c# - 购物车问题，asp.net c#

Question

我构建了一个简单的购物车。问题是我第一次尝试添加项目时没有任何反应。如果我第二次单击购买按钮，则会添加一个项目。 如果出现这个问题是什么原因？

谢谢!

.aspx

<asp:Content ContentPlaceHolderID="main" runat="server">
White lily
<asp:Button ID="button" runat="server" OnClick="buy_Click" />
</asp:Content>

<asp:Content ContentPlaceHolderID="rightBar" runat="server">
    <UserControl:ShoppingCart id="shoppingCart" runat="server" />
</asp:Content>

.ascx

public partial class UserControls_ShoppingCart : System.Web.UI.UserControl
{
    private List<Flower> FlowerList 
    {
        get
        {
            List<Flower> tmp = Session["FlowerList"] as List<Flower>;
            if (tmp == null)
            {
                tmp = new List<Flower>();
            }
            return tmp;
        }
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            FillRepeater();
        }

    }

    public void ShoppingCart_ItemDataBound(object sender, RepeaterItemEventArgs e)
    {
        if (e.Item != null)
        {
            Label itemLabel = e.Item.FindControl("itemLabel") as Label;
            Flower flower = e.Item.DataItem as Flower;
            if (flower != null)
            {
                itemLabel.Text = flower.getName(flower);
            }
        }
    }

    private void FillRepeater()
    {
        shoppingCartRepeater.DataSource = FlowerList;
        shoppingCartRepeater.DataBind();
    }

    public void AddFlower(Flower flower)
    {
        FlowerList.Add(flower);
        Session["FlowerList"] = FlowerList;
        FillRepeater();
    }
}

Answer 1

根据我对第一个答案的评论..试试这个

 private List<Flower> FlowerList 
    {
        get
        {
             return(_FlowerList);
        }
        set
        {
            _FlowerList = value;
        }

    }
    protected List<Flower> _FlowerList = new FlowerList();
    protected void Page_Load(object sender, EventArgs e)
    {
       if (Session["FlowerList"]!= null) {
           FlowerList = (List<Flower>)Session["FlowerList"];
       }
        if (!Page.IsPostBack)
        {
            FillRepeater();
        }
    }

它应该与其他一切一样工作。更好的方法是使用 ViewState，并将 _FlowerList 的值保存在 SaveViewState() 中