/**
  * Get all result rows as an array.
  *
  * @return array
  */
 public function getAll()
 {
     $res = array();
     if (empty($this->_result)) {
         return json_encode(array());
     }
     foreach ($this->_result as $row) {
         $row = ModelHelper::removeNumericKeys($row);
         $res[] = $row;
     }
     return json_encode($res);
 }