添加到“自定义控件”时触发UpdatePanel消失
[英]Trigger for UpdatePanel disappearing when added to a “custom control”
问题描述
Basically, in a nutshell, the problem is that dynamically generated triggers for an UpdatePanel can no longer be found (by ASP.NET) as soon as I add them as children of a custom control. 
简而言之，问题在于，一旦我将它们添加为自定义控件的子级，就不再能够（通过ASP.NET）找到动态生成的UpdatePanel触发器。
Since the amount of code I'm working on is quite substantial I've recreated the problem on a smaller scale, which will make it easier to debug. 由于我正在处理的代码量很大，因此我以较小的规模重新创建了该问题，这将使调试更加容易。
The error thrown in my face is: 我脸上的错误是：
A control with ID 'theTrigger' could not be found for the trigger in UpdatePanel 'updatePanel'.
I'm not sure whether this implementation of a "custom control" is the right way to go about it, but I did not write the original implementation: I'm working with code written by a previous developer to which I cannot make large modifications. 我不确定这种“自定义控件”的实现是否正确，但是我没有编写原始的实现：我正在使用以前的开发人员编写的代码，无法对其进行大量修改。 It looks a little unusual to me, but, alas, this is what I've been given. 在我看来，这有点不寻常，但是，las，这就是我得到的。
Default.aspx Default.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="TestWeb.Default" %>
<!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:Panel runat="server" ID="panel">
</asp:Panel>
<asp:ScriptManager ID="scriptManager" runat="server"></asp:ScriptManager>
<asp:UpdatePanel runat="server" ID="updatePanel" UpdateMode="Conditional">
<ContentTemplate>
<asp:Label ID="lblSomething" runat="server"></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
</div>
</form>
</body>
</html>
Default.aspx.cs Default.aspx.cs
using System;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace TestWeb
{
public partial class Default : Page
{
protected void Page_Load(object sender, EventArgs e)
{
UselessTableWrapper table = new UselessTableWrapper();
TableRow tr = new TableRow();
TableCell td = new TableCell();
LinkButton button1 = new LinkButton { ID = "theTrigger", Text = "Click Me" };
button1.Click += button1_Click;
td.Controls.Add(button1);
tr.Controls.Add(td);
table.AddRow(tr);
panel.Controls.Add(table);
// ### uncomment these lines (and comment the one above) to see it working
// ### without the custom control
/*
Table realTable = new Table();
realTable.Controls.Add(tr);
panel.Controls.Add(realTable);
*/
updatePanel.Triggers.Add(new AsyncPostBackTrigger { ControlID = "theTrigger", EventName = "Click" });
scriptManager.RegisterAsyncPostBackControl(button1);
}
protected void button1_Click(object sender, EventArgs e)
{
lblSomething.Text = "Random number: " + new Random().Next(100);
updatePanel.Update();
}
}
}
MyControl.cs MyControl.cs
using System;
using System.Web.UI.WebControls;
namespace TestWeb
{
public class UselessTableWrapper : WebControl
{
private Table table = new Table();
protected override void OnPreRender(EventArgs e)
{
Controls.Add(table);
}
public void AddRow(TableRow row)
{
table.Controls.Add(row);
}
}
}
Any ideas would be greatly appreciated. 任何想法将不胜感激。
Edit 编辑
I've tried switching the OnPreRender event for this (found in a tutorial): 我尝试为此切换OnPreRender事件（在教程中找到）：
protected override void RenderContents(HtmlTextWriter writer)
{
writer.BeginRender();
table.RenderControl(writer);
writer.EndRender();
base.RenderContents(writer);
}
... hoping that it would fix it, but it does not. ...希望能解决它，但不能解决。
1 个解决方案
解决方案1
1 2011-04-21 11:36:14
this is the approach that I've taken with loading a ascx web control inside an aspx control from the code behind. 这是我从后面的代码在aspx控件中加载一个ascx Web控件时采用的方法。
In the control: 在控件中：
namespace dk_admin_site.Calculations
{
public partial class AssignedFieldCalculation : System.Web.UI.UserControl
{
public static AssignedFieldCalculation LoadControl(Calculation initialData)
{
var myControl = (AssignedFieldCalculation) ((Page) HttpContext.Current.Handler).LoadControl(@"~\\Calculations\AssignedFieldCalculation.ascx");
myControl._initialData = initialData;
return myControl;
}
private Calculation _initialData;
public Calculation Data { get { return _initialData; } }
protected void Page_Load(object sender, EventArgs e) {}
}
}
in the web form code behind: 在后面的网络表单代码中：
protected void Page_Load(object sender, EventArgs e)
{
if (this.IsPostBack)
{
if (ScriptManager1.AsyncPostBackSourceElementID.StartsWith("ctl00$MainContent$calc") && ScriptManager1.AsyncPostBackSourceElementID.EndsWith("$btnRemoveCalculationFromField"))
{
//do something on the postback
}
else if (ScriptManager1.AsyncPostBackSourceElementID.StