public ActionResult NewTopic(TopicVM vm)
        {
            if (repo.GetById(vm.ClassId) == null)
            {
                return(HttpNotFound());
            }


            if (ModelState.IsValid)
            {
                var top = new ClassTopic
                {
                    Topic   = vm.Topic,
                    ClassId = vm.ClassId,
                    Order   = vm.Order
                };

                _db.ClassTopic.Add(top);
                _db.SaveChanges();

                return(PartialView("PartialAllClassTopics", GetAllTopics(top.ClassId)));
            }

            return(PartialView("PartialClassTopic", vm));
        }
        public static ClassTopic ToEntity(ViewClassTopic model)
        {
            ClassTopic item = new ClassTopic();

            item.Id         = model.Id;
            item.ClassID    = model.ClassID;
            item.TopicID    = model.TopicID;
            item.IsDeleted  = model.IsDeleted;
            item.CreateTime = model.CreateTime;



            return(item);
        }
        public static ViewClassTopic ToViewModel(ClassTopic model)
        {
            if (model == null)
            {
                return(null);
            }

            ViewClassTopic item = new ViewClassTopic();


            item.Id         = model.Id;
            item.ClassID    = model.ClassID;
            item.TopicID    = model.TopicID;
            item.IsDeleted  = model.IsDeleted;
            item.CreateTime = model.CreateTime;


            return(item);
        }