public ActionResult Create(Product product)
        {
            if (ModelState.IsValid)
            {
                db.Products.Add(product);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            ViewBag.CategoryID = new SelectList(db.Categories, "CategoryID", "CategoryName", product.CategoryID);
            ViewBag.CompanyID = new SelectList(db.Companies, "CompanyID", "CompanyName", product.CompanyID);
            return View(product);
        }
 public ActionResult Edit(Product product)
 {
     if (ModelState.IsValid)
     {
         db.Entry(product).State = EntityState.Modified;
         db.SaveChanges();
         return RedirectToAction("Index");
     }
     ViewBag.CategoryID = new SelectList(db.Categories, "CategoryID", "CategoryName", product.CategoryID);
     ViewBag.CompanyID = new SelectList(db.Companies, "CompanyID", "CompanyName", product.CompanyID);
     return View(product);
 }