ASP.NET的DropDownList OnSelectedIndexChanged事件不会触发 [英] ASP.NET DropDownList OnSelectedIndexChanged event not fired

问题描述

我试图用一些AJAX和ASP.Net在一起，使我不必刷新整个页面运行的功能，但我已经跨越一个问题，在做这个迷迷糊糊

I'm trying to use some AJAX and ASP.Net together to enable me to run functions without having to refresh the whole page but i've stumbled across a problem in doing this

下面是我的code

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <asp:DropDownList ID="ddl1" runat="server" OnSelectedIndexChanged="update1" />

        <asp:TextBox runat="server" ID="txt1" />

    </ContentTemplate>
</asp:UpdatePanel>

这是我的code后面

And here's my code behind

 Sub update1(ByVal sender As Object, ByVal e As EventArgs)

    txt1.Text = Now.ToString

End Sub

本次活动不火，因为我没有的AutoPostBack =真在我的DDL，但补充说，到DDL将回发整个页面。

The event doesn't fire because I don't have AutoPostBack="True" on my ddl but adding that to the ddl will postback the whole page.

有没有办法避免使用的AutoPostBack =真，使其只更新面板？

Is there a way to avoid using AutoPostBack="True" so that it only updates the panel?

我知道我可以使用 ASP：按钮来解决这个问题，但我真的很想能够使用一个DDL与 OnSelectedIndexChanged

I know I can use an asp:Button to get around this but i'd really like to be able to use a ddl with OnSelectedIndexChanged

感谢

推荐答案

如果你想避免整个视图状态发送给服务器，你应该看看的回调。

If you want to avoid to send the whole viewstate to the server, you should look at callbacks.

相反，如果你想避免整个页面的刷新，但回发，这应该工作：

Instead, if you want to avoid a refresh of the entire page, but with postback, this should work:

<asp:DropDownList ID="ddl1" runat="server" OnSelectedIndexChanged="update1" AutoPostBack="True"  />

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <Triggers>
         <asp:AsyncPostbackTrigger ControlID="ddl1" EventName="SelectedIndexChanged" />
    </Triggers>
    <ContentTemplate>
        <asp:TextBox runat="server" ID="txt1" />
    </ContentTemplate>
</asp:UpdatePanel>

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