/**
  * Gets all the attendees for a transaction (by using the esp_registration as a join table)
  * @param EE_Transaction/int $transaction_id_or_obj EE_Transaction or its ID
  * @return EE_Attendee[]
  */
 public function get_attendees_for_transaction($transaction_id_or_obj)
 {
     return $this->get_all(array(array('Registration.Transaction.TXN_ID' => $transaction_id_or_obj instanceof EE_Transaction ? $transaction_id_or_obj->ID() : $transaction_id_or_obj)));
 }
 /**
  * Gets all the attendees for a transaction (by using the esp_registration as a join table)
  * @param EE_Transaction/int $transaction_id_or_obj EE_Transaction or its ID
  * @param string $output
  * @return EE_Attendee[]
  */
 public function get_attendees_for_transaction($transaction_id_or_obj)
 {
     if ($transaction_id_or_obj instanceof EE_Transaction) {
         $transaction_id = $transaction_id_or_obj->ID();
     } else {
         $transaction_id = $transaction_id;
     }
     return $this->get_all(array(array('Registration.Transaction.TXN_ID' => $transaction_id)));
 }