From bcec740d601f4dac62d0e2cf6f15f06b4961e5be Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sascha=20K=C3=BChl?= <s.kuehl@tms-bonn.de>
Date: Thu, 29 Jan 2026 17:23:16 +0100
Subject: [PATCH] collection_resolver progress

---
 backends/postgres/src/postgres_connection.cpp |  3 +-
 backends/postgres/src/postgres_statement.cpp  |  5 ++-
 demo/sandbox.cpp                              |  9 ++++
 include/matador/net/os.hpp                    |  2 -
 include/matador/object/collection_proxy.hpp   |  8 +++-
 .../object/collection_resolver_factory.hpp    |  2 +-
 .../query/intermediates/fetchable_query.hpp   |  9 ++--
 .../query/query_collection_resolver.hpp       | 41 ++++++-------------
 include/matador/query/schema.hpp              | 18 ++++++--
 .../sql/internal/query_result_impl.hpp        |  9 ++--
 include/matador/sql/query_context.hpp         |  2 +
 include/matador/utils/convert.hpp             | 11 +++--
 include/matador/utils/os.hpp                  |  8 ++++
 source/core/utils/os.cpp                      | 20 +++++++--
 .../query/intermediates/fetchable_query.cpp   |  6 ++-
 .../orm/query/internal/query_result_impl.cpp  |  4 +-
 todo.md                                       |  2 +-
 17 files changed, 100 insertions(+), 59 deletions(-)

diff --git a/backends/postgres/src/postgres_connection.cpp b/backends/postgres/src/postgres_connection.cpp
index b8c00e8..55bb4f2 100644
--- a/backends/postgres/src/postgres_connection.cpp
+++ b/backends/postgres/src/postgres_connection.cpp
@@ -111,7 +111,8 @@ utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> postgres_co
 
   return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res),
                                                                     std::move(prototype),
-                                                                    context.resolver));
+                                                                    context.resolver,
+                                                                    context.result_type));
 }
 
 std::string postgres_connection::generate_statement_name(const sql::query_context &query) {
diff --git a/backends/postgres/src/postgres_statement.cpp b/backends/postgres/src/postgres_statement.cpp
index 38b84b4..9159859 100644
--- a/backends/postgres/src/postgres_statement.cpp
+++ b/backends/postgres/src/postgres_statement.cpp
@@ -60,7 +60,10 @@ utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> postgres_st
     return utils::failure(make_error(sql::error_code::FETCH_FAILED, res, db_, "Failed to fetch statement", query_.sql));
   }
 
-  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res), query_.prototype, query_.resolver));
+  return utils::ok(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res),
+                                                                    query_.prototype,
+                                                                    query_.resolver,
+                                                                    query_.result_type));
 }
 
 std::unique_ptr<utils::attribute_writer> postgres_statement::create_binder() const {
diff --git a/demo/sandbox.cpp b/demo/sandbox.cpp
index 7b88ecc..4f41883 100644
--- a/demo/sandbox.cpp
+++ b/demo/sandbox.cpp
@@ -1,4 +1,7 @@
 #include "matador/object/repository.hpp"
+#include "matador/object/collection.hpp"
+
+#include "matador/sql/resolver_service.hpp"
 
 #include "matador/logger/log_manager.hpp"
 
@@ -131,6 +134,12 @@ int main() {
   // logger::default_min_log_level(logger::log_level::LVL_DEBUG);
   // logger::add_log_sink(logger::create_stdout_sink());
 
+  sql::resolver_service rs;
+
+  std::weak_ptr cr = rs.collection_resolver<object::object_ptr<names>>( typeid(person), "names" );
+  utils::identifier id{1};
+
+  object::collection_proxy cp(cr, id);
   {
     // has_many with builtin-type
     object::repository repo;
diff --git a/include/matador/net/os.hpp b/include/matador/net/os.hpp
index d7a6acd..b7f19e2 100644
--- a/include/matador/net/os.hpp
+++ b/include/matador/net/os.hpp
@@ -1,8 +1,6 @@
 #ifndef MATADOR_NET_OS_HPP
 #define MATADOR_NET_OS_HPP
 
-#include "matador/net/export.hpp"
-
 #include <cstdio>
 
 #if _WIN32
diff --git a/include/matador/object/collection_proxy.hpp b/include/matador/object/collection_proxy.hpp
index 16f2f97..99f4615 100644
--- a/include/matador/object/collection_proxy.hpp
+++ b/include/matador/object/collection_proxy.hpp
@@ -1,12 +1,13 @@
 #ifndef MATADOR_COLLECTION_PROXY_HPP
 #define MATADOR_COLLECTION_PROXY_HPP
 
