public ActionResult Delete(long?parentId, long id)
        {
            var assignmentGroup = _assignmentGroupRepository.GetById(id);

            if (!_assignmentGroupService.IsDeactivable(assignmentGroup))
            {
                ModelState.AddModelError("AssignmentGroup", _localizationService.GetResource("Common.NotDeactivable"));
            }

            if (ModelState.IsValid)
            {
                //soft delete
                _assignmentGroupRepository.DeactivateAndCommit(assignmentGroup);
                //notification
                SuccessNotification(_localizationService.GetResource("Record.Deleted"));
                return(new NullJsonResult());
            }
            else
            {
                return(Json(new { Errors = ModelState.SerializeErrors() }));
            }
        }