Inheritance: ProductAdd
        public ActionResult Edit(int id, ProductBase newItem)
        {
            if (ModelState.IsValid)
            {
                // Configure some of its values
                newItem.DateOfMostRecentUpdate = DateTime.Now;

                // Save to session state
                Session["product"] = newItem;

                // Show its details
                return(RedirectToAction("details", new { id = newItem.Id }));
            }
            else
            {
                return(View(newItem));
            }
        }
        public ActionResult Edit(int id, ProductBase newItem)
        {
            if (ModelState.IsValid)
            {
                // Configure some of its values
                newItem.DateOfMostRecentUpdate = DateTime.Now;

                // Save to session state
                Session["product"] = newItem;

                // Show its details
                return RedirectToAction("details", new { id = newItem.Id });
            }
            else
            {
                return View(newItem);
            }
        }