DropDown没有触发OnSelectedIndexChanged

Question

我有一个带下拉列表的页面

   <asp:Content runat="server" ContentPlaceHolderID="ContentPlaceHolder1">
  <asp:DropDownList ID="DropDownList1" runat="server" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
    <asp:ListItem>Cellsite</asp:ListItem>
    <asp:ListItem>Agreement</asp:ListItem>
    <asp:ListItem>Event</asp:ListItem>
    <asp:ListItem>User</asp:ListItem>
</asp:DropDownList>
<asp:Label runat="server" ID="EntityName"></asp:Label>
<ig:WebScriptManager ID="WebScriptManager1" runat="server"></ig:WebScriptManager>
<ig:WebDataGrid ID="EntityGrid" runat="server"  Width="100%">
    <Behaviors>
        <ig:Sorting>
        </ig:Sorting>
    </Behaviors>
</ig:WebDataGrid>

代码背后是

     protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        EntityName.Text = DropDownList1.SelectedItem.Text;
    }

对于某些原因，标签永远不会更新，selectindexchanged的事件根本不会触发我需要在此事件中添加动态网格。 任何线索？

Answer 1

您需要在下拉列表中添加AutoPostBack

 <asp:DropDownList ID="DropDownList1" runat="server" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged" AutoPostBack="true">

实际上，当您没有AutoPostBack = true属性时，您可以确定没有回发帖子。

Answer 2

set dropdownlist属性AutoPostBack =“true”

    <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
    <asp:ListItem>Cellsite</asp:ListItem>
    <asp:ListItem>Agreement</asp:ListItem>
     <asp:ListItem>Event</asp:ListItem>
     <asp:ListItem>User</asp:ListItem>
     </asp:DropDownList>