public function addPopulationTarget(TCombo $alvo, $model, $frm, $key_busca, $value, $key_valor, $ordercolumn = null)
 {
     if ($this->changeaction) {
         // carrega objetos do banco de dados
         TTransaction::open($this->banco);
         // instancia um repositório de Estado
         $repository = new TRepository($model);
         $criteria = new TCriteria();
         $criteria->setProperty('order', isset($ordercolumn) ? $ordercolumn : $key_busca);
         $criteria->add(new TFilter($key_busca, '=', $key_valor));
         // carrega todos objetos
         $collection = $repository->{$model};
         $items = array();
         foreach ($collection as $object) {
             $items[$object->{$key}] = $object->{$value};
         }
         TCombo::reload($frm, $alvo->getName(), $items);
         TTransaction::close();
     } else {
         throw new Exception('you need delcare changeaction first');
     }
 }