-#include <atomic>
 
 #include "matador/object/collection_resolver.hpp"
 
 #include "matador/utils/identifier.hpp"
 
+#include <atomic>
+#include <mutex>
 #include <vector>
 
 namespace matador::object {
@@ -33,13 +34,15 @@ public:
     return owner_id_;
   }
   const std::vector<Type>& items() const {
+    resolve();
     return items_;
   }
   std::vector<Type>& items() {
+    resolve();
     return items_;
   }
 private:
-  void resolve() const {
+  void resolve() {
     if (loaded_) {
       return;
     }
@@ -53,6 +56,7 @@ private:
     }
 
     items_ = resolver->resolve(owner_id_);
+    loaded_ = true;
   }
 
 private:
diff --git a/include/matador/object/collection_resolver_factory.hpp b/include/matador/object/collection_resolver_factory.hpp
index b01d06a..679323d 100644
--- a/include/matador/object/collection_resolver_factory.hpp
+++ b/include/matador/object/collection_resolver_factory.hpp
@@ -16,7 +16,7 @@ class collection_resolver_factory : public abstract_collection_resolver_factory
 public:
   template<class Type>
   [[nodiscard]] std::shared_ptr<collection_resolver<Type>> resolver(const std::type_index &root_type, const std::string &collection_name) const {
-    const auto res = acquire_collection_resolver(typeid(Type), root_type, collection_name);
+    const auto res = acquire_collection_resolver(root_type, typeid(Type), collection_name);
     if (!res) {
       return std::dynamic_pointer_cast<collection_resolver<Type>>(res);
     }
diff --git a/include/matador/query/intermediates/fetchable_query.hpp b/include/matador/query/intermediates/fetchable_query.hpp
index 6c8a144..95f23bd 100644
--- a/include/matador/query/intermediates/fetchable_query.hpp
+++ b/include/matador/query/intermediates/fetchable_query.hpp
@@ -26,7 +26,7 @@ protected:
 public:
   template < class Type >
   utils::result<sql::query_result<Type>, utils::error> fetch_all(sql::executor &exec) {
-    auto result = fetch(exec);
+    auto result = fetch(exec, typeid(Type));
     if (!result.is_ok()) {
       return utils::failure(result.err());
     }
@@ -40,9 +40,8 @@ public:
   [[nodiscard]] utils::result<sql::query_result<sql::record>, utils::error> fetch_all(const sql::executor &exec) const;
 
   template < class Type >
-  utils::result<object::object_ptr<Type>, utils::error> fetch_one(sql::executor &exec)
-  {
-    auto result = fetch(exec);
+  utils::result<object::object_ptr<Type>, utils::error> fetch_one(sql::executor &exec) {
+    auto result = fetch(exec, typeid(Type));
     if (!result.is_ok()) {
       return utils::failure(result.err());
     }
@@ -83,7 +82,7 @@ public:
   [[nodiscard]] sql::query_context compile(const sql::dialect &d) const;
 
 private:
-  [[nodiscard]] utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> fetch(const sql::executor &exec) const;
+  [[nodiscard]] utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> fetch(const sql::executor &exec, const std::type_index& index) const;
 };
 
 }
diff --git a/include/matador/query/query_collection_resolver.hpp b/include/matador/query/query_collection_resolver.hpp
index d89f2b2..d879933 100644
--- a/include/matador/query/query_collection_resolver.hpp
+++ b/include/matador/query/query_collection_resolver.hpp
@@ -6,9 +6,6 @@
 #include "matador/sql/internal/identifier_statement_binder.hpp"
 #include "matador/sql/statement.hpp"
 
