/**
  * Update assignment
  *
  */
 public function updateAssignment()
 {
     global $tpl, $lng, $ilCtrl, $ilTabs;
     $ilTabs->activateTab("overview");
     $this->addOverviewSubTabs("list_assignments");
     $this->initAssignmentForm("edit");
     if ($this->form->checkInput()) {
         include_once "./Customizing/global/plugins/Services/Repository/RepositoryObject/Ephorus/classes/class.ilEphAssignment.php";
         // additional checks
         if ($_POST["start_time_cb"]) {
             // check whether start date is before end date
             $start_date = $this->form->getItemByPostVar("start_time")->getDate();
             $end_date = $this->form->getItemByPostVar("deadline")->getDate();
             if ($start_date->get(IL_CAL_UNIX) >= $end_date->get(IL_CAL_UNIX)) {
                 ilUtil::sendFailure($lng->txt("form_input_not_valid"), true);
                 $this->form->getItemByPostVar("start_time")->setAlert($lng->txt("rep_robj_xeph_start_date_should_be_before_end_date"));
                 $this->form->getItemByPostVar("deadline")->setAlert($lng->txt("rep_robj_xeph_start_date_should_be_before_end_date"));
                 $this->form->setValuesByPost();
                 $tpl->setContent($this->form->getHtml());
                 return;
             }
         }
         $ass = new ilEphAssignment($_GET["ass_id"]);
         $ass->setTitle($_POST["title"]);
         $ass->setInstruction($_POST["instruction"]);
         $ass->setEphorusId($this->object->getId());
         $ass->setMandatory($_POST["mandatory"]);
         if ($_POST["start_time_cb"]) {
             $date = $this->form->getItemByPostVar("start_time")->getDate();
             $ass->setStartTime($date->get(IL_CAL_UNIX));
         } else {
             $ass->setStartTime(null);
         }
         // deadline
         $date = $this->form->getItemByPostVar("deadline")->getDate();
         $ass->setDeadline($date->get(IL_CAL_UNIX));
         $ass->update($this->object);
         ilUtil::sendSuccess($lng->txt("msg_obj_modified"), true);
         $ilCtrl->redirect($this, "listAssignments");
     } else {
         $this->form->setValuesByPost();
         $tpl->setContent($this->form->getHtml());
     }
 }