public function listAction()
 {
     $discountTable = new DiscountTable();
     $discountTableIterator = $discountTable->getIteratorByDistinctGuid();
     $rows = array();
     foreach ($discountTableIterator as $discount) {
         $rows[] = $this->_generateRowData($discount);
     }
     $json = Zend_Controller_Action_HelperBroker::getStaticHelper('json');
     $json->suppressExit = true;
     $json->direct(array('rows' => $rows));
 }