-#include "matador/query/table.hpp"
-#include "matador/query/select_query_builder.hpp"
-
 namespace matador::sql {
 class executor;
 }
@@ -17,47 +14,33 @@ namespace matador::query {
 template<typename Type>
 class query_collection_resolver : public object::collection_resolver<Type> {
 public:
-  explicit query_collection_resolver(const basic_schema &repo, sql::executor& exec, const table &tab, std::string pk_name, const std::type_index& root_type, std::string join_column)
+  explicit query_collection_resolver(sql::statement &&stmt, const std::type_index& root_type, std::string join_column)
   : object::collection_resolver<Type>(root_type, join_column)
-  , executor_(exec)
-  , schema_(repo)
-  , table_(tab)
-  , pk_name_(std::move(pk_name))
-  , join_column_(std::move(join_column))
+  , stmt_(std::move(stmt))
   {}
 
   std::vector<Type> resolve(const utils::identifier &id) override;
 protected:
-  sql::executor& executor_;
-  const basic_schema &schema_;
-  const table &table_;
-  std::string pk_name_;
-  std::string join_column_;
+  sql::statement stmt_;
   std::type_index index{typeid(Type)};
 };
 
 template<typename Type>
 std::vector<Type> query_collection_resolver<Type>::resolve(const utils::identifier &id) {
-  const auto *pk_column = table_[pk_name_];
-  const auto *join_column = table_[join_column_];
-
-  auto stmt = query::select({*pk_column})
-    .from(table_)
-    .where(*join_column == id)
-    .prepare(executor_);
-
-  if (!stmt) {
-    return {};
-  }
-
-  sql::identifier_statement_binder binder(*stmt);
+  sql::identifier_statement_binder binder(stmt_);
   binder.bind(id);
 
-  auto result = stmt->template fetch_one_raw<Type>();
+  auto result = stmt_.fetch();
   if (!result) {
     return {};
   }
-  return {};
+  std::vector<Type> out;
+  for (const auto &i: *result) {
+    // Todo: convert the first value of record into an utils::identifier
+    //       then create a object_proxy<Type>(resolver, identifier)
+    // out.emplace_back(resolver, identifier);
+  }
+  return out;
 }
 }
 #endif //MATADOR_QUERY_CONTAINER_RESOLVER_HPP
\ No newline at end of file
diff --git a/include/matador/query/schema.hpp b/include/matador/query/schema.hpp
index 2493bfd..172b955 100644
--- a/include/matador/query/schema.hpp
+++ b/include/matador/query/schema.hpp
@@ -51,7 +51,19 @@ public:
   {}
 
   std::shared_ptr<object::abstract_collection_resolver> produce(sql::executor &exec) override {
-    return std::make_shared<query_collection_resolver<Type>>(repo_, exec, table_, std::move(pk_name_), root_type(), collection_name());
+    const auto *pk_column = table_[pk_name_];
+    const auto *join_column = table_[collection_name()];
+
+    auto stmt = query::select({*pk_column})
+      .from(table_)
+      .where(*join_column == utils::_)
+      .prepare(exec);
+
+    if (!stmt) {
+      return {};
+    }
+
+    return std::make_shared<query_collection_resolver<Type>>(stmt.release(), root_type(), collection_name());
   }
 
 private:
@@ -201,13 +213,13 @@ public:
       throw query_builder_exception{query_build_error::MissingPrimaryKey};
     }
 
-    auto producer = std::make_unique<query_collection_resolver_producer<typename CollectionType::value_type::value_type>>(
+    auto producer = std::make_unique<query_collection_resolver_producer<typename CollectionType::value_type>>(
       schema_,
       it->second.table(),
       it->second.node().info().primary_key_attribute()->name(),
       root_type_,
       join_column);
-    const sql::composite_key key{root_type_, typeid(typename CollectionType::value_type::value_type), join_column};
+    const sql::composite_key key{root_type_, typeid(typename CollectionType::value_type), join_column};
     schema_.collection_resolver_producers_[key] = std::move(producer);
   }
 
diff --git a/include/matador/sql/internal/query_result_impl.hpp b/include/matador/sql/internal/query_result_impl.hpp
index 0fdcc6f..a4190ab 100644
--- a/include/matador/sql/internal/query_result_impl.hpp
+++ b/include/matador/sql/internal/query_result_impl.hpp
@@ -78,6 +78,7 @@ public:
   query_result_impl(std::unique_ptr<query_result_reader> &&reader,
                     std::vector<object::attribute> prototype,
                     const std::shared_ptr<resolver_service>& resolver,
+                    const std::type_index& result_type,
                     size_t column_index = 0);
 
