public function getCoField($con = null)
 {
     if ($this->aCoField === null && $this->field_id !== null) {
         include_once 'lib/model/om/BaseCoFieldPeer.php';
         $this->aCoField = CoFieldPeer::retrieveByPK($this->field_id, $con);
     }
     return $this->aCoField;
 }