public async Task <ActionResult> Edit([Bind(Include = "ProductId,ItemId,OldProductId,OldItemId")] ProductItem productItem)
        {
            if (ModelState.IsValid)
            {
                if (await productItem.CanChangeAsync(db))
                {
                    await productItem.ChangeAsync(db);
                }

                return(RedirectToAction("Index"));
            }
            return(View(productItem));
        }