<T>, const T&> value() const {
+    return std::get<ok<value_type>>(result_).value();
+  }
+  template <typename T = ValueType>
+  std::enable_if_t<!std::is_void_v<T>, T&> value() {
+    return std::get<ok<value_type>>(result_).value();
+  }
+  const ErrorType& err() const {
+    return std::get<failure<error_type>>(result_).value();
+  }
+  ErrorType& err() {
+    return std::get<failure<error_type>>(result_).value();
+  }
 
-  constexpr const ValueType* operator->() const { return &value(); }
-  constexpr ValueType* operator->() { return &std::get<value_type>(result_); }
+  template <typename T = ValueType>
+  constexpr std::enable_if_t<!std::is_void_v<T>, const T*> operator->() const {
+    return &value();
+  }
+  template <typename T = ValueType>
+  constexpr std::enable_if_t<!std::is_void_v<T>, T*> operator->() {
+    return &value();
+  }
 
-  constexpr const ValueType& operator*() const& noexcept { return value(); }
-  constexpr ValueType& operator*() & noexcept { return value(); }
+  template <typename T = ValueType>
+  constexpr std::enable_if_t<!std::is_void_v<T>, const T&> operator*() const& noexcept {
+    return value();
+  }
+  template <typename T = ValueType>
+  constexpr std::enable_if_t<!std::is_void_v<T>, T&> operator*() & noexcept {
+    return value();
+  }
 
   template<typename Func,
-           typename SecondValueType = std::invoke_result_t<Func, ValueType >>
+           typename SecondValueType = typename detail::map_result_value_type<ValueType, Func>::type>
   result<SecondValueType, ErrorType> map(Func &&f) {
-    if (is_ok()) {
-      return result<SecondValueType, ErrorType>(ok(f(release())));
+    if (is_error()) {
+      return failure<ErrorType>(release_error());
     }
 
-    return result<SecondValueType, ErrorType>(failure(release_error()));
+    if constexpr (std::is_void_v<ValueType>) {
+      if constexpr (std::is_void_v<SecondValueType>) {
+        std::invoke(std::forward<Func>(f));
+        return ok<void>{};
+      } else {
+        return ok<SecondValueType>(std::invoke(std::forward<Func>(f)));
+      }
+    } else {
+      if constexpr (std::is_void_v<SecondValueType>) {
+        std::invoke(std::forward<Func>(f), release());
+        return ok<void>{};
+      } else {
+        return ok<SecondValueType>(std::invoke(std::forward<Func>(f), release()));
+      }
+    }
   }
 
   template<typename Func,
            typename SecondErrorType = typename std::invoke_result_t<Func, ErrorType >::value_type>
   result<SecondErrorType, ErrorType> map_error(Func &&f) {
-    if (!is_ok()) {
-      return result<SecondErrorType, ErrorType>(ok(release()));
+    if (!is_error()) {
+      return failure<SecondErrorType>{std::invoke(std::forward<Func>(f), release_error())};
     }
 
-    return result<SecondErrorType, ErrorType>(error(release_error()));
+    if constexpr (std::is_void_v<ValueType>) {
+      return ok<void>{};
+    } else {
+      return ok<ValueType>(release());
+    }
   }
 
-  template<typename Func,
-           typename SecondValueType = typename std::invoke_result_t<Func, ValueType>::value_type>
-  result<SecondValueType, ErrorType> and_then(Func &&f) {
+  template <typename Func,
+            typename ReturnResult = typename detail::and_then_result_type<ValueType, Func>::type>
+  ReturnResult and_then(Func &&f) {
+    static_assert(is_result<ReturnResult>::value, "and_then() callback must return matador::utils::result");
+
     if (is_ok()) {
-      return f(release());
+      if constexpr (std::is_void_v<ValueType>) {
+        return std::invoke(std::forward<Func>(f));
+      } else {
+        return std::invoke(std::forward<Func>(f), release());
+      }
     }
 
-    return result<SecondValueType, ErrorType>(failure(release_error()));
+    return ReturnResult(failure<ErrorType>(release_error()));
   }
 
-  template<typename Func,
-           typename SecondErrorType = typename std::invoke_result_t<Func, ErrorType&& >::value_type>
+  template <typename Func,
+            typename FailureType = std::invoke_result_t<Func, ErrorType&&>,
+            typename SecondErrorType = typename FailureType::value_type>
   result<ValueType, SecondErrorType> or_else(Func &&f) {
     if (is_error()) {
-      return f(release_error());
+      return result<ValueType, SecondErrorType>(
+        std::invoke(std::forward<Func>(f), release_error())
+      );
     }
 
-    return result<ValueType, SecondErrorType>(ok(release()));
+    if constexpr (std::is_void_v<ValueType>) {
+      return ok<void>{};
+    } else {
+      return ok<ValueType>(release());
+    }
   }
 
 private:
-  std::variant<value_type, error_type> result_;
+  std::variant<ok<value_type>, failure<error_type>> result_;
 };
-
-template < typename ErrorType >
-class result<void, ErrorType>
-{
-public:
-  using value_type = void;
-  using error_type = ErrorType;
-
-  result() = default;
-  result(ok<void> /*value*/) {}
-  result(failure<error_type> error) : result_(std::move(error.release())) {} // NOLINT(*-explicit-constructor)
-  result(const result &x) = default;
-  result& operator=(const result &x) = default;
-  result(result &&x) = default;
-  result& operator=(result &&x) = default;
-
-  operator bool() const { return is_ok(); } // NOLINT(*-explicit-constructor)
-
-  [[nodiscard]] bool is_ok() const { return !result_.has_value(); }
-  [[nodiscard]] bool is_error() const { return result_.has_value(); }
-
-  ErrorType&& release_error() { return std::move(*result_); }
-
-  const ErrorType& err() const { return result_.value(); }
-  ErrorType err() { return result_.value(); }
-
-  template<typename Func, typename SecondValueType = std::invoke_result_t<Func>>
-  result<SecondValueType, ErrorType> map(Func &&f) {
-    if (is_ok()) {
-      return result<SecondValueType, ErrorType>(ok(f()));
-    }
-
-    return result<SecondValueType, ErrorType>(failure(release_error()));
-  }
-
-  template<typename Func>
-  result and_then(Func &&f) {
-    if (is_ok()) {
-      return f();
-    }
-
-    return result(failure(release_error()));
-  }
-
-  template<typename Func, typename SecondErrorType = typename std::invoke_result_t<Func, ErrorType&& >::value_type>
-  result<void, SecondErrorType> or_else(Func &&f) {
-    if (is_error()) {
-      return f(release_error());
-    }
-
-    return result<void, SecondErrorType>(ok<void>());
-  }
-
-private:
-  std::optional<error_type> result_;
-};
-
 }
 
 #endif //QUERY_RESULT_HPP

include/matador/utils/value.hpp

@@ -56,7 +56,7 @@ public:
     if (!res.is_ok()) {
       return std::nullopt;
     }
-    return *res;
+    return res.value();
   }
 
   template<class Type>

include/matador/utils/version.hpp

@@ -3,16 +3,16 @@
 
 #include "matador/utils/result.hpp"
 #include "matador/utils/error.hpp"
+#include "matador/utils/export.hpp"
 
 #include <string>
-#include <ostream>
 
 namespace matador::utils {
 
-class version {
+class MATADOR_UTILS_API version final {
 public:
   version() = default;
-  ~version() =default;
+  ~version() = default;
   version(unsigned int major, unsigned int minor, unsigned int patch);
   version(const version& x) = default;
   version& operator=(const version& x) = default;

source/core/object/attribute.cpp

@@ -32,6 +32,10 @@ std::string attribute::full_name() const {
   return owner ? owner->name() + "." + name_ : name_;
 }
 
+size_t attribute::index() const {
+  return index_;
+}
+
 const utils::field_attributes &attribute::attributes() const {
   return options_;
 }

source/core/object/basic_object_info.cpp

@@ -21,11 +21,11 @@ std::shared_ptr<class object> basic_object_info::object() const {
   return object_;
 }
 
-const std::list<attribute>& basic_object_info::attributes() const {
+const std::vector<attribute>& basic_object_info::attributes() const {
   return object_->attributes();
 }
 
-const std::list<class restriction>& basic_object_info::constraints() const {
+const std::list<restriction>& basic_object_info::constraints() const {
   return object_->constraints();
 }
 
@@ -37,7 +37,7 @@ const utils::identifier& basic_object_info::primary_key() const {
   return object_->primary_key();
 }
 
-attribute* basic_object_info::primary_key_attribute() const {
+const attribute* basic_object_info::primary_key_attribute() const {
   return object_->primary_key_attribute();
 }
 

source/core/object/basic_repository.cpp

@@ -88,7 +88,7 @@ utils::result<basic_object_info_ref, utils::error> basic_repository::basic_info(
     return utils::ok(basic_object_info_ref{it->info()});
 }
 
-utils::result<attribute*, utils::error> basic_repository::primary_key_attribute(const std::type_index &ti) const {
+utils::result<const attribute*, utils::error> basic_repository::primary_key_attribute(const std::type_index &ti) const {
   const auto it = find_node(ti);
   if (it == end()) {
     return utils::failure(make_error(error_code::NodeNotFound, "Node '" + std::string(ti.name()) + "' not found."));

source/core/object/object.cpp

@@ -10,8 +10,8 @@ const attribute& object::create_attribute(std::string name, const std::shared_pt
   return obj->attributes_.emplace_back(std::move(attr));
 }
 
