handle many-to-many relations separately when process entities

test/models/author.hpp

@@ -3,10 +3,14 @@
 
 #include "matador/utils/access.hpp"
 
+#include "matador/sql/entity.hpp"
+
 #include <string>
 
 namespace matador::test {
 
+struct book;
+
 struct author
 {
   unsigned long id{};
@@ -27,7 +31,7 @@ struct author
     field::attribute(op, "date_of_birth", date_of_birth, 31);
     field::attribute(op, "year_of_birth", year_of_birth);
     field::attribute(op, "distinguished", distinguished);
-    field::has_many(op, "books", books, "author_id", "id", utils::fetch_type::LAZY);
+    field::has_many(op, books, "author_id", utils::fetch_type::LAZY);
   }
 };
 

test/models/order.hpp

@@ -42,7 +42,7 @@ struct order
     field::attribute(op, "ship_region", ship_region, 255);
     field::attribute(op, "ship_postal_code", ship_postal_code, 255);
     field::attribute(op, "ship_country", ship_country, 255);
-    field::has_many(op, "order_details", order_details_, utils::fetch_type::EAGER);
+    field::has_many(op, order_details_, "order_id", utils::fetch_type::EAGER);
   }
 };
 

test/models/recipe.hpp

@@ -6,6 +6,7 @@
 #include "matador/utils/foreign_attributes.hpp"
 
 #include "matador/sql/entity.hpp"
+#include "matador/sql/has_many_to_many_relation.hpp"
 
 #include <string>
 
@@ -23,7 +24,7 @@ struct ingredient
     namespace field = matador::utils::access;
     field::primary_key(op, "id", id);
     field::attribute(op, "name", name, 255);
-    field::has_many(op, "recipes", recipes, "ingredient_id", "recipe_id", utils::fetch_type::EAGER);
+    field::has_many_to_many(op, "recipe_ingredients", recipes, "ingredient_id", "recipe_id", utils::fetch_type::EAGER);
   }
 };
 
@@ -38,21 +39,15 @@ struct recipe
     namespace field = matador::utils::access;
     field::primary_key(op, "id", id);
     field::attribute(op, "name", name, 255);
-    field::has_many(op, "ingredients", ingredients, "recipe_id", "ingredient_id", utils::fetch_type::EAGER);
+    field::has_many_to_many(op, "recipe_ingredients", ingredients, utils::fetch_type::LAZY);
   }
 };
 
-struct recipe_ingredient
+class recipe_ingredient : public sql::has_many_to_many_relation<recipe, ingredient>
 {
-  sql::entity<recipe> recipe_;
-  sql::entity<ingredient> ingredient_;
-
-  template<class Operator>
-  void process(Operator &op) {
-    namespace field = matador::utils::access;
-    field::belongs_to(op, "recipe_id", recipe_, utils::default_foreign_attributes);
-    field::belongs_to(op, "ingredient_id", ingredient_, utils::default_foreign_attributes);
-  }
+public:
+  recipe_ingredient()
+  : has_many_to_many_relation("recipe_id", "ingredient_id") {}
 };
 
 }