ASP.Net c＃tailspin spyworks我的购物车类

Question

我正在研究mircosoft asp网站上的asp.net tailspin spyworks教程，当我在最后提交订单时，我收到了try catch块的错误，只是想知道是否有人可以帮助我，这是下面的错误 TAILSPIN SPYWORKS TRY CATCH ERROR

      public bool SubmitOrder(string UserName)
        {
            using (CommerceEntities1 db = new CommerceEntities1())
            {
                try
                {
                    //----------------------------------------------------------------+
                    // Add New Order Record |
                    //----------------------------------------------------------------+
                    Order newOrder = new Order();

                    newOrder.CustomerName = UserName;
                    newOrder.OrderDate = DateTime.Now;
                    newOrder.ShipDate = CalculateShipDate();
                    db.Orders.Add(newOrder);
                    db.SaveChanges();
                    //----------------------------------------------------------------+
                    // Create a new OderDetail Record for each item in the Shopping                  
                    String cartId = GetShoppingCartId();
                    var myCart = (from c in db.ViewCarts where c.CartID == cartId select c);
                    foreach (ViewCart item in myCart)
                    {
                        int i = 0;
                        if (i < 1)
                        {
                            OrderDetail od = new OrderDetail();
                            od.OrderID = newOrder.OrderID;
                            od.ProductID = item.ProductID;
                            od.Quantity = item.Quantity;
                            od.UnitCost = item.UnitCost;
                            db.OrderDetails.Add(od);
                            i++;
                        }
                        var myItem = (from c in db.ShoppingCarts
                                      where c.CartID == item.CartID &&
                                          c.ProductID == item.ProductID
                                      select c).FirstOrDefault();
                        if (myItem != null)
                        {
                            db.DeleteObject(myItem);
                        }
                    }
                    db.SaveChanges();
                }
                catch (Exception exp)
                {
                    throw new Exception("ERROR: Unable to Submit Order - " + exp.Message.ToString(),
                    exp);

                }
            }
            return (true);
        }

用户代码

未处理异常

  

错误：无法提交订单 - 方法或操作不是   实现。