-attribute* object::primary_key_attribute() const {
-  return pk_attribute_;
+const attribute* object::primary_key_attribute() const {
+  return pk_column_index_ != -1 ? &attributes_.at(pk_column_index_) : nullptr;
 }
 
 const utils::identifier& object::primary_key() const {
@@ -19,7 +19,19 @@ const utils::identifier& object::primary_key() const {
 }
 
 bool object::has_primary_key() const {
-  return pk_attribute_ != nullptr;
+  return pk_column_index_ != -1;
+}
+
+bool object::is_relation_object() const {
+  return join_column_index_ != -1 && inverse_join_column_index_ != -1;
+}
+
+const attribute * object::join_attribute() const {
+  return join_column_index_ != -1 ? &attributes_.at(join_column_index_) : nullptr;
+}
+
+const attribute * object::inverse_join_attribute() const {
+  return inverse_join_column_index_ != -1 ? &attributes_.at(inverse_join_column_index_) : nullptr;
 }
 
 const std::string& object::name() const {
@@ -38,7 +50,7 @@ size_t object::attribute_count() const {
   return attributes_.size();
 }
 
-const std::list<attribute>& object::attributes() const {
+const std::vector<attribute>& object::attributes() const {
   return attributes_;
 }
 

source/core/object/object_generator.cpp

@@ -5,54 +5,69 @@
 #include <algorithm>
 
 namespace matador::object {
-object_generator::object_generator(basic_repository& repo, const std::shared_ptr<object>& object)
+object_generator::object_generator(basic_repository &repo, const std::shared_ptr<object> &object)
 : repo_(repo)
-, object_(object) {}
-
-std::shared_ptr<object> object_generator::acquire_object(basic_repository &repo, const std::type_index &ti, const std::string& name) {
-    if (repo.has_object_for_type(ti)) {
-        auto obj = repo.object_for_type(ti);
-        repo.remove_object_for_type(ti);
-        obj->update_name(name);
-        return obj;
-    }
-
-    return repo.provide_object_in_advance(ti, std::make_shared<object>(name));
+, object_(object) {
 }
 
-void object_generator::on_revision(const char* id, uint64_t& rev) {
-    access::attribute(*this, id, rev);
+std::shared_ptr<object> object_generator::acquire_object(basic_repository &repo, const std::type_index &ti, const std::string &name) {
+  if (repo.has_object_for_type(ti)) {
+    auto obj = repo.object_for_type(ti);
+    repo.remove_object_for_type(ti);
+    obj->update_name(name);
+    return obj;
+  }
+
+  return repo.provide_object_in_advance(ti, std::make_shared<object>(name));
 }
 
-void object_generator::create_pk_constraint(const std::string& name) const {
-    const auto pk_attr = find_attribute_by_name(name);
-    if (pk_attr == std::end(object_->attributes_)) {
-      return;
-    }
-    restriction pk_constraint(*pk_attr);
-    pk_constraint.options_ |= utils::constraints::PrimaryKey;
-    pk_constraint.owner_ = object_;
-    object_->constraints_.emplace_back(std::move(pk_constraint));
+void object_generator::on_revision(const char *id, uint64_t &rev) {
+  access::attribute(*this, id, rev);
 }
 
-void object_generator::create_unique_constraint(const std::string& name) const {
-    const auto pk_attr = find_attribute_by_name(name);
-    if (pk_attr == std::end(object_->attributes_)) {
-        return;
-    }
-    restriction pk_constraint(*pk_attr);
-    pk_constraint.options_ |= utils::constraints::Unique;
-    pk_constraint.owner_ = object_;
+void object_generator::create_pk_constraint(const std::string &name) const {
+  const auto pk_attr = find_attribute_by_name(name);
+  if (pk_attr == std::end(object_->attributes_)) {
+    return;
+  }
+  restriction pk_constraint(pk_attr->index());
+  pk_constraint.options_ |= utils::constraints::PrimaryKey;
+  pk_constraint.owner_ = object_;
+  object_->constraints_.emplace_back(std::move(pk_constraint));
 }
 
-std::list<attribute>::iterator object_generator::find_attribute_by_name(const std::string& name) const {
-    return std::find_if(std::begin(object_->attributes_), std::end(object_->attributes_), [&name](const attribute& elem) {
-      return elem.name() == name;
-    });
+void object_generator::create_unique_constraint(const std::string &name) const {
+  const auto pk_attr = find_attribute_by_name(name);
+  if (pk_attr == std::end(object_->attributes_)) {
+    return;
+  }
+  restriction pk_constraint(pk_attr->index());
+  pk_constraint.options_ |= utils::constraints::Unique;
+  pk_constraint.owner_ = object_;
 }
 
-void object_generator::prepare_primary_key(attribute& ref, utils::identifier &&pk) const {
-    object_->pk_attribute_ = &ref;
-    object_->pk_identifier_ = std::move(pk);
+std::vector<attribute>::iterator object_generator::find_attribute_by_name(const std::string &name) const {
+  return std::find_if(std::begin(object_->attributes_), std::end(object_->attributes_), [&name](const attribute &elem) {
+    return elem.name() == name;
+  });
+}
+
+void object_generator::prepare_primary_key(const attribute &ref, utils::identifier &&pk) const {
+  object_->pk_column_index_ = static_cast<int>(ref.index_);
+  object_->pk_identifier_ = std::move(pk);
+}
+
+void object_generator::prepare_relation_table(const std::string &join_column, const std::string &inverse_join_column) const {
+  auto it = find_attribute_by_name(join_column);
+  if (it == std::end(object_->attributes_)) {
+    return;
+  }
+  object_->join_column_index_ = static_cast<int>(it->index_);
+
+  it = find_attribute_by_name(inverse_join_column);
+  if (it == std::end(object_->attributes_)) {
+    return;
+  }
+  object_->inverse_join_column_index_ = static_cast<int>(it->index_);
 }
 }

source/core/object/restriction.cpp

@@ -4,16 +4,23 @@
 #include "matador/object/object.hpp"
 
 namespace matador::object {
-restriction::restriction(const class attribute& attr)
-: attr_(attr) {}
+restriction::restriction(const size_t attr_index)
+: index_(attr_index) {}
 
-const class attribute& restriction::attribute() const {
-  return attr_;
+size_t restriction::attribute_index() const {
+  return index_;
 }
 
 std::string restriction::column_name() const {
-  return attr_.name();
+  const auto o = owner_.lock();
+  return o ? o->attributes().at(index_).name() : "";
 }
+
+utils::constraints restriction::options() const {
+  const auto o = owner_.lock();
+  return o ? o->attributes().at(index_).attributes().options() : utils::constraints::None;
+}
+
 std::shared_ptr<object> restriction::owner() const {
   return owner_.lock();
 }

source/core/utils/version.cpp

@@ -3,98 +3,122 @@
 #include <matador/utils/errors.hpp>
 
 namespace matador::utils {
+namespace {
 
-version::version(unsigned int major, unsigned int minor, unsigned int patch)
-: major_(major)
-, minor_(minor)
-, patch_(patch)
-{}
+bool parse_uint_component(const std::string &text, std::size_t &pos, unsigned int &value) {
+  if (pos >= text.size() || text[pos] < '0' || text[pos] > '9') {
+    return false;
+  }
 
-bool version::operator==(const version &x) const
-{
-  return major_ == x.major_ &&
-         minor_ == x.minor_ &&
-         patch_ == x.patch_;
+  unsigned int result{};
+
+  while (pos < text.size() && text[pos] >= '0' && text[pos] <= '9') {
+    const auto digit = static_cast<unsigned int>(text[pos] - '0');
+
+    if (result > (std::numeric_limits<unsigned int>::max() - digit) / 10) {
+      return false;
+    }
+
+    result = result * 10 + digit;
+    ++pos;
+  }
+
+  value = result;
+  return true;
 }
 
-bool version::operator!=(const version &x) const
-{
+bool parse_dot(const std::string &text, std::size_t &pos) {
+  if (pos >= text.size() || text[pos] != '.') {
+    return false;
+  }
+
+  ++pos;
+  return true;
+}
+
+} // namespace
+version::version(const unsigned int major, const unsigned int minor, const unsigned int patch)
+: major_(major)
+, minor_(minor)
+, patch_(patch) {
+}
+
+bool version::operator==(const version& x) const {
+  return major_ == x.major_ &&
+    minor_ == x.minor_ &&
+    patch_ == x.patch_;
+}
+
+bool version::operator!=(const version& x) const {
   return !(*this == x);
 }
 
-bool version::operator>(const version &x) const
-{
+bool version::operator>(const version& x) const {
   return !(*this <= x);
 }
 
-bool version::operator>=(const version &x) const
-{
+bool version::operator>=(const version& x) const {
   return !(*this < x);
 }
 
-bool version::operator<(const version &x) const
-{
+bool version::operator<(const version& x) const {
   return (major_ < x.major_) ||
-         (major_ == x.major_ && minor_ < x.minor_) ||
-         (major_ == x.major_ && minor_ == x.minor_ && patch_ < x.patch_);
+    (major_ == x.major_ && minor_ < x.minor_) ||
+    (major_ == x.major_ && minor_ == x.minor_ && patch_ < x.patch_);
 }
 
-bool version::operator<=(const version &x) const
-{
+bool version::operator<=(const version& x) const {
   return *this < x || *this == x;
 }
 
-std::string version::str() const
-{
-  char buf[32];
-  sprintf(buf, "%d.%d.%d", major_, minor_, patch_);
-  return buf;
+std::string version::str() const {
+  return std::to_string(major_) + "." +
+    std::to_string(minor_) + "." +
+    std::to_string(patch_);
 }
 
-std::ostream &operator<<(std::ostream &out, const version &v)
-{
+std::ostream& operator<<(std::ostream& out, const version& v) {
   out << v.str();
   return out;
 }
 
-result<version, error> version::from_string(const std::string &version_string)
-{
-  version result;
-  if (const auto ret = sscanf(version_string.c_str(), "%u.%u.%u", &result.major_, &result.minor_, &result.patch_); ret != 3) {
+result<version, error> version::from_string(const std::string& version_string) {
+  unsigned int major{};
+  unsigned int minor{};
+  unsigned int patch{};
+
+  if (std::size_t pos{}; !parse_uint_component(version_string, pos, major) ||
+      !parse_dot(version_string, pos) ||
+      !parse_uint_component(version_string, pos, minor) ||
+      !parse_dot(version_string, pos) ||
+      !parse_uint_component(version_string, pos, patch) ||
+      pos != version_string.size()) {
     return failure(error(utils_error::InvalidVersionString, version_string));
-  }
+      }
 