   template<typename ValueType>
@@ -127,13 +128,12 @@ public:
   template<class CollectionType>
   void on_has_many(const char * /*id*/, CollectionType &cont, const char *join_column, const utils::foreign_attributes &attr, std::enable_if_t<object::is_object_ptr<typename CollectionType::value_type>::value> * = nullptr) {
     using value_type = typename CollectionType::value_type::value_type;
-    auto resolver = resolver_->collection_resolver<value_type>(type_stack_.top(), join_column);
+    auto resolver = resolver_->collection_resolver<typename CollectionType::value_type>(result_type_, join_column);
     auto object_resolver = resolver_->object_resolver<value_type>();
 
     std::vector<typename CollectionType::value_type> objects;
     if (attr.fetch() == utils::fetch_type::Lazy) {
-
-      // pk_reader_.read(*id, column_index_++);
+      cont.reset(std::make_shared<object::collection_proxy<typename CollectionType::value_type>>(resolver, current_pk_));
     } else {
       const auto ti = std::type_index(typeid(value_type));
       auto obj = std::make_shared<typename CollectionType::value_type::value_type>();
@@ -227,7 +227,8 @@ protected:
   size_t column_index_ = 0;
   std::vector<object::attribute> prototype_;
   std::unique_ptr<query_result_reader> reader_;
-  std::shared_ptr<sql::resolver_service> resolver_;
+  std::shared_ptr<resolver_service> resolver_;
+  const std::type_index result_type_;
   internal::identifier_reader id_reader_;
   detail::pk_reader pk_reader_;
   std::stack<std::type_index> type_stack_;
diff --git a/include/matador/sql/query_context.hpp b/include/matador/sql/query_context.hpp
index 55a1c17..47f4554 100644
--- a/include/matador/sql/query_context.hpp
+++ b/include/matador/sql/query_context.hpp
@@ -41,7 +41,9 @@ struct query_context {
   std::vector<object::attribute> prototype{};
   std::vector<std::string> bind_vars{};
   std::vector<utils::database_type> bind_types{};
+  // Data for resolving query result
   std::shared_ptr<resolver_service> resolver{};
+  std::type_index result_type = typeid(void);
 };
 }
 
diff --git a/include/matador/utils/convert.hpp b/include/matador/utils/convert.hpp
index 0bacd9f..eca0e67 100644
--- a/include/matador/utils/convert.hpp
+++ b/include/matador/utils/convert.hpp
@@ -3,6 +3,7 @@
 
 #include "matador/utils/types.hpp"
 #include "matador/utils/result.hpp"
+#include "matador/utils/os.hpp"
 
 #include <array>
 #include <charconv>
@@ -467,18 +468,20 @@ template < typename DestType>
 result<DestType, conversion_error> to(const timestamp_type_t &source, std::enable_if_t<std::is_same_v<time_type_t, DestType>>* = nullptr) {
   const std::time_t tt = std::chrono::system_clock::to_time_t(source);
 
-  const std::tm* result = std::localtime(&tt);
+  std::tm result;
+  matador::os::localtime(tt, result);
 
-  return ok(time_type_t{static_cast<uint8_t>(result->tm_hour), static_cast<uint8_t>(result->tm_min), static_cast<uint8_t>(result->tm_sec)});
+  return ok(time_type_t{static_cast<uint8_t>(result.tm_hour), static_cast<uint8_t>(result.tm_min), static_cast<uint8_t>(result.tm_sec)});
 }
 
 template < typename DestType>
 result<DestType, conversion_error> to(const timestamp_type_t &source, std::enable_if_t<std::is_same_v<date_type_t, DestType>>* = nullptr) {
   const std::time_t tt = std::chrono::system_clock::to_time_t(source);
 
-  const std::tm* result = std::localtime(&tt);
+  std::tm result;
+  matador::os::localtime(tt, result);
 
-  return ok(date_type_t{result->tm_year + 1900, static_cast<uint8_t>(result->tm_mon + 1), static_cast<uint8_t>(result->tm_mday)});
+  return ok(date_type_t{result.tm_year + 1900, static_cast<uint8_t>(result.tm_mon + 1), static_cast<uint8_t>(result.tm_mday)});
 }
 
 }
diff --git a/include/matador/utils/os.hpp b/include/matador/utils/os.hpp
index b3e0365..d78993c 100644
--- a/include/matador/utils/os.hpp
+++ b/include/matador/utils/os.hpp
@@ -98,6 +98,14 @@ int sprintf(char* str, size_t s, const char* format, ARGS const&... args)
 
 MATADOR_UTILS_API char* strerror(int err, char* errbuf, size_t bufsize);
 
