/**
  * Lock or unlock an attendance
  * render to attendance_list view
  * @param string  action (lock_attendance or unlock_attendance)
  * @param int     attendance id
  * render to attendance_list view
  */
 public function lock_attendance($action, $attendance_id)
 {
     $attendance = new Attendance();
     $attendance_id = intval($attendance_id);
     if ($action == 'lock_attendance') {
         $result = $attendance->lock_attendance($attendance_id);
     } else {
         $result = $attendance->lock_attendance($attendance_id, false);
     }
     if ($result) {
         $message['message_locked_attendance'] = true;
     }
     $this->attendance_list();
 }