public ActionResult AddItem(int? id)
        {
            if (id == null)
            {
                return View("Index");
            }

            AddOrderLineItemViewModel aolivm =
               new AddOrderLineItemViewModel
               {
                   OrderId = id.Value,
                   ProductList = new SelectList(
                       _productRepository.GetAll(),
                       "Name",
                       "Name")
               };
            return View(aolivm);
        }
        public ActionResult AddItem(int?id)
        {
            if (id == null)
            {
                return(View("Index"));
            }

            AddOrderLineItemViewModel aolivm =
                new AddOrderLineItemViewModel
            {
                OrderId     = id.Value,
                ProductList = new SelectList(
                    _productRepository.GetAll(),
                    "Name",
                    "Name")
            };

            return(View(aolivm));
        }
        public ActionResult AddItem(AddOrderLineItemViewModel aolivm)
        {
            if (ModelState.IsValid)
            {
                var product = _productRepository.Get(aolivm.ProductName);
                var order = _orderRepository.Get(aolivm.OrderId);

                order.AddOrderLineItem(product, aolivm.Quantity.Value);

                _orderRepository.Update(order);

                return RedirectToAction("OrderDetail", new { id = aolivm.OrderId });
            }
            else
            {
                aolivm.ProductList = new SelectList(
                       _productRepository.GetAll(),
                       "Name",
                       "Name");
                return View(aolivm);
            }
        }
        public ActionResult AddItem(AddOrderLineItemViewModel aolivm)
        {
            if (ModelState.IsValid)
            {
                var product = _productRepository.Get(aolivm.ProductName);
                var order   = _orderRepository.Get(aolivm.OrderId);

                order.AddOrderLineItem(product, aolivm.Quantity.Value);

                _orderRepository.Update(order);

                return(RedirectToAction("OrderDetail", new { id = aolivm.OrderId }));
            }
            else
            {
                aolivm.ProductList = new SelectList(
                    _productRepository.GetAll(),
                    "Name",
                    "Name");
                return(View(aolivm));
            }
        }