public ActionResult Edit(long? id)
        {
            EditCategoryViewModel view = new EditCategoryViewModel
            {
                Category = _service.GetCategory(id ?? 0)
            };

            return View(view);
        }
        public ActionResult Create()
        {
            EditCategoryViewModel view = new EditCategoryViewModel
            {
                Category = new CategoryModel()
            };

            return View("edit", view);
        }
        public ActionResult Edit(CategoryModel model)
        {
            if(ModelState.IsValid)
            {
                long id = _service.SaveCategory(model);

                return RedirectToAction("view", "category", new
                {
                    id = id
                });
            }

            EditCategoryViewModel view = new EditCategoryViewModel
            {
                Category = model
            };

            return View(view);
        }