问题与动态加载按钮点击用户控件 [英] Issue with dynamically loading a user control on button click

问题描述

我有一个页面中，我动态加载的用户控件如下：

I have a page in which I am loading a user control dynamically as follows:

Default.aspx的：

    <cc1:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
    </cc1:ToolkitScriptManager>

    <asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>

Default.aspx.cs：

    protected void Page_Load(object sender, EventArgs e)
    {
        var ctrl = LoadControl("~/UserCtrl1.ascx");
        ctrl.ID = "ucUserCtrl1";
        PlaceHolder1.Controls.Add(ctrl);
    }

下面是code对于 UserCtrl1.ascx

<asp:Label ID="Label1" runat="server"></asp:Label>
<asp:Button ID="Button1" runat="server" Text="Button1" OnClick="Button1_Click" />
<br />
<asp:PlaceHolder ID="PlaceHolder2" runat="server"></asp:PlaceHolder>

我动态加载另一个用户控件被点击Button1的时候

I am dynamically loading another user control when the Button1 is clicked

UserCtrl1.ascx.cs

    protected void Button1_Click(object sender, EventArgs e)
    {
        Label1.Text = "UserControl - 1 button clicked!";

        var ctrl = LoadControl("~/UserCtrl2.ascx");
        ctrl.ID = "ucUserCtrl2";
        PlaceHolder2.Controls.Add(ctrl);
    }

下面是标记为UserCtrl2.ascx

Below is the markup for UserCtrl2.ascx

<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
    <ContentTemplate>
        <asp:Label ID="Label2" runat="server"></asp:Label>
        <asp:Button ID="Button2" runat="server" Text="Button2" OnClick="Button2_Click" />
    </ContentTemplate>
</asp:UpdatePanel>

UserCtrl2.ascx.cs

    protected void Button2_Click(object sender, EventArgs e)
    {
        Label2.Text = "UserControl - 2 button clicked!";
    }

页面加载当我点击Button1的在UserCtrl1 click事件触发，我能看到Label1的文本后。这也正常加载UserCtrl2，但是当我点击Button2的在UserCtrl2 click事件dosent火，当我点击了两次的Button2从页面UserCtrl2控制dissappears更糟。我该如何解决这个问题？

After the page loads when I click the Button1 in UserCtrl1 the click event fires and I am able to see the Label1 text. It also properly loads the UserCtrl2, but when I click the Button2 in UserCtrl2 the click event dosent fire and even worse when I click the Button2 twice the UserCtrl2 control dissappears from the page. How can I fix this?

推荐答案

与第二控制的问题是，你是装载仪只按钮1.点击后，但是，当其他一些（不是按钮1点击）回传的发生第二控制未加载。

The problem with the second control is that you are loding it only after the click of button 1. But when some other (not button 1 click) postback happens your second control is not loaded.

一个可能的修复是节约一些标志（例如在ViewState中），这将有助于你确定你的第二个控制应该被加载（并加载在页面加载）。

One of possible fixes is saving some flag (e.g. in ViewState) that will help you to determine if your second control should be loaded (and load in on page load).

protected void Button1_Click(object sender, EventArgs e)
{
    Label1.Text = "UserControl - 1 button clicked!";

    var ctrl = LoadControl("~/UserCtrl2.ascx");
    ctrl.ID = "ucUserCtrl2";
    PlaceHolder2.Controls.Add(ctrl);

    this.SecondControlLoaded = true; // This flag saves to ViewState that your control was loaded.
}

protected void Page_Load(object sender, EventArgs e)
{
    var ctrl = LoadControl("~/UserCtrl1.ascx");
    ctrl.ID = "ucUserCtrl1";
    PlaceHolder1.Controls.Add(ctrl);

    if (this.SecondControlLoaded)
    {
        var ctrl = LoadControl("~/UserCtrl2.ascx");
        ctrl.ID = "ucUserCtrl2";
        PlaceHolder2.Controls.Add(ctrl);
    }
}

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