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

            var trip = TripService.FindById(editViewModel.TripId);
            if (trip == null)
            {
                throw new HttpException(404, "Not Found");
            }

            trip.Name = editViewModel.Name;
            trip.Description = editViewModel.Description;
            trip.NumberOfDay = editViewModel.NumberOfDay.Value;
            trip.TripCode = editViewModel.TripCode;
            TripService.UpdateTrip(trip);

            TempData["TripId"] = trip.TripId;
            TempData["TripName"] = trip.Name;
            TempData["Message"] = TripsMessage.EditSuccess;
            return RedirectToAction("index", "trips");
        }
        public ActionResult Edit(int? id)
        {
            if (id == null)
            {
                throw new HttpException(400, "Bad Request");
            }

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

            var editViewModel = new EditViewModel()
            {
                TripId = trip.TripId,
                Name = trip.Name,
                Description = trip.Description,
                NumberOfDay = trip.NumberOfDay,
                TripCode = trip.TripCode
            };
            return View(editViewModel);
        }