为什么当控件没有进行完整的回发时动态创建的用户控件会消失? [英] Why dynamically created user controls disappear when controls are not doing full postbacks?
问题描述
根据我目前的理解，当您拥有 UpdatePanel 控件时，没有完整的回发.因此，如果我动态添加自定义用户控件并且它们的代码中更新了 UpdatePanel，它们不应该从它们加载到的页面中消失，对吗?显然不是.我做了一个简单的项目来测试，但我的动态控件在单击时仍然消失，即使它们不应该触发完整的回发.我有一个加载控件的 aspx 页面:
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="TESTmultipleScriptManagerControls.aspx.cs" Inherits="myPlayground.TESTmultipleScriptManagerControls" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 过渡//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head runat="服务器"><标题></标题></头><身体><form id="form1" runat="server"><asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager><asp:UpdatePanel ID="UpdatePanel1" runat="server"><内容模板><asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click"/><asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder></内容模板></asp:UpdatePanel></div></表格></身体></html>后面有以下代码:
protected void Button1_Click(object sender, EventArgs e){TESTcontrol1 temp = LoadControl("TESTcontrol1.ascx") as TESTcontrol1;PlaceHolder1.Controls.Add(temp);TESTcontrol1 temp2 = LoadControl("TESTcontrol1.ascx") as TESTcontrol1;PlaceHolder1.Controls.Add(temp2);}
还有一个简单的用户控件:
<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="TESTcontrol1.ascx.cs" Inherits="myPlayground.TESTcontrol1" %><asp:ScriptManagerProxy ID="ScriptManagerProxy1" runat="server"></asp:ScriptManagerProxy><asp:UpdatePanel ID="UpdatePanel1" runat="server"><内容模板><asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click"/><asp:Label ID="Label1" runat="server" Text="Label"></asp:Label></内容模板></asp:UpdatePanel>
后面有以下代码:
protected void Button1_Click(object sender, EventArgs e){Label1.Text = System.DateTime.Now.ToString();}
关于为什么控件消失的任何想法，即使不应该触发回发?
解决方案 根据我目前的理解，当你有一个 UpdatePanel控制没有完整的回发.
从 UpdatePanel 触发的回发始终执行整个页面的生命周期.所有事件都正常触发.是否使用 UpdatePanel 没有区别.每次以编程方式添加控件时，您都需要在每次回发时重新添加它.
阅读这篇文章，它可能会帮助您更好地了解这里发生了什么.
Based on my current understandings, when you have an UpdatePanel control there is no full postback. Therefore if I dynamically add custom user controls and they have UpdatePanels that are updated in their code they shouldnt disappear from the page they are loaded into, right? Apparently not. I made a simple project to test and still my dynamic controls disappear when clicked even though they should not be triggering a full postback. I have an aspx page that loads the controls:
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="TESTmultipleScriptManagerControls.aspx.cs" Inherits="myPlayground.TESTmultipleScriptManagerControls" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
<asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>
</ContentTemplate>
</asp:UpdatePanel>
</div>
</form>
</body>
</html>
With the following code behind:
protected void Button1_Click(object sender, EventArgs e)
{
TESTcontrol1 temp = LoadControl("TESTcontrol1.ascx") as TESTcontrol1;
PlaceHolder1.Controls.Add(temp);
TESTcontrol1 temp2 = LoadControl("TESTcontrol1.ascx") as TESTcontrol1;
PlaceHolder1.Controls.Add(temp2);
}
And a simple user control:
<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="TESTcontrol1.ascx.cs" Inherits="myPlayground.TESTcontrol1" %>
<asp:ScriptManagerProxy ID="ScriptManagerProxy1" runat="server">
</asp:ScriptManagerProxy>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
With the following code behind:
protected void Button1_Click(object sender, EventArgs e)
{
Label1.Text = System.DateTime.Now.ToString();
}
Any ideas on why the controls are disappearing even though there shouldnt be a postback triggering?
解决方案
OK based on my current understandings, when you have an UpdatePanel
control there is no full postback.
Postbacks triggered from UpdatePanels always execute the full page life-cycle. All the events are triggered normally. It makes no difference whether you use an UpdatePanel or not. Every time you add a control programmatically you need to re-add it on every postback.
Read this post, it may help you understand a bit better what's going on here.
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