protected void AddToCartButton_Click(object sender, EventArgs e)
        {
            using (ToyStoreEntities context = new ToyStoreEntities())
            {
                String CurrentUserName = ((Site1)Page.Master).CurrentUserName;
                Cart myCart;
                //找到该用户的购物车
                var query = from p in context.Carts
                            where p.UserName == CurrentUserName
                            select p;
                if (query.Count() == 0)
                {
                    myCart = new Cart();
                    myCart.UserName = CurrentUserName;
                    context.AddToCarts(myCart);
                }
                else
                {
                    myCart = query.First();
                }
                //查找是否已有该购物车明细
                var query1 = from p in myCart.CartDetails
                             where p.Product.Id == CurrentProduct.Id
                             select p;
                CartDetail myCartDetail;
                if (query1.Count() == 0)
                {
                    //如果没有,新增
                    myCartDetail = new CartDetail();
                    myCartDetail.Cart = myCart;
                    myCartDetail.ProductId = CurrentProduct.Id;
                    myCartDetail.OTY = 1;

                }
                else
                {
                    //如果有,修改数量
                    myCartDetail = query1.First();
                    myCartDetail.OTY += 1;
                }
                context.SaveChanges();
            }
        }
 /// <summary>
 /// Create a new Cart object.
 /// </summary>
 /// <param name="id">Initial value of the Id property.</param>
 /// <param name="userName">Initial value of the UserName property.</param>
 public static Cart CreateCart(global::System.Int32 id, global::System.String userName)
 {
     Cart cart = new Cart();
     cart.Id = id;
     cart.UserName = userName;
     return cart;
 }
 /// <summary>
 /// Deprecated Method for adding a new object to the Carts EntitySet. Consider using the .Add method of the associated ObjectSet&lt;T&gt; property instead.
 /// </summary>
 public void AddToCarts(Cart cart)
 {
     base.AddObject("Carts", cart);
 }