has many primitive collection resolver

include/matador/query/query_collection_resolver.hpp

@@ -31,6 +31,46 @@ protected:
   std::shared_ptr<object::object_resolver<typename Type::value_type>> resolver_;
 };
 
+template<typename Type>
+class query_collection_primitive_resolver : public object::collection_resolver<Type> {
+public:
+  explicit query_collection_primitive_resolver(sql::statement &&stmt,
+                                               const std::type_index& root_type,
+                                               std::string join_column//,
+                                               /*const std::shared_ptr<object::object_resolver<typename Type::value_type>> &resolver*/)
+  : object::collection_resolver<Type>(root_type, join_column)
+  , stmt_(std::move(stmt))
+  // , resolver_(resolver)
+  {}
+
+  std::vector<Type> resolve(const utils::identifier &id) override {
+    sql::identifier_statement_binder binder(stmt_);
+    binder.bind(id);
+
+    auto result = stmt_.fetch();
+    if (!result) {
+      return {};
+    }
+    std::vector<Type> out;
+    for (auto &r : *result) {
+      // Todo: convert the first value of record into an utils::identifier
+      //       then create a object_proxy<Type>(resolver, identifier)
+      if (r.size() != 1) {
+        continue;
+      }
+      auto val = r.at<Type>(0);
+      if (val.has_value()) {
+        out.push_back(*val);
+      }
+    }
+    return out;
+  }
+protected:
+  sql::statement stmt_;
+  std::type_index index{typeid(Type)};
+  // std::shared_ptr<object::object_resolver<typename Type::value_type>> resolver_;
+};
+
 struct value_to_identifier{
   void operator()(const int8_t &x) { assign(x); }
   void operator()(const int16_t &x) { assign(x); }

include/matador/query/schema.hpp

@@ -54,6 +54,41 @@ private:
   std::string pk_name_;
 };
 
+template<typename Type>
+class query_collection_primitive_resolver_producer : public sql::collection_resolver_producer {
+public:
+  query_collection_primitive_resolver_producer() = default;
+  query_collection_primitive_resolver_producer(const basic_schema& repo, const table& tab, std::string value_name, const std::type_index& root_type, std::string join_column)
+  : collection_resolver_producer(root_type, typeid(Type), std::move(join_column))
+  , repo_(repo)
+  , table_(tab)
+  , value_name_(std::move(value_name))
+  {}
+
+  utils::result<sql::query_context, utils::error> build_query(const sql::dialect& d) override {
+    const auto *value_column = table_[value_name_];
+    const auto *join_column = table_[collection_name()];
+
+    const auto stmt = select({*value_column})
+      .from(table_)
+      .where(*join_column == utils::_)
+      .compile(d);
+
+    return utils::ok(stmt);
+  }
+
+  std::shared_ptr<object::abstract_collection_resolver> produce(sql::statement&& stmt, const sql::resolver_service& rs) override {
+    // const auto object_resolver = rs.object_resolver<typename Type::value_type>();
+
+    return std::make_shared<query_collection_primitive_resolver<Type>>(std::move(stmt), root_type(), collection_name()/*, object_resolver*/);
+  }
+
+private:
+  const basic_schema& repo_;
+  const table& table_;
+  std::string value_name_;
+};
+
 class producer_creator final {
 public:
   producer_creator(basic_schema& schema, const std::type_index& root_type)
@@ -94,7 +129,20 @@ 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) {}
+  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) {
+    const auto it = schema_.find(id);
+    if (it == schema_.end()) {
+      throw query_builder_exception{error_code::UnknownType, "Unknown type" + std::string{id}};
+    }
+    auto producer = std::make_unique<query_collection_primitive_resolver_producer<typename CollectionType::value_type>>(
+      schema_,
+      it->second.table(),
+      "value",
+      root_type_,
+      join_column);
+    const object::collection_composite_key key{root_type_, typeid(typename CollectionType::value_type), join_column};
+    schema_.collection_resolver_producers_[key] = std::move(producer);
+  }
 
   template<class CollectionType>
   void on_has_many_to_many(const char *id, CollectionType &, const char *join_column, const char *inverse_join_column, const utils::foreign_attributes &/*attr*/) {

test/backends/SessionInsertHasMany.cpp

@@ -1,5 +1,3 @@
-#include <utility>
-
 #include "catch2/catch_test_macros.hpp"
 
 #include "SessionFixture.hpp"
@@ -207,4 +205,8 @@ TEST_CASE_METHOD(SessionFixture, "Test insert object with has many primitive rel
   auto clist = *colorlist_result;
   REQUIRE(clist.is_persistent());
   REQUIRE(clist->colors.size() == 3);
+  std::vector<std::string> expected_colors{"red", "green", "blue"};
+  for (const auto &cstr: clist->colors) {
+    REQUIRE(std::find(expected_colors.begin(), expected_colors.end(), cstr) != expected_colors.end());
+  }
 }