-  return ok(result);
-}
+  return ok(version{major, minor, patch});}
 
-unsigned int version::major() const
-{
+unsigned int version::major() const {
   return major_;
 }
 
-unsigned int version::minor() const
-{
+unsigned int version::minor() const {
   return minor_;
 }
 
-unsigned int version::patch() const
-{
+unsigned int version::patch() const {
   return patch_;
 }
 
-void version::major(unsigned int m)
-{
+void version::major(unsigned int m) {
   major_ = m;
 }
 
-void version::minor(unsigned int m)
-{
+void version::minor(unsigned int m) {
   minor_ = m;
 }
 
-void version::patch(unsigned int p)
-{
+void version::patch(unsigned int p) {
   patch_ = p;
 }
-
-}
+}

source/orm/CMakeLists.txt

@@ -16,7 +16,10 @@ add_library(matador-orm STATIC
   ../../include/matador/query/criteria/logical_criteria.hpp
   ../../include/matador/query/criteria_evaluator.hpp
   ../../include/matador/query/database.hpp
+  ../../include/matador/query/delete_query_builder.hpp
+  ../../include/matador/query/delete_step.hpp
   ../../include/matador/query/error_code.hpp
+  ../../include/matador/query/execute_step.hpp
   ../../include/matador/query/expression/abstract_column_expression.hpp
   ../../include/matador/query/expression/binary_column_expression.hpp
   ../../include/matador/query/expression/column_expression.hpp
@@ -31,7 +34,7 @@ add_library(matador-orm STATIC
   ../../include/matador/query/identity_pk_generator.hpp
   ../../include/matador/query/insert_query_builder.hpp
   ../../include/matador/query/insert_query_builder.hpp
-  ../../include/matador/query/execute_step.hpp
+  ../../include/matador/query/insert_step.hpp
   ../../include/matador/query/intermediates/executable_query.hpp
   ../../include/matador/query/intermediates/fetchable_query.hpp
   ../../include/matador/query/intermediates/query_alter_intermediate.hpp
@@ -68,9 +71,9 @@ add_library(matador-orm STATIC
   ../../include/matador/query/key_value_generator.hpp
   ../../include/matador/query/manual_pk_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_builder_utils.hpp
   ../../include/matador/query/query_collection_resolver.hpp
   ../../include/matador/query/query_column.hpp
   ../../include/matador/query/query_contexts.hpp
@@ -80,6 +83,7 @@ add_library(matador-orm STATIC
   ../../include/matador/query/query_part.hpp
   ../../include/matador/query/query_utils.hpp
   ../../include/matador/query/schema.hpp
+  ../../include/matador/query/schema_utils.hpp
   ../../include/matador/query/select_query_builder.hpp
   ../../include/matador/query/sequence_pk_generator.hpp
   ../../include/matador/query/session.hpp
@@ -104,9 +108,9 @@ 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/joined_collection_resolver_producer.hpp
   ../../include/matador/sql/internal/identifier_reader.hpp
   ../../include/matador/sql/internal/identifier_statement_binder.hpp
+  ../../include/matador/sql/internal/joined_collection_resolver_producer.hpp
   ../../include/matador/sql/internal/object_resolver_producer.hpp
   ../../include/matador/sql/internal/object_result_binder.hpp
   ../../include/matador/sql/internal/pk_reader.hpp
@@ -188,6 +192,7 @@ add_library(matador-orm STATIC
   query/query_part.cpp
   query/query_utils.cpp
   query/schema.cpp
+  query/schema_utils.cpp
   query/select_query_builder.cpp
   query/sequence_pk_generator.cpp
   query/session.cpp
@@ -208,9 +213,9 @@ add_library(matador-orm STATIC
   sql/interface/query_result_reader.cpp
   sql/interface/statement_impl.cpp
   sql/interface/statement_proxy.cpp
-  sql/internal/joined_collection_resolver_producer.cpp
   sql/internal/identifier_reader.cpp
   sql/internal/identifier_statement_binder.cpp
+  sql/internal/joined_collection_resolver_producer.cpp
   sql/internal/object_resolver_producer.cpp
   sql/internal/object_result_binder.cpp
   sql/internal/query_result_pk_resolver.cpp
@@ -221,9 +226,6 @@ add_library(matador-orm STATIC
   sql/resolver_service.cpp
   sql/statement.cpp
   sql/statement_cache.cpp
-  ../../include/matador/query/delete_query_builder.hpp
-  ../../include/matador/query/query_builder_utils.hpp
-  ../../include/matador/query/insert_step.hpp
 )
 
 target_include_directories(matador-orm

source/orm/query/criteria/criteria_operators.cpp

@@ -13,61 +13,61 @@ 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));
+  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));
+  return std::make_unique<binary_criteria>(col, binary_operator::NotEquals, conv.convert(id));
 }
 
 criteria_ptr operator==(const table_column &col, utils::placeholder p) {
-  return std::make_unique<binary_criteria>(col, binary_operator::EQUALS, p);
+  return std::make_unique<binary_criteria>(col, binary_operator::Equals, p);
 }
 
 criteria_ptr operator!=(const table_column &col, utils::placeholder p) {
-  return std::make_unique<binary_criteria>(col, binary_operator::NOT_EQUALS, p);
+  return std::make_unique<binary_criteria>(col, binary_operator::NotEquals, p);
 }
 
 criteria_ptr operator>(const table_column &col, utils::placeholder p) {
-  return std::make_unique<binary_criteria>(col, binary_operator::GREATER_THAN, p);
+  return std::make_unique<binary_criteria>(col, binary_operator::GreaterThan, p);
 }
 
 criteria_ptr operator>=(const table_column &col, utils::placeholder p) {
-  return std::make_unique<binary_criteria>(col, binary_operator::GREATER_THAN_OR_EQUAL, p);
+  return std::make_unique<binary_criteria>(col, binary_operator::GreaterThanOrEqual, p);
 }
 
 criteria_ptr operator<(const table_column &col, utils::placeholder p) {
-  return std::make_unique<binary_criteria>(col, binary_operator::LESS_THAN, p);
+  return std::make_unique<binary_criteria>(col, binary_operator::LessThan, p);
 }
 
 criteria_ptr operator<=(const table_column &col, utils::placeholder p) {
-  return std::make_unique<binary_criteria>(col, binary_operator::LESS_THAN_OR_EQUAL, p);
+  return std::make_unique<binary_criteria>(col, binary_operator::LessThanOrEqual, p);
 }
 
 criteria_ptr operator==( const table_column& col_left, const table_column& col_right ) {
-    return std::make_unique<binary_column_criteria>(col_left, binary_operator::EQUALS, col_right);
+    return std::make_unique<binary_column_criteria>(col_left, binary_operator::Equals, col_right);
 }
 
 criteria_ptr operator!=( const table_column& col_left, const table_column& col_right ) {
-    return std::make_unique<binary_column_criteria>(col_left, binary_operator::NOT_EQUALS, col_right);
+    return std::make_unique<binary_column_criteria>(col_left, binary_operator::NotEquals, col_right);
 }
 
 criteria_ptr operator>( const table_column& col_left, const table_column& col_right ) {
-    return std::make_unique<binary_column_criteria>(col_left, binary_operator::GREATER_THAN, col_right);
+    return std::make_unique<binary_column_criteria>(col_left, binary_operator::GreaterThan, col_right);
 }
 
 criteria_ptr operator>=( const table_column& col_left, const table_column& col_right ) {
-    return std::make_unique<binary_column_criteria>(col_left, binary_operator::GREATER_THAN_OR_EQUAL, col_right);
+    return std::make_unique<binary_column_criteria>(col_left, binary_operator::GreaterThanOrEqual, col_right);
 }
 
 criteria_ptr operator<( const table_column& col_left, const table_column& col_right ) {
-    return std::make_unique<binary_column_criteria>(col_left, binary_operator::LESS_THAN, col_right);
+    return std::make_unique<binary_column_criteria>(col_left, binary_operator::LessThan, col_right);
 }
 
 criteria_ptr operator<=( const table_column& col_left, const table_column& col_right ) {
-    return std::make_unique<binary_column_criteria>(col_left, binary_operator::LESS_THAN_OR_EQUAL, col_right);
+    return std::make_unique<binary_column_criteria>(col_left, binary_operator::LessThanOrEqual, col_right);
 }
 
 criteria_ptr operator&&(criteria_ptr left, criteria_ptr right) {

source/orm/query/criteria_evaluator.cpp

@@ -18,12 +18,12 @@
 namespace matador::query {
 namespace detail {
 static const utils::enum_mapper<binary_operator> BinaryOperatorEnum({
-  {binary_operator::EQUALS, "="},
-  {binary_operator::NOT_EQUALS, "<>"},
-  {binary_operator::GREATER_THAN, ">"},
-  {binary_operator::GREATER_THAN_OR_EQUAL, ">="},
-  {binary_operator::LESS_THAN, "<"},
-  {binary_operator::LESS_THAN_OR_EQUAL, "<="},
+  {binary_operator::Equals, "="},
+  {binary_operator::NotEquals, "<>"},
+  {binary_operator::GreaterThan, ">"},
+  {binary_operator::GreaterThanOrEqual, ">="},
+  {binary_operator::LessThan, "<"},
+  {binary_operator::LessThanOrEqual, "<="},
 });
 }
 

