public ActionResult Update(ManufacturerViewModel model)
        {
            if (ModelState.IsValid)
            {
                bool isNotExist = _manufacturersRepository.FindDuplicateByNameAndId(model.Name, model.Id);

                if (isNotExist)
                {
                    var manufacturer = _manufacturersRepository.Get(model.Id);
                    manufacturer.Update(model.Name);

                    try
                    {
                        _manufacturersRepository.Update(manufacturer);
                        TempData["success"] = String.Format("Edycja producenta {0} wykonana pomyślnie",
                            manufacturer.Name);
                        return RedirectToAction("List");
                    }
                    catch (Exception)
                    {
                        TempData["error"] = "Wystąpił problem z połączeniem do bazy danych.";
                        return RedirectToAction("Update", new {@id = model.Id});
                    }
                }
                TempData["error"] = String.Format("Producent o nazwie {0} już istnieje", model.Name);
            }
            else
            {
                TempData["error"] = "Nazwa producenta jest wymagana";
            }

            return RedirectToAction("Update", new {@id = @model.Id});
        }
        public ActionResult Update(int id)
        {
            var manufacturer = _manufacturersRepository.Get(id);
            if (manufacturer == null) return RedirectToAction("List", "ManageManufacturers");

            var categoryModel = new ManufacturerViewModel
            {
                Name = manufacturer.Name,
                Id = manufacturer.ID
            };

            return View(categoryModel);
        }