+/**
+ * Multi platform version of localtime
+ *
+ * @param in time_t value to be converted
+ * @param out converted value
+ */
+MATADOR_UTILS_API void localtime(const time_t &in, struct tm &out);
+
 /// @endcond
 
 }
diff --git a/source/core/utils/os.cpp b/source/core/utils/os.cpp
index 1e8e8fc..7718974 100644
--- a/source/core/utils/os.cpp
+++ b/source/core/utils/os.cpp
@@ -1,10 +1,12 @@
 #include "matador/utils/os.hpp"
 
 #include <sys/stat.h>
-#include <cstring>
-#include <vector>
-#include <stdexcept>
+#include <ctime>
+
 #include <algorithm>
+#include <cstring>
+#include <stdexcept>
+#include <vector>
 
 #ifdef _WIN32
 #include <io.h>
@@ -357,4 +359,16 @@ char* strerror(int err, char* errbuf, size_t bufsize)
 #endif
 }
 
+void localtime(const time_t &in, struct tm &out) {
+#if defined(__unix__)
+  localtime_r(&in, &out);
+#elif defined(_MSC_VER)
+  errno_t err = localtime_s(&out, &in);
+#else
+  static std::mutex mtx;
+  std::lock_guard<std::mutex> lock(mtx);
+  out = *std::localtime(&in);
+#endif
+}
+
 }
diff --git a/source/orm/query/intermediates/fetchable_query.cpp b/source/orm/query/intermediates/fetchable_query.cpp
index 04e1e1f..b9f57c3 100644
--- a/source/orm/query/intermediates/fetchable_query.cpp
+++ b/source/orm/query/intermediates/fetchable_query.cpp
@@ -28,7 +28,8 @@ sql::record *create_prototype(const std::vector<object::attribute> &prototype) {
 }
 utils::result<sql::query_result<sql::record>, utils::error> fetchable_query::fetch_all(const sql::executor &exec) const {
   query_builder compiler;
-  const auto ctx = compiler.compile(*context_, exec.dialect(), std::nullopt);
+  auto ctx = compiler.compile(*context_, exec.dialect(), std::nullopt);
+  ctx.resolver = exec.resolver();
   return exec.fetch(ctx)
     .and_then([](auto &&res) {
       const auto prototype = res->prototype();
@@ -67,9 +68,10 @@ sql::query_context fetchable_query::compile(const sql::dialect &d) const {
   return compiler.compile(*context_, d, std::nullopt);
 }
 
-utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> fetchable_query::fetch(const sql::executor &exec) const {
+utils::result<std::unique_ptr<sql::query_result_impl>, utils::error> fetchable_query::fetch(const sql::executor &exec, const std::type_index& index) const {
   auto ctx = compile(exec.dialect());
   ctx.resolver = exec.resolver();
+  ctx.result_type = index;
   return exec.fetch(ctx);
 }
 
diff --git a/source/orm/query/internal/query_result_impl.cpp b/source/orm/query/internal/query_result_impl.cpp
index 8d4e290..531e26a 100644
--- a/source/orm/query/internal/query_result_impl.cpp
+++ b/source/orm/query/internal/query_result_impl.cpp
@@ -9,12 +9,14 @@ detail::pk_reader::pk_reader(query_result_reader &reader)
 
 query_result_impl::query_result_impl(std::unique_ptr<query_result_reader> &&reader,
                                      std::vector<object::attribute> prototype,
-                                     const std::shared_ptr<sql::resolver_service>& resolver,
+                                     const std::shared_ptr<resolver_service>& resolver,
+                                     const std::type_index& result_type,
                                      const size_t column_index)
 : column_index_(column_index)
 , prototype_(std::move(prototype))
 , reader_(std::move(reader))
 , resolver_(resolver)
+, result_type_(result_type)
 , id_reader_(*reader_)
 , pk_reader_(*reader_) {
 }
diff --git a/todo.md b/todo.md
index 7fbc34d..c22d10a 100644
--- a/todo.md
+++ b/todo.md
@@ -2,7 +2,7 @@
 
 - move `prepare_*` methods from `dialect` to `query_compiler`
 - add `session_insert_builder` and `session_update_builder` (returning multiple statements)
-- finish fetch eager has-many/belongs-to relations
+- finish fetch eager many-to-many relations
 - implement lazy loading
 - implement polymorphic class hierarchies
 - finish `schema_repository` classes (move add/drop from `session` to `schema`)