public ActionResult Edit(EditViewModel editViewModel)
        {
            if (editViewModel == null)
            {
                throw new HttpException(400, "Bad Request");
            }

            var question = QuestionService.FindById(editViewModel.QuestionId);
            if (question == null)
            {
                throw new HttpException(404, "Not Found");
            }

            question.Content = editViewModel.Content;
            question.QuestionGroup = QuestionGroupService.FindById(editViewModel.DropDownList_QuestionGroup_Property.SelectedQuestionGroup);
            question.QuestionGroupId = editViewModel.DropDownList_QuestionGroup_Property.SelectedQuestionGroup != -1 ? (int?)editViewModel.DropDownList_QuestionGroup_Property.SelectedQuestionGroup : null;
            QuestionService.UpdateQuestion(question);
            TempData["QuestionId"] = question.QuestionId;
            TempData["QuestionName"] = question.Content;
            TempData["Message"] = QuestionsMessage.EditSuccess;
            return Redirect(Url.Content("~/feedback/questions/index"));
        }
        public ActionResult Edit(int? id)
        {
            if (id == null)
            {
                throw new HttpException(400, "Bad Request");
            }

            var question = QuestionService.FindById(id.Value);
            if (question == null)
            {
                throw new HttpException(404, "Not Found");
            }

            var dropdownlist_QuestionGroup_Property = new EditViewModel.DropDownList_QuestionGroup()
            {
                QuestionGroups = QuestionGroupService.GetQuestionGroups().ToList(),
                SelectedQuestionGroup = question.QuestionGroup != null ? question.QuestionGroup.QuestionGroupId : -1
            };

            var editViewModel = new EditViewModel()
            {
                QuestionId = question.QuestionId,
                Content = question.Content,
                DropDownList_QuestionGroup_Property = dropdownlist_QuestionGroup_Property,
            };
            return View("~/views/feedback/questions/edit.cshtml", editViewModel);
        }