/**
  * save mterial assignment
  * @return void
  */
 protected function deassign()
 {
     if (!$_POST['item_ids']) {
         ilUtil::sendFailure($this->lng->txt('select_one'), true);
         $this->ctrl->redirect($this, 'show');
         return false;
     }
     if (count($_POST['item_ids'])) {
         include_once 'Services/Tracking/classes/class.ilLPCollections.php';
         ilLPCollections::deactivate($this->getObjId(), $_POST['item_ids']);
         // refresh learning progress
         include_once "./Services/Tracking/classes/class.ilLPStatusWrapper.php";
         ilLPStatusWrapper::_refreshStatus($this->getObjId());
     }
     ilUtil::sendSuccess($this->lng->txt('trac_settings_saved'), true);
     $this->ctrl->redirect($this, 'show');
 }