dropdwnlist autopostback不工作

Question

dropdwnlist autopostback不能按如下方式运行我的代码：

<asp:DropDownList ID="ddlState" runat="server" Width="200px" AutoPostBack="true" onselectedindexchanged="ddlState_SelectedIndexChanged" >
   <%--  <asp:ListItem Selected="True">--Select--</asp:ListItem>--%>
</asp:DropDownList>

代码的背后是：

protected void ddlState_SelectedIndexChanged(object sender, EventArgs e)
{
    ddlDistrict.Enabled = true;
    ddlTaluka.Enabled = true;
    DataTable dtObj = new DataTable();
    using (var client = ServiceClient<IPallaviAddressManager>.Create("PallaviAddressManager"))
    {
        dtObj = client.Instance.GetAllStates();
    }
    var result = (from dt in dtObj.AsEnumerable()
                      where dt.Field<Int64>("StateID") == Convert.ToInt64(ddlState.SelectedValue)
                      select dt);
    dtObj = result.CopyToDataTable();
    ddlDistrict.DataSource = dtObj;
    ddlState.DataTextField = "Description";
    ddlState.DataValueField = "DistrictID";
}

你能帮上忙吗？

Answer 1

将其设置为runat="server"和autopostback="true"

Answer 2

尝试按照影子向导的建议，在代码末尾添加ddlDistrict.DataBind()；

Answer 3

听起来这件事并没有很好地联系起来。

尝试在设计器中选择DropDownList控件，转到属性选项卡并双击SelectedIndexChanged事件右侧的空间，如果它在代码隐藏中创建了一个新的存根，则说明原始事件没有正确挂钩。