source/orm/query/intermediates/fetchable_query.cpp

@@ -30,7 +30,7 @@ utils::result<sql::query_result<sql::record>, utils::error> fetchable_query::fet
   auto ctx = compiler.build(*context_, exec.dialect(), std::nullopt);
   ctx.resolver = exec.resolver();
   return exec.fetch(ctx)
-    .and_then([](auto &&res) {
+    .and_then([](auto &&res) -> utils::result<sql::query_result<sql::record>, utils::error> {
       const auto prototype = res->prototype();
       return utils::ok(sql::query_result<sql::record>(std::forward<decltype(res)>(res), prototype));
     });

source/orm/query/intermediates/query_alter_table_intermediate.cpp

@@ -33,7 +33,7 @@ query_add_foreign_key_constraint_intermediate query_add_key_constraint_intermedi
 
 executable_query query_alter_table_intermediate::add_constraint(const object::restriction &rest) {
   context_->parts.push_back(std::make_unique<internal::query_add_constraint_part_by_constraint>(
-    table_constraint{rest.column_name(), rest.owner()->name(), rest.attribute().attributes().options(), rest.ref_table_name(), rest.ref_column_name()}
+    table_constraint{rest.column_name(), rest.owner()->name(), rest.options(), rest.ref_table_name(), rest.ref_column_name()}
   ));
 
   return {context_};
@@ -47,7 +47,7 @@ query_add_key_constraint_intermediate query_alter_table_intermediate::add_constr
 
 executable_query query_alter_table_intermediate::drop_constraint(const object::restriction &rest) {
   context_->parts.push_back(std::make_unique<internal::query_drop_key_constraint_part_by_constraint>(
-    table_constraint{rest.column_name(), rest.owner()->name(), rest.attribute().attributes().options(), rest.ref_table_name(), rest.ref_column_name()})
+    table_constraint{rest.column_name(), rest.owner()->name(), rest.options(), rest.ref_table_name(), rest.ref_column_name()})
   );
   return {context_};
 }

source/orm/query/intermediates/query_create_intermediate.cpp

@@ -46,11 +46,11 @@ executable_query query_create_table_columns_intermediate::constraints(const std:
   std::list<table_constraint> constraints;
   for (const auto& restr : restrictions) {
     if (restr.is_primary_key_constraint()) {
-      constraints.emplace_back(restr.column_name(), restr.owner()->name(), restr.attribute().attributes().options());
+      constraints.emplace_back(restr.column_name(), restr.owner()->name(), restr.options());
     } else if (restr.is_foreign_key_constraint()) {
-      constraints.emplace_back(restr.column_name(), restr.owner()->name(), restr.attribute().attributes().options(), restr.ref_table_name(), restr.ref_column_name());
+      constraints.emplace_back(restr.column_name(), restr.owner()->name(), restr.options(), restr.ref_table_name(), restr.ref_column_name());
     } else if (restr.is_unique_constraint()) {
-      constraints.emplace_back(restr.column_name(), restr.owner()->name(), restr.attribute().attributes().options());
+      constraints.emplace_back(restr.column_name(), restr.owner()->name(), restr.options());
     }
   }
   context_->parts.push_back(std::make_unique<internal::query_create_table_constraints_part>(constraints));
@@ -58,10 +58,10 @@ executable_query query_create_table_columns_intermediate::constraints(const std:
 }
 
 query_create_table_columns_intermediate query_create_table_intermediate::columns(const std::initializer_list<object::attribute> attributes) {
-  return columns(std::list(attributes));
+  return columns(std::vector(attributes));
 }
 
-query_create_table_columns_intermediate query_create_table_intermediate::columns(const std::list<object::attribute>& attributes) {
+query_create_table_columns_intermediate query_create_table_intermediate::columns(const std::vector<object::attribute>& attributes) {
   std::list<table_column> columns;
   for (const auto& attr : attributes) {
     auto options = attr.attributes().options();

source/orm/query/schema.cpp

@@ -59,4 +59,19 @@ schema::iterator schema::insert_table(const std::type_index &ti, const object::r
   }
   return schema_nodes_.insert({ti, schema_node{table(node.name(), columns), std::move(pk_generator), node}}).first;
 }
+
+basic_schema::iterator schema::insert_relation_table(const std::type_index &ti, const object::repository_node &node) {
+  std::vector<table_column> columns;
+  const auto* attr = node.info().object()->join_attribute();
+  if (attr == nullptr) {
+    return schema_nodes_.end();
+  }
+  columns.emplace_back(nullptr, attr->name(), attr->type(), attr->attributes());
+  attr = node.info().object()->inverse_join_attribute();
+  if (attr == nullptr) {
+    return schema_nodes_.end();
+  }
+  columns.emplace_back(nullptr, attr->name(), attr->type(), attr->attributes());
+  return schema_nodes_.insert({ti, schema_node{table(node.name(), columns, node.info().object()->join_attribute()->name(), node.info().object()->inverse_join_attribute()->name()), nullptr, node}}).first;
+}
 } // namespace matador::query

source/orm/query/schema_utils.cpp

@@ -0,0 +1,62 @@
+#include "matador/query/schema_utils.hpp"
+#include "matador/query/query.hpp"
+#include "matador/query/criteria.hpp"
+
+using namespace matador::utils;
+
+namespace matador::query {
+query_contexts to_query_contexts(const schema_node& node, const sql::dialect &d) {
+  query_contexts queries;
+
+  // SELECT all
+  queries.select_all = select(node.table())
+    .from(node.name())
+    .compile(d);
+  if (node.table().has_primary_key()) {
+    // SELECT one
+    queries.select_one = select(node.table())
+      .from(node.name())
+      .where(*node.table().primary_key_column() == _)
+      .compile(d);
+    // UPDATE one
+    auto update_set = query::update(node.table());
+    for (const auto &col: node.table().columns()) {
+      update_set.set(col, _);
+    }
+    queries.update_one = update_set.where(*node.table().primary_key_column() == _)
+      .compile(d);
+    // DELETE one
+    queries.delete_one = query::remove()
+      .from(node.name())
+      .where(*node.table().primary_key_column() == _)
+      .compile(d);
+  } else {
+    queries.delete_one = query::remove()
+      .from(node.name())
+      .where(*node.table().join_column() == _ && *node.table().inverse_join_column() == _)
+      .compile(d);
+  }
+  // INSERT one
+  std::vector<table_column> columns;
+  for (const auto &col: node.table().columns()) {
+    if (col.is_primary_key() && utils::is_constraint_set(col.attributes().options(), constraints::Identity)) {
+      continue;
+    }
+    columns.push_back(col);
+  }
+  if (node.table().has_primary_key() && node.pk_generator().type() == generator_type::Identity) {
+    queries.insert = query::insert()
+      .into(node.name(), columns)
+      .values(generator::placeholders(columns.size()))
+      .returning(node.table().primary_key_column()->as(node.table().primary_key_column()->column_name()))
+      .compile(d);
+  } else {
+    queries.insert = query::insert()
+      .into(node.name(), columns)
+      .values(generator::placeholders(columns.size()))
+      .compile(d);
+  }
+
+  return queries;
+}
+}

source/orm/query/select_query_builder.cpp

@@ -83,7 +83,7 @@ void select_query_builder::append_join(const table_column &left, const table_col
   using namespace matador::query;
   entity_query_data_.joins.push_back({
     right.table(),
-    std::make_unique<binary_column_criteria>(left, binary_operator::EQUALS, right)
+    std::make_unique<binary_column_criteria>(left, binary_operator::Equals, right)
   });
 }
 }

source/orm/query/session.cpp

@@ -3,9 +3,8 @@
 #include "matador/sql/backend_provider.hpp"
 #include "matador/sql/dialect.hpp"
 
-#include "matador/query/query.hpp"
-#include "matador/query/generator.hpp"
 #include "matador/query/basic_schema.hpp"
+#include "matador/query/schema_utils.hpp"
 
 #include <stdexcept>
 
@@ -23,51 +22,7 @@ session::session(session_context&& ctx, const basic_schema &scm)
 , resolver_service_(ctx.resolver_service) {
   using namespace matador::utils;
   for (const auto &[type, node] : schema_) {
-    query_contexts queries;
-
-    // SELECT all
-    queries.select_all = select(node.table())
-      .from(node.name())
-      .compile(dialect_);
-    if (node.table().has_primary_key()) {
-      // SELECT one
-      queries.select_one = select(node.table())
-        .from(node.name())
-        .where(*node.table().primary_key_column() == _)
-        .compile(dialect_);
-      // UPDATE one
-      auto update_set = query::update(node.table());
-      for (const auto &col: node.table().columns()) {
-        update_set.set(col, _);
-      }
-      queries.update_one = update_set.where(*node.table().primary_key_column() == _)
-        .compile(dialect_);
-      // DELETE one
-      queries.delete_one = query::remove()
-        .from(node.name())
-        .where(*node.table().primary_key_column() == _)
-        .compile(dialect_);
-    }
-    // INSERT one
-    std::vector<table_column> columns;
-    for (const auto &col: node.table().columns()) {
-      if (col.is_primary_key() && utils::is_constraint_set(col.attributes().options(), constraints::Identity)) {
-        continue;
-      }
-      columns.push_back(col);
-    }
-    if (node.pk_generator().type() == utils::generator_type::Identity) {
-      queries.insert = query::insert()
-        .into(node.name(), columns)
-        .values(generator::placeholders(columns.size()))
-        .returning(node.table().primary_key_column()->as(node.table().primary_key_column()->column_name()))
-        .compile(dialect_);
-    } else {
-      queries.insert = query::insert()
-        .into(node.name(), columns)
-        .values(generator::placeholders(columns.size()))
-        .compile(dialect_);
-    }
+    query_contexts queries = to_query_contexts(node, dialect_);
 
     queries.insert.resolver = resolver_service_;
     queries.update_one.resolver = resolver_service_;

source/orm/query/table.cpp

@@ -9,13 +9,17 @@ table::table(const char* name)
 {}
 
 table::table(const std::string& name)
-: table(name, name, {}) {}
+: table(name, name, {}, {}, {}) {}
 
 table::table(const std::string& name, const std::vector<table_column> &columns)
-: table(name, name, columns) {
+: table(name, name, columns, {}, {}) {
 }
 
