小编blu*_*xth的帖子

我正在尝试使用购物车测试 WCF Web 服务。下面的方法基本上接收 CartLine 列表，并从数据库中减去添加到购物车的所有产品。然后，它发送一条已处理消息，或者如果库存不足则发送一条订单取消消息。

public string Deliver(List<CartLine> cartLine)\n        {\n            string strOut = null;\n            StartPurchase();\n\n            if (Convert.ToBoolean(HttpContext.Current.Session["TransactionStarted"]))\n            {\n                //Traverse the cart line\n                for (int i = 0; i < cartLine.Count; i++)\n                {\n                    //for each product in the cart line decrease inventory\n                    if (cartLine[i].Product.Stock > 0)\n                    {\n                        //here decreasing inventory\n                        (cartLine[i].Product.Stock) -= (cartLine[i].Quantity);\n\n                             //Advice that entity has changed\n                            db.Entry(cartLine[i].Product).State = EntityState.Modified; //offending line\n                            db.SaveChanges();\n\n                       strOut = "Order Processed!";\n                    }\n                    else\n                    {\n                       strOut =  "Order cancelled, Stock missing!";\n\n                    }\n                }\n\n …