protected function _getCustomValue($attributeName, $query, $loadMap = false)
    {
      $def = $this->model_attributes[$attributeName];
      $result = $this->_getRelation($attributeName, $query, $loadMap); //$this->_getAttributeData($attributeName, $query, $loadMap);

      if (!$result) {
        $result = $query->fetch();
      }
      
      return $result;
    }