如何在网页表单中加载页面之前填充下拉列表? [英] How to populate dropdown list before page loads in webforms?

问题描述

我的控件 (System.Web.UI.UserControl) 中有以下 Page_Load 方法:

I have the following Page_Load method in my control (System.Web.UI.UserControl):

protected void Page_Load(object sender, EventArgs e)
{
    DropDownList ShowAssumptions = new DropDownList();
    List<string> list = new List<string>()
    {
        "test",
        "test2"
    };
    ShowAssumptions.DataSource = from i in list
                                 select new ListItem()
                                 {
                                     Text = i,
                                     Value = i
                                 };
    ShowAssumptions.DataBind();
}

然后，在我的 .aspx 中，我有这个:

Then, in my .aspx I have this:

<asp:DropDownList id="ShowAssumptions" runat="server">
</asp:DropDownList>

但是，DropDownList 永远不会被填充.我做错了什么?

But, the DropDownList never gets populated. What am I doing wrong?

推荐答案

只需将列表指定为数据源即可.此外，我假设您不想在每次回发时重新加载列表.

Just assign the list as the datasource. Also I assume you don't want to reload the list on every PostBack.

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
         List<string> list = new List<string>()
         {
            "test",
            "test2"
         };
        ShowAssumptions.DataSource = list;
        ShowAssumptions.DataBind();
    }
}

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