fixed has one definitions

test/models/order_details.hpp

@@ -3,6 +3,7 @@
 
 #include "product.hpp"
 
+#include "matador/object/collection.hpp"
 #include "matador/object/object_ptr.hpp"
 
 #include "matador/utils/foreign_attributes.hpp"
@@ -13,14 +14,14 @@ struct order;
 struct order_details {
   unsigned int order_details_id;
   object::object_ptr<order> order_;
-  object::object_ptr<product> product_;
+  object::collection<object::object_ptr<product>> products_;
 
   template<class Operator>
   void process(Operator &op) {
     namespace field = matador::access;
     field::primary_key(op, "order_details_id", order_details_id);
     field::belongs_to(op, "order_id", order_, utils::CascadeNoneFetchLazy);
-    field::has_one(op, "product_id", product_, utils::CascadeNoneFetchLazy);
+    field::has_many(op, "order_products", products_, "product_id", utils::CascadeNoneFetchLazy);
   }
 };
 }