has many primitive relation progress

include/matador/object/many_to_many_relation.hpp

@@ -46,6 +46,11 @@ public:
     many_to_relation(std::string local_name, std::string remote_name)
     : local_name_(std::move(local_name))
     , type_name_(std::move(remote_name)) {}
+    many_to_relation(std::string local_name, std::string remote_name, const object_ptr<LocalType>& local, const Type& value)
+    : local_name_(std::move(local_name))
+    , type_name_(std::move(remote_name))
+    , local_(local)
+    , value_(value){}
 
     template<class Operator>
     void process(Operator &op) {

include/matador/object/relation_completer.hpp

@@ -227,9 +227,11 @@ void relation_completer<Type, Observers...>::on_has_many(const char *id, Collect
   using value_type = typename CollectionType::value_type;
   using relation_value_type = many_to_relation<Type, value_type>;
 
+  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_, id, [join_column] {
     return std::make_unique<relation_value_type>(join_column, "value");
-  }, {});
+  }, std::move(observers));
   const auto result = repo_.attach_node(node.release(), "");
   if (!result) {
     // Todo: throw internal exception