-table::table(std::string name, std::string alias, const std::vector<table_column> &columns)
+table::table(const std::string& name, const std::vector<table_column>& columns, const std::string& join_column, const std::string& inverse_join_column)
+: table(name, name, columns, join_column, inverse_join_column) {
+}
+
+table::table(std::string name, std::string alias, const std::vector<table_column> &columns, const std::string& join_column, const std::string& inverse_join_column)
 : name_(std::move(name))
 , alias_(std::move(alias))
 , columns_(columns) {
@@ -24,6 +28,12 @@ table::table(std::string name, std::string alias, const std::vector<table_column
     if (columns_[i].is_primary_key()) {
       pk_column_index_ = i;
     }
+    if (columns_[i].column_name() == join_column) {
+      join_column_index_ = i;
+    }
+    if (columns_[i].column_name() == inverse_join_column) {
+      inverse_join_column_index_ = i;
+    }
   }
 }
 
@@ -32,7 +42,9 @@ table::table(const table &other)
 , alias_(other.alias_)
 , schema_name_(other.schema_name_)
 , columns_(other.columns_)
-, pk_column_index_(other.pk_column_index_){
+, pk_column_index_(other.pk_column_index_)
+, join_column_index_(other.join_column_index_)
+, inverse_join_column_index_(other.inverse_join_column_index_) {
   for (auto &col : columns_) {
     col.table(this);
   }
@@ -54,6 +66,8 @@ table & table::operator=(table &&other) noexcept {
   alias_ = std::move(other.alias_);
   columns_ = std::move(other.columns_);
   pk_column_index_ = other.pk_column_index_;
+  join_column_index_ = other.join_column_index_;
+  inverse_join_column_index_ = other.inverse_join_column_index_;
   for (auto &col : columns_) {
     col.table(this);
   }
@@ -65,7 +79,7 @@ bool table::operator==(const table& x) const {
 }
 
 table table::as(const std::string &alias) const {
-  return { name_, alias, columns_ };
+  return { name_, alias, columns_, join_column_index_ > -1 ? join_column()->name() : std::string{}, inverse_join_column_index_ > -1 ? inverse_join_column()->name() : std::string{}};
 }
 
 const std::string & table::table_name() const {
@@ -121,11 +135,11 @@ const table_column* table::primary_key_column() const {
   return pk_column_index_ > -1 ? &columns_.at(pk_column_index_) : nullptr;
 }
 
-const std::string &table::join_column_name() const {
-  return join_column_name_;
+const table_column* table::join_column() const {
+  return join_column_index_ > -1 ? &columns_.at(join_column_index_) : nullptr;
 }
 
-const std::string &table::inverse_join_column_name() const {
-  return inverse_join_column_name_;
+const table_column* table::inverse_join_column() const {
+  return inverse_join_column_index_ > -1 ? &columns_.at(inverse_join_column_index_) : nullptr;
 }
 }

test/backends/QueryFixture.cpp

@@ -37,7 +37,8 @@ void QueryFixture::check_table_not_exists(const std::string &table_name) const {
 }
 
 void QueryFixture::drop_table_if_exists(const std::string &table_name) const {
-  const auto result = db.exists(table_name).and_then([&table_name, this](const bool exists) {
+  const auto result = db.exists(table_name)
+  .and_then([&table_name, this](const bool exists) -> utils::result<bool, utils::error> {
     if (exists) {
       auto res = query::drop()
         .table(table_name)

test/backends/SequenceFixture.cpp

@@ -35,7 +35,8 @@ void SequenceFixture::check_sequence_not_exists(const std::string& sequence_name
 }
 
 void SequenceFixture::drop_sequence_if_exists(const std::string& sequence_name) const {
-  const auto result = db.sequence_exists(sequence_name).and_then([&sequence_name, this](const bool exists) {
+  const auto result = db.sequence_exists(sequence_name).
+  and_then([&sequence_name, this](const bool exists) -> utils::result<bool, utils::error> {
     if (exists) {
       auto res = query::drop()
         .sequence(sequence_name)

test/core/CMakeLists.txt

@@ -5,6 +5,7 @@ list(APPEND CMAKE_MODULE_PATH ${catch2_SOURCE_DIR}/extras)
 add_executable(CoreTests
   ../backends/SchemaFixture.hpp
   logger/LoggerTest.cpp
+  object/CollectionTest.cpp
   object/ObjectCacheTest.cpp
   object/ObjectTest.cpp
   object/PrimaryKeyResolverTest.cpp

test/core/object/CollectionTest.cpp

@@ -0,0 +1,16 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "matador/object/collection.hpp"
+#include "matador/object/object.hpp"
+
+#include <iostream>
+
+using namespace matador::object;
+
+TEST_CASE("Test collection", "[collection]") {
+    collection<int> ints{{1,2,3,4}};
+
+    for (auto const& i : ints) {
+        std::cout << i << std::endl ;
+    }
+}

test/core/object/ObjectCacheTest.cpp

@@ -59,7 +59,7 @@ private:
 };
 } // namespace
 
-TEST_CASE("object_cache: acquire_proxy returns the same proxy instance across threads", "[object][cache][threadsafe]") {
+TEST_CASE("ObjectCache: acquire_proxy returns the same proxy instance across threads", "[object][cache][threadsafe]") {
   matador::utils::message_bus bus;
   matador::object::object_cache cache(bus);
   const matador::utils::identifier id{123};
@@ -91,7 +91,7 @@ TEST_CASE("object_cache: acquire_proxy returns the same proxy instance across th
   }
 }
 
-TEST_CASE("object_cache: attach_entity makes is_loaded/get_entity reflect presence", "[object][cache]") {
+TEST_CASE("ObjectCache: attach_entity makes is_loaded/get_entity reflect presence", "[object][cache]") {
   matador::utils::message_bus bus;
   matador::object::object_cache cache(bus);
   const matador::utils::identifier id{42};
@@ -110,7 +110,7 @@ TEST_CASE("object_cache: attach_entity makes is_loaded/get_entity reflect presen
   REQUIRE(got->name == "hans");
 }
 
-TEST_CASE("object_cache: erase invalidates existing proxies", "[object][cache]") {
+TEST_CASE("ObjectCache: erase invalidates existing proxies", "[object][cache]") {
   matador::utils::message_bus bus;
   matador::object::object_cache cache(bus);
   const matador::utils::identifier id{9};

test/core/object/ObjectTest.cpp

@@ -7,7 +7,7 @@
 #include "../test/models/author.hpp"
 #include "../test/models/book.hpp"
 
-TEST_CASE("Generate object from type", "[object][generate]") {
+TEST_CASE("Object: Generate object from type", "[object][generate]") {
   using namespace matador;
   object::repository repo;
   auto result = repo.attach<test::author>("authors");

test/core/utils/IdentifierTest.cpp

@@ -6,7 +6,7 @@
 
 using namespace matador::utils;
 
-TEST_CASE("Test create identifier", "[identifier][create]") {
+TEST_CASE("Identifier: Test create identifier", "[identifier][create]") {
   const identifier id;
 
   REQUIRE(id.is_null());
@@ -16,7 +16,7 @@ TEST_CASE("Test create identifier", "[identifier][create]") {
   REQUIRE(id.str() == "null");
 }
 
-TEST_CASE("Test assign value to identifier", "[identifier][assign]") {
+TEST_CASE("Identifier: Test assign value to identifier", "[identifier][assign]") {
   identifier id;
 
   REQUIRE(id.is_null());
@@ -48,7 +48,7 @@ TEST_CASE("Test assign value to identifier", "[identifier][assign]") {
   // REQUIRE(id == identifier{"UniqueId"});
 }
 
-TEST_CASE("Test compare identifier", "[identifier][compare]") {
+TEST_CASE("Identifier: Test compare identifier", "[identifier][compare]") {
   identifier id1{6}, id2{7};
 
   REQUIRE(id1 != id2);
@@ -68,7 +68,7 @@ identifier create(const int id) {
   return identifier{id};
 }
 
-TEST_CASE("Test copy identifier" "[identifier][copy]") {
+TEST_CASE("Identifier: Test copy identifier" "[identifier][copy]") {
   identifier id1{"Unique"};
   REQUIRE(id1.is_valid());
   REQUIRE(id1.str() == "Unique");
@@ -92,7 +92,7 @@ TEST_CASE("Test copy identifier" "[identifier][copy]") {
   id3 = id1;
 }
 
-TEST_CASE("Test move identifier", "[identifier][move]") {
+TEST_CASE("Identifier: Test move identifier", "[identifier][move]") {
   identifier id1{6};
 
   REQUIRE(id1.is_integer());
@@ -103,7 +103,7 @@ TEST_CASE("Test move identifier", "[identifier][move]") {
   REQUIRE(id2.is_integer());
 }
 
-TEST_CASE("identifier assignment from integer types", "[utils][identifier][assign]") {
+TEST_CASE("Identifier: Identifier assignment from integer types", "[utils][identifier][assign]") {
   identifier id;
 
   id = int8_t{-5};
@@ -125,7 +125,7 @@ TEST_CASE("identifier assignment from integer types", "[utils][identifier][assig
   REQUIRE(id.is_valid());
 }
 
-TEST_CASE("identifier assignment from string type", "[utils][identifier][assign]") {
+TEST_CASE("Identifier: Identifier assignment from string type", "[utils][identifier][assign]") {
   identifier id;
 
   id = std::string{"hello"};
@@ -140,7 +140,7 @@ TEST_CASE("identifier assignment from string type", "[utils][identifier][assign]
   REQUIRE_FALSE(id.is_valid());
 }
 
-TEST_CASE("identifier assignment from const char*", "[utils][identifier][assign]") {
+TEST_CASE("Identifier: Identifier assignment from const char*", "[utils][identifier][assign]") {
   identifier id;
 
   id = "world";
@@ -155,7 +155,7 @@ TEST_CASE("identifier assignment from const char*", "[utils][identifier][assign]
   REQUIRE_FALSE(id.is_valid());
 }
 
