Model::belongs_to PHP Метод

    protected function belongs_to($associated_class_name, $foreign_key_name = null, $foreign_key_name_in_associated_models_table = null, $connection_name = null)
    {
        $associated_table_name = self::_get_table_name(self::$auto_prefix_models . $associated_class_name);
        $foreign_key_name = self::_build_foreign_key_name($foreign_key_name, $associated_table_name);
        $associated_object_id = $this->{$foreign_key_name};
        $desired_record = null;
        if (is_null($foreign_key_name_in_associated_models_table)) {
            //"{$associated_table_name}.primary_key = {$associated_object_id}"
            //NOTE: primary_key is a placeholder for the actual primary key column's name
            //in $associated_table_name
            $desired_record = self::factory($associated_class_name, $connection_name)->where_id_is($associated_object_id);
        } else {
            //"{$associated_table_name}.{$foreign_key_name_in_associated_models_table} = {$associated_object_id}"
            $desired_record = self::factory($associated_class_name, $connection_name)->where($foreign_key_name_in_associated_models_table, $associated_object_id);
        }
        return $desired_record;
    }