public ActionResult EditSlide(int id, EditSlide model)
 {
     if(!ModelState.IsValid)
     {
         return View(model);
     }
     slideService.UpdateSlide(id, new Slide { Name = model.Name });
     return RedirectToAction("Index");
 } 
 public ActionResult EditSlide(int? id)
 {
     if(id == null)
     {
         return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
     }
     Slide slide = slideService.GetSlideById(id);
     if(slide == null)
     {
         return HttpNotFound();
     }
     EditSlide model = new EditSlide()
     { Name = slide.Name, Path = slide.Path };
     return View(model);
 }