public ActionResult Edit(Product product)
 {
     LoadCategories();
     if (ModelState.IsValid)
     {
         DataProvider.Entry(product).State = EntityState.Modified;
         DataProvider.Commit();
         return RedirectToAction("Index");
     }
     return View(product);
 }
 public ActionResult Create(Product product)
 {
     LoadCategories();
     if (ModelState.IsValid)
     {
         DataProvider.Add(product);
         DataProvider.Commit();
         return RedirectToAction("Index");
     }
     return View(product);
 }