public ActionResult Edit(Manufacturer manufacturer)
 {
     if (ModelState.IsValid)
     {
         db.Entry(manufacturer).State = EntityState.Modified;
         db.SaveChanges();
         return RedirectToAction("Index");
     }
     return View(manufacturer);
 }
        public ActionResult Create(Manufacturer manufacturer)
        {
            if (ModelState.IsValid)
            {
                db.Manufacturers.Add(manufacturer);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            return View(manufacturer);
        }
        public ActionResult Create(Manufacturer manufacturer)
        {
            if (db.Manufacturers.Any(x => x.Name == manufacturer.Name))
            {
                ModelState.AddModelError("Name", "There is already a manufacturer with that name.");
            }

            if (ModelState.IsValid)
            {
                db.Manufacturers.Add(manufacturer);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            return View(manufacturer);
        }