UpdatePanel AsyncPostbackTrigger 未触发

Question

我遇到了一些小问题，如有任何帮助，我们将不胜感激。

情况是这样的：

<asp:UpdatePanel ID="UP_Panel" runat="server" UpdateMode="Conditional">
    <ContentTemplate>
        <asp:DropDownList ID="ddlSwitch" runat="server" Width="250px" AutoPostback="true"
            OnSelectedIndexChanged="ddlSwitch_SelectedIndexChanged">

            <asp:ListItem Value="continent" Text="Continent"></asp:ListItem>
            <asp:ListItem Value="region" Text="Region"></asp:ListItem>
            <asp:ListItem Value="country" Text="Country"></asp:ListItem>

        </asp:DropDownList>

        <asp:UpdatePanel ID="UP_Switch" runat="server" UpdateMode="Conditional">
            <ContentTemplate>
                // Some content
            </ContentTemplate>
            <Triggers>
                <asp:AsyncPostBackTrigger ControlID="ddlSwitch" EventName="SelectedIndexChanged" />
            </Triggers>
        </asp:UpdatePanel>
    </ContentTemplate>
</asp:UpdatePanel>

当ddlSwitch选择的索引改变时我想更新UP_Switch里面的内容，但是SelectedIndexChanged事件没有好像火了我做错了什么？

提前致谢！

Answer 1

我刚刚测试了您的代码，似乎正在使用一些测试修改：ASPX

<asp:UpdatePanel ID="UP_Panel" runat="server" UpdateMode="Conditional">
    <ContentTemplate>
        <asp:DropDownList ID="ddlSwitch" runat="server" Width="250px" AutoPostback="true"
            OnSelectedIndexChanged="ddlSwitch_SelectedIndexChanged">

            <asp:ListItem Value="continent" Text="Continent"></asp:ListItem>
            <asp:ListItem Value="region" Text="Region"></asp:ListItem>
            <asp:ListItem Value="country" Text="Country"></asp:ListItem>

        </asp:DropDownList>

        <asp:UpdatePanel ID="UP_Switch" runat="server" UpdateMode="Conditional">
            <ContentTemplate>
                <asp:Literal ID="litUpSwitch" runat="server"></asp:Literal>
            </ContentTemplate>
            <Triggers>
                <asp:AsyncPostBackTrigger ControlID="ddlSwitch" EventName="SelectedIndexChanged" />
            </Triggers>
        </asp:UpdatePanel>
    </ContentTemplate>
</asp:UpdatePanel>

ddlSwitch_SelectedIndexChanged 的隐藏代码：

protected void ddlSwitch_SelectedIndexChanged(object sender, EventArgs e)
{
    litUpSwitch.Text = "DDL Switch go activated";
}

结果：

UpdatePanel AsyncPostbackTrigger 未触发

UpdatePanel AsyncPostbackTrigger not firing

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