-TEST_CASE("identifier assignment from nullptr", "[utils][identifier][assign]") {
+TEST_CASE("Identifier: Identifier assignment from nullptr", "[utils][identifier][assign]") {
   identifier id{42};
 
   REQUIRE(id.is_valid());
@@ -168,7 +168,7 @@ TEST_CASE("identifier assignment from nullptr", "[utils][identifier][assign]") {
   REQUIRE_FALSE(id.is_valid());
 }
 
-TEST_CASE("identifier reassignment between types", "[utils][identifier][assign]") {
+TEST_CASE("Identifier: Identifier reassignment between types", "[utils][identifier][assign]") {
   identifier id{uint64_t{7}};
 
   REQUIRE(id.is_integer());
@@ -189,7 +189,7 @@ TEST_CASE("identifier reassignment between types", "[utils][identifier][assign]"
   REQUIRE(id.str() == "null");
 }
 
-TEST_CASE("identifier as() returns exact integer type", "[utils][identifier][as]") {
+TEST_CASE("Identifier: Identifier as() returns exact integer type", "[utils][identifier][as]") {
   identifier id{int32_t{42}};
 
   const auto as_i32 = id.as<int32_t>();
@@ -200,7 +200,7 @@ TEST_CASE("identifier as() returns exact integer type", "[utils][identifier][as]
   REQUIRE(as_i64.is_error());
 }
 
-TEST_CASE("identifier as() returns exact string type", "[utils][identifier][as]") {
+TEST_CASE("Identifier: Identifier as() returns exact string type", "[utils][identifier][as]") {
   identifier id{std::string{"hello"}};
 
   const auto as_string = id.as<std::string>();
@@ -211,7 +211,7 @@ TEST_CASE("identifier as() returns exact string type", "[utils][identifier][as]"
   REQUIRE(as_i32.is_error());
 }
 
-TEST_CASE("identifier as() returns null type failure for null identifier", "[utils][identifier][as]") {
+TEST_CASE("Identifier: Identifier as() returns null type failure for null identifier", "[utils][identifier][as]") {
   identifier id{nullptr};
 
   const auto as_i32 = id.as<int32_t>();
@@ -221,7 +221,7 @@ TEST_CASE("identifier as() returns null type failure for null identifier", "[uti
   REQUIRE(as_string.is_error());
 }
 
-TEST_CASE("identifier convert() converts between integer types", "[utils][identifier][convert]") {
+TEST_CASE("Identifier: Identifier convert() converts between integer types", "[utils][identifier][convert]") {
   identifier id{int32_t{123}};
 
   const auto as_i64 = id.convert<int64_t>();
@@ -233,21 +233,21 @@ TEST_CASE("identifier convert() converts between integer types", "[utils][identi
   REQUIRE(*as_u8 == 123);
 }
 
-TEST_CASE("identifier convert() rejects out of range integer conversion", "[utils][identifier][convert]") {
+TEST_CASE("Identifier: Identifier convert() rejects out of range integer conversion", "[utils][identifier][convert]") {
   identifier id{int32_t{300}};
 
   const auto as_u8 = id.convert<uint8_t>();
   REQUIRE(as_u8.is_error());
 }
 
-TEST_CASE("identifier convert() rejects negative to unsigned conversion", "[utils][identifier][convert]") {
+TEST_CASE("Identifier: Identifier convert() rejects negative to unsigned conversion", "[utils][identifier][convert]") {
   identifier id{int32_t{-1}};
 
   const auto as_u32 = id.convert<uint32_t>();
   REQUIRE(as_u32.is_error());
 }
 
-TEST_CASE("identifier convert() rejects non-integer source types", "[utils][identifier][convert]") {
+TEST_CASE("Identifier: Identifier convert() rejects non-integer source types", "[utils][identifier][convert]") {
   identifier id{std::string{"123"}};
 
   const auto as_i32 = id.convert<int32_t>();
@@ -258,7 +258,7 @@ TEST_CASE("identifier convert() rejects non-integer source types", "[utils][iden
   REQUIRE(null_to_i64.is_error());
 }
 
-TEST_CASE("identifier convert() works with unsigned integer sources", "[utils][identifier][convert]") {
+TEST_CASE("Identifier: Identifier convert() works with unsigned integer sources", "[utils][identifier][convert]") {
   identifier id{uint16_t{500}};
 
   const auto as_i32 = id.convert<int32_t>();
@@ -269,7 +269,7 @@ TEST_CASE("identifier convert() works with unsigned integer sources", "[utils][i
   REQUIRE(as_u8.is_error());
 }
 
-TEST_CASE("identifier as() and convert() behave consistently for same integer type", "[utils][identifier][as][convert]") {
+TEST_CASE("Identifier: Identifier as() and convert() behave consistently", "[utils][identifier][as][convert]") {
   identifier id{uint64_t{77}};
 
   const auto as_u64 = id.as<uint64_t>();
@@ -281,7 +281,7 @@ TEST_CASE("identifier as() and convert() behave consistently for same integer ty
   REQUIRE(*conv_u64 == 77);
 }
 
-TEST_CASE("identifier assign from value", "[utils][identifier][assign]") {
+TEST_CASE("Identifier: Identifier assign from value", "[utils][identifier][assign]") {
   identifier id;
 
   value v1{int32_t{17}};
@@ -301,7 +301,7 @@ TEST_CASE("identifier assign from value", "[utils][identifier][assign]") {
   REQUIRE(r3.is_error());
 }
 
-TEST_CASE("identifier assign from value with exact type mapping", "[utils][identifier][assign]") {
+TEST_CASE("Identifier: Identifier assign from value with exact type mapping", "[utils][identifier][assign]") {
   identifier id;
 
   SECTION("integer types") {
@@ -328,7 +328,7 @@ TEST_CASE("identifier assign from value with exact type mapping", "[utils][ident
   }
 }
 
-TEST_CASE("identifier::to_database_type converts internal value to database_type", "[identifier]") {
+TEST_CASE("Identifier: Identifier::to_database_type converts internal value", "[identifier][to_database_type]") {
   SECTION("null identifier becomes nullptr") {
     identifier id{nullptr};
 
@@ -337,7 +337,7 @@ TEST_CASE("identifier::to_database_type converts internal value to database_type
     REQUIRE(std::holds_alternative<std::nullptr_t>(db_value));
   }
 
-  SECTION("signed integral identifier becomes same signed database type") {
+  SECTION("Identifier: Signed integral identifier becomes same signed database type") {
     identifier id{int32_t{42}};
 
     const auto db_value = id.to_database_type();
@@ -346,7 +346,7 @@ TEST_CASE("identifier::to_database_type converts internal value to database_type
     REQUIRE(std::get<int32_t>(db_value) == 42);
   }
 
-  SECTION("unsigned integral identifier becomes same unsigned database type") {
+  SECTION("Identifier: Unsigned integral identifier becomes same unsigned database type") {
     identifier id{uint64_t{123456789ULL}};
 
     const auto db_value = id.to_database_type();
@@ -355,7 +355,7 @@ TEST_CASE("identifier::to_database_type converts internal value to database_type
     REQUIRE(std::get<uint64_t>(db_value) == 123456789ULL);
   }
 
-  SECTION("string identifier becomes std::string database type") {
+  SECTION("Identifier: String identifier becomes std::string database type") {
     identifier id{std::string{"customer_1"}};
 
     const auto db_value = id.to_database_type();

test/core/utils/MessageBusTest.cpp

@@ -18,7 +18,7 @@ public:
 
 using namespace matador::utils;
 
-TEST_CASE("Basic publish/subscribe works", "[MessageBus]") {
+TEST_CASE("MessageBus: Basic publish/subscribe works", "[MessageBus]") {
     message_bus bus;
     int counter = 0;
 
@@ -32,7 +32,7 @@ TEST_CASE("Basic publish/subscribe works", "[MessageBus]") {
     REQUIRE(counter == 3);
 }
 
-TEST_CASE("Filtering works", "[MessageBus]") {
+TEST_CASE("MessageBus: Filtering works", "[MessageBus]") {
     message_bus bus;
     int counter = 0;
 
@@ -49,7 +49,7 @@ TEST_CASE("Filtering works", "[MessageBus]") {
     REQUIRE(counter == 6); // only 2 + 4
 }
 
-TEST_CASE("Member function subscription works", "[MessageBus]") {
+TEST_CASE("MessageBus: Member function subscription works", "[MessageBus]") {
     message_bus bus;
     Receiver r;
 
@@ -62,7 +62,7 @@ TEST_CASE("Member function subscription works", "[MessageBus]") {
     REQUIRE(r.received[1] == "world");
 }
 
-TEST_CASE("Shared_ptr instance subscription works", "[MessageBus]") {
+TEST_CASE("MessageBus: SharedPtr instance subscription works", "[MessageBus]") {
     message_bus bus;
     const auto r = std::make_shared<Receiver>();
 
@@ -73,7 +73,7 @@ TEST_CASE("Shared_ptr instance subscription works", "[MessageBus]") {
     REQUIRE(r->received[0] == "foo");
 }
 
-TEST_CASE("RAII unsubscription works", "[MessageBus]") {
+TEST_CASE("MessageBus: RAII unsubscription works", "[MessageBus]") {
     message_bus bus;
     int counter = 0;
 
@@ -90,7 +90,7 @@ TEST_CASE("RAII unsubscription works", "[MessageBus]") {
     REQUIRE(counter == 5);
 }
 
-TEST_CASE("Type-erased AnyMessage publish works", "[MessageBus]") {
+TEST_CASE("MessageBus: Type-erased AnyMessage publish works", "[MessageBus]") {
     message_bus bus;
     int counter = 0;
 
