code: 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;
      }
docs: Requires a query object and will fetch related models with any parameters defined
  on that query. If the attribute being fetched is not a model relationship, then it will
  just execute the query and return the result.
  
  @return mixed