@@ -104,7 +104,7 @@ TEST_CASE("Type-erased AnyMessage publish works", "[MessageBus]") {
     REQUIRE(counter == 10);
 }
 
-TEST_CASE("Multiple subscribers all receive messages", "[MessageBus]") {
+TEST_CASE("MessageBus: Multiple subscribers all receive messages", "[MessageBus]") {
     message_bus bus;
     int a = 0, b = 0;
 
@@ -116,7 +116,7 @@ TEST_CASE("Multiple subscribers all receive messages", "[MessageBus]") {
     REQUIRE(b == 3);
 }
 
-TEST_CASE("Stress test with multi-threaded publish and subscribe", "[MessageBus][stress]") {
+TEST_CASE("MessageBus: Stress test with multi-threaded publish and subscribe", "[MessageBus][stress]") {
     message_bus bus;
     std::atomic<int> counter{0};
     constexpr int numThreads = 8;

test/core/utils/ResultTest.cpp

@@ -5,13 +5,15 @@
 #include "matador/utils/result.hpp"
 
 namespace matador::test {
+namespace {
 enum class math_error : int32_t {
   OK = 0,
   DIVISION_BY_ZERO = 1,
   FAILURE = 2
 };
+}
 
-utils::result<float, math_error>divide(const float x, const float y) {
+static utils::result<float, math_error>divide(const float x, const float y) {
   if (y == 0) {
     return utils::failure(math_error::DIVISION_BY_ZERO);
   }
@@ -19,15 +21,15 @@ utils::result<float, math_error>divide(const float x, const float y) {
   return utils::ok(x / y);
 }
 
-utils::result<float, math_error>multiply(const float x, const float y) {
+static utils::result<float, math_error>multiply(const float x, const float y) {
   return utils::ok(x * y);
 }
 
-utils::result<float, math_error>plus(const float x, const float y) {
+static utils::result<float, math_error>plus(const float x, const float y) {
   return utils::ok(x + y);
 }
 
-utils::result<void, math_error>action_on_greater_42(const float i) {
+static utils::result<void, math_error>action_on_greater_42(const float i) {
   if (i > 42) {
     return utils::ok<void>();
   }
@@ -88,7 +90,7 @@ TEST_CASE("Test result", "[result]") {
   REQUIRE(!res2.is_ok());
   REQUIRE(res2.is_error());
   const auto e = res2.err();
-//  REQUIRE(res2.err() == "division by zero error");
+  REQUIRE(res2.err() == "division by zero error");
 
   res = test::divide(4, 2)
     .and_then([](const auto &val) { return test::multiply(val, 5); })

test/core/utils/ThreadPoolTest.cpp

@@ -4,21 +4,21 @@
 
 using namespace matador::utils;
 
-TEST_CASE("thread_pool creates and rejects zero-sized construction") {
+TEST_CASE("ThreadPool: thread_pool creates and rejects zero-sized construction") {
     REQUIRE_THROWS(thread_pool(0));
 
     const thread_pool tp(2);
     REQUIRE(tp.size() == 2);
 }
 
-TEST_CASE("thread_pool schedules and runs simple tasks") {
+TEST_CASE("ThreadPool: thread_pool schedules and runs simple tasks") {
     thread_pool pool(3);
     auto fut = pool.schedule([](cancel_token&, const int x) { return x * 10; }, 7);
     REQUIRE(fut);
     REQUIRE(fut.value().get() == 70);
 }
 
-TEST_CASE("thread_pool parallel computation and results") {
+TEST_CASE("ThreadPool: thread_pool parallel computation and results") {
     thread_pool pool(4);
     std::vector<std::future<int>> futs;
     for (int i = 1; i <= 20; ++i) {
@@ -33,7 +33,7 @@ TEST_CASE("thread_pool parallel computation and results") {
     REQUIRE(sum == 230); // (2+3+...+21) = (21*22/2)-(1) = 231-1
 }
 
-TEST_CASE("thread_pool rejects scheduling after shutdown") {
+TEST_CASE("ThreadPool: thread_pool rejects scheduling after shutdown") {
     thread_pool pool(2);
     pool.shutdown();
     auto result = pool.schedule([](cancel_token&) { return 1; });
@@ -41,7 +41,7 @@ TEST_CASE("thread_pool rejects scheduling after shutdown") {
     REQUIRE(result.err().find("shut down") != std::string::npos);
 }
 
-TEST_CASE("thread_pool supports cancel_token for not-yet-run task") {
+TEST_CASE("ThreadPool: thread_pool supports cancel_token for not-yet-run task") {
     thread_pool pool(1);
     std::atomic ran{false};
 
@@ -73,7 +73,7 @@ TEST_CASE("thread_pool supports cancel_token for not-yet-run task") {
     // If started before cancel, may be 100 (rare but possible)
 }
 
-TEST_CASE("thread_pool: shutdown finishes all running tasks") {
+TEST_CASE("ThreadPool: thread_pool: shutdown finishes all running tasks") {
     thread_pool pool(2);
     std::atomic counter{0};
     std::vector<std::future<void>> futs;

test/core/utils/VersionTest.cpp

@@ -4,7 +4,26 @@
 
 using namespace matador::utils;
 
-TEST_CASE("Test version interface", "[version][interface]") {
+TEST_CASE("Version: Test form string", "[version][from_string]") {
+  REQUIRE(version::from_string("1.2.3").is_ok());
+  REQUIRE(version::from_string("0.0.0").is_ok());
+
+  REQUIRE(version::from_string("1.2").is_error());
+  REQUIRE(version::from_string("1.2.3.4").is_error());
+  REQUIRE(version::from_string("1.2.3abc").is_error());
+  REQUIRE(version::from_string("abc").is_error());
+  REQUIRE(version::from_string("-1.2.3").is_error());
+}
+
+TEST_CASE("Version: Test comparison", "[version][comparison]") {
+  REQUIRE(version(1, 2, 3) == version(1, 2, 3));
+  REQUIRE(version(1, 2, 3) < version(1, 2, 4));
+  REQUIRE(version(1, 2, 3) < version(1, 3, 0));
+  REQUIRE(version(1, 2, 3) < version(2, 0, 0));
+  REQUIRE(version(2, 0, 0) > version(1, 9, 9));
+}
+
+TEST_CASE("Version: Test interface", "[version][interface]") {
   version v0;
 
   REQUIRE(v0.major() == 0);
@@ -38,8 +57,8 @@ TEST_CASE("Test version interface", "[version][interface]") {
   REQUIRE(v2 == v1);
 }
 
-TEST_CASE("Test version parsing", "[version][parse]") {
-  const auto version_str{"13.67.34"};
+TEST_CASE("Version: Test parsing", "[version][parse]") {
+  constexpr auto version_str{"13.67.34"};
   const auto v1 = version::from_string(version_str);
   REQUIRE(v1.is_ok());
 

test/orm/CMakeLists.txt

@@ -3,6 +3,8 @@ CPMAddPackage("gh:catchorg/Catch2@3.14.0")
 list(APPEND CMAKE_MODULE_PATH ${catch2_SOURCE_DIR}/extras)
 
 add_executable(OrmTests
+  ../utils/RecordingObserver.cpp
+  ../utils/RecordingObserver.hpp
   backend/test_backend_service.cpp
   backend/test_backend_service.hpp
   backend/test_connection.cpp
@@ -16,6 +18,7 @@ add_executable(OrmTests
   query/ColumnExpressionTest.cpp
   query/ColumnGeneratorTest.cpp
   query/CriteriaTests.cpp
+  query/DeleteQueryBuilderTest.cpp
   query/GeneratorTests.cpp
   query/InsertQueryBuilderTest.cpp
   query/QueryBuilderTest.cpp
@@ -32,8 +35,6 @@ add_executable(OrmTests
   sql/StatementCacheTest.cpp
   utils/auto_reset_event.cpp
   utils/auto_reset_event.hpp
-  ../utils/RecordingObserver.hpp
-  ../utils/RecordingObserver.cpp
 )
 
 target_link_libraries(OrmTests matador-orm matador-core Catch2::Catch2WithMain)

test/orm/query/DeleteQueryBuilderTest.cpp

@@ -0,0 +1,108 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "matador/object/object_ptr.hpp"
+
+#include "matador/sql/backend_provider.hpp"
+#include "matador/sql/connection.hpp"
+#include "matador/sql/interface/connection_impl.hpp"
+
+#include "matador/query/schema.hpp"
+
+#include "matador/query/delete_query_builder.hpp"
+
+#include "QueryFixture.hpp"
+
+#include "../../models/author.hpp"
+#include "../../models/book.hpp"
+#include "../../models/airplane.hpp"
+#include "../../models/flight.hpp"
+#include "../../models/recipe.hpp"
+
+using namespace matador::object;
+using namespace matador::sql;
+using namespace matador::query;
+using namespace matador::utils;
+using namespace matador::test;
+
+TEST_CASE_METHOD(QueryFixture, "delete query builder test", "[query][delete_query_builder]") {
+  schema scm;
+  auto result = scm.attach<airplane>("airplanes")
+    .and_then( [&scm] { return scm.attach<flight>("flights"); } );
+  REQUIRE(result);
+
+  const auto contexts_by_type = to_contexts_by_name(scm, db->dialect());
+  delete_query_builder<airplane> dqb(scm, contexts_by_type);
+
+  const auto a380 = make_object<airplane>(1, "Boeing", "A380"  );
+  auto build_result = dqb.build(a380);
+  REQUIRE(build_result.is_ok());
+
+  const auto& stmts = *build_result;
+  REQUIRE(stmts.size() == 1);
+}
+
+TEST_CASE_METHOD(QueryFixture, "Test delete builder has many", "[query][delete_query_builder][has_many]") {
+  schema scm;
+  const auto result = scm.attach<book>("books")
+    .and_then( [&scm] { return scm.attach<author>("authors"); } );
+  REQUIRE(result.is_ok());
+
+  auto s_king = make_object<author>(1, "Steven", "King", "21.9.1947", 1956, false);
+
+  s_king->books.push_back(make_object<book>(2, "Carrie", object_ptr<author>{}, 1974));
+  s_king->books.push_back(make_object<book>(3, "The Shining", object_ptr<author>{}, 1977));
+  s_king->books.push_back(make_object<book>(4, "It", object_ptr<author>{}, 1986));
+  s_king->books.push_back(make_object<book>(5, "Misery", object_ptr<author>{}, 1987));
+  s_king->books.push_back(make_object<book>(6, "The Dark Tower: The Gunslinger", object_ptr<author>{}, 1982));
+
+  const auto contexts_by_type = to_contexts_by_name(scm, db->dialect());
+  delete_query_builder<author> dqb(scm, contexts_by_type);
+
+  auto build_result = dqb.build(s_king);
+  REQUIRE(build_result.is_ok());
+
+  const auto& stmts = *build_result;
+  REQUIRE_FALSE(stmts.empty());
+  REQUIRE(stmts.size() == 6);
+}
+
+TEST_CASE_METHOD(QueryFixture, "Test delete builder has many to many", "[query][delete_query_builder][many_to_many]") {
+  schema scm;
+  const auto result = scm.attach<recipe>("recipes")
+    .and_then( [&scm] { return scm.attach<ingredient>("ingredients"); } );
+  REQUIRE(result.is_ok());
+
+  std::vector ingredients {
+    make_object<ingredient>(1, "Apple"),
+    make_object<ingredient>(2, "Strawberry"),
+    make_object<ingredient>(3, "Pineapple"),
+    make_object<ingredient>(4, "Sugar"),
+    make_object<ingredient>(5, "Flour"),
+    make_object<ingredient>(6, "Butter"),
+    make_object<ingredient>(7, "Beans")
+  };
+
+  for (auto &i : ingredients) {
+    i.change_state(object_state::Persistent);
+  }
+
+  std::vector recipes {
+    make_object<recipe>(1, "Apple Pie", std::vector{ingredients[0], ingredients[3], ingredients[4]}),
+    make_object<recipe>(2, "Strawberry Cake", std::vector{ingredients[5], ingredients[6]}),
+    make_object<recipe>(3, "Pineapple Pie", std::vector{ingredients[0], ingredients[1], ingredients[2]})
+  };
+
+  for (auto &r : recipes) {
+    r.change_state(object_state::Persistent);
+  }
+
+  const auto contexts_by_type = to_contexts_by_name(scm, db->dialect());
+  delete_query_builder<recipe> dqb(scm, contexts_by_type);
+
+  auto build_result = dqb.build(recipes[0]);
+  REQUIRE(build_result.is_ok());
+
+  const auto& stmts = *build_result;
+  REQUIRE_FALSE(stmts.empty());
+  REQUIRE(stmts.size() == 7);
+}

test/orm/query/InsertQueryBuilderTest.cpp

@@ -6,13 +6,11 @@
 #include "matador/sql/connection.hpp"
 #include "matador/sql/interface/connection_impl.hpp"
 
-#include "matador/query/query_contexts.hpp"
-#include "matador/query/query.hpp"
 #include "matador/query/schema.hpp"
 
 #include "matador/query/insert_query_builder.hpp"
 
-#include "../backend/test_backend_service.hpp"
+#include "QueryFixture.hpp"
 
 #include "../../models/author.hpp"
 #include "../../models/book.hpp"
@@ -24,58 +22,15 @@ using namespace matador::object;
 using namespace matador::sql;
 using namespace matador::query;
 using namespace matador::utils;
+using namespace matador::test;
 
-std::unordered_map<std::type_index, query_contexts> to_contexts_by_name(const schema& scm, const dialect& d) {
-  std::unordered_map<std::type_index, query_contexts> contexts_by_type;
-  for (const auto &[type, node] : scm) {
-    query_contexts queries;
-
-    // SELECT all
-    queries.select_all = select(node.table())
-      .from(node.name())
-      .compile(d);
-    if (node.table().has_primary_key()) {
-      // SELECT one
-      queries.select_one = select(node.table())
-        .from(node.name())
-        .where(*node.table().primary_key_column() == _)
-        .compile(d);
-      // UPDATE one
-      auto update_set = update(node.table());
-      for (const auto &col: node.table().columns()) {
-        update_set.set(col, _);
-      }
-      queries.update_one = update_set.where(*node.table().primary_key_column() == _)
-        .compile(d);
-      // DELETE one
-      queries.delete_one = remove()
-        .from(node.name())
-        .where(*node.table().primary_key_column() == _)
-        .compile(d);
-    }
-    // INSERT one
-    queries.insert = insert()
-      .into(node.name(), node.table())
-      .values(generator::placeholders(node.table().columns().size()))
-      .compile(d);
-
-    contexts_by_type[node.node().type_index()] = queries;
-  }
-  
-  return contexts_by_type;
-}
-
-TEST_CASE("insert query builder test", "[query][insert_query_builder]") {
-  using namespace matador::test;
-  backend_provider::instance().register_backend("noop", std::make_unique<orm::test_backend_service>());
-  connection db("noop://noop.db");
-
+TEST_CASE_METHOD(QueryFixture, "insert query builder test", "[query][insert_query_builder]") {
   schema scm;
   auto result = scm.attach<airplane>("airplanes")
     .and_then( [&scm] { return scm.attach<flight>("flights"); } );
   REQUIRE(result);
 
-  const auto contexts_by_type = to_contexts_by_name(scm, db.dialect());
+  const auto contexts_by_type = to_contexts_by_name(scm, db->dialect());
   insert_query_builder<airplane> iqb(scm, contexts_by_type);
 
   const auto a380 = make_object<airplane>(1, "Boeing", "A380"  );
@@ -86,11 +41,7 @@ TEST_CASE("insert query builder test", "[query][insert_query_builder]") {
   REQUIRE(stmts.size() == 1);
 }
 
-TEST_CASE("Test insert builder has many", "[query][insert_query_builder][has_many]") {
-  using namespace matador::test;
-  backend_provider::instance().register_backend("noop", std::make_unique<orm::test_backend_service>());
-  connection db("noop://noop.db");
-
+TEST_CASE_METHOD(QueryFixture, "Test insert builder has many", "[query][insert_query_builder][has_many]") {
   schema scm;
   const auto result = scm.attach<book>("books")
     .and_then( [&scm] { return scm.attach<author>("authors"); } );
@@ -104,7 +55,7 @@ TEST_CASE("Test insert builder has many", "[query][insert_query_builder][has_man
   s_king->books.push_back(make_object<book>(5, "Misery", object_ptr<author>{}, 1987));
   s_king->books.push_back(make_object<book>(6, "The Dark Tower: The Gunslinger", object_ptr<author>{}, 1982));
 
-  const auto contexts_by_type = to_contexts_by_name(scm, db.dialect());
+  const auto contexts_by_type = to_contexts_by_name(scm, db->dialect());
   insert_query_builder<author> iqb(scm, contexts_by_type);
 
   auto build_result = iqb.build(s_king);
@@ -115,11 +66,7 @@ TEST_CASE("Test insert builder has many", "[query][insert_query_builder][has_man
   REQUIRE(stmts.size() == 6);
 }
 
-TEST_CASE("Test insert builder has many to many", "[query][insert_query_builder][many_to_many]") {
-  using namespace matador::test;
-  backend_provider::instance().register_backend("noop", std::make_unique<orm::test_backend_service>());
-  connection db("noop://noop.db");
-
+TEST_CASE_METHOD(QueryFixture, "Test insert builder has many to many", "[query][insert_query_builder][many_to_many]") {
   schema scm;
   const auto result = scm.attach<recipe>("recipes")
     .and_then( [&scm] { return scm.attach<ingredient>("ingredients"); } );
@@ -141,7 +88,7 @@ TEST_CASE("Test insert builder has many to many", "[query][insert_query_builder]
     make_object<recipe>(3, "Pineapple Pie", std::vector{ingredients[0], ingredients[1], ingredients[2]})
   };
 
-  const auto contexts_by_type = to_contexts_by_name(scm, db.dialect());
+  const auto contexts_by_type = to_contexts_by_name(scm, db->dialect());
   insert_query_builder<recipe> iqb(scm, contexts_by_type);
 
   auto build_result = iqb.build(recipes[0]);

test/orm/query/QueryFixture.cpp

@@ -4,6 +4,9 @@
 
 #include "matador/sql/interface/connection_impl.hpp"
 
+#include "matador/query/basic_schema.hpp"
+#include "matador/query/schema_utils.hpp"
+
 namespace matador::test {
 
 QueryFixture::QueryFixture() {
@@ -12,4 +15,12 @@ QueryFixture::QueryFixture() {
   db = std::make_unique<sql::connection>("noop://noop.db");
 }
 
+std::unordered_map<std::type_index, query::query_contexts> QueryFixture::to_contexts_by_name(const query::basic_schema& scm, const sql::dialect& d) {
+  std::unordered_map<std::type_index, query::query_contexts> contexts_by_type;
+  for (const auto &[type, node] : scm) {
+    contexts_by_type[node.node().type_index()] = to_query_contexts(node, d);
+  }
+
+    return contexts_by_type;
+}
 }

test/orm/query/QueryFixture.hpp

@@ -3,8 +3,14 @@
 
 #include "matador/sql/connection.hpp"
 
+#include "matador/query/query_contexts.hpp"
+
 #include <memory>
 
+namespace matador::query {
+class basic_schema;
+}
+
 namespace matador::test {
 
 class QueryFixture {
@@ -12,6 +18,9 @@ public:
   QueryFixture();
   ~QueryFixture() = default;
 
+protected:
+  static std::unordered_map<std::type_index, query::query_contexts> to_contexts_by_name(const query::basic_schema& scm, const sql::dialect& d) ;
+
 protected:
   std::unique_ptr<sql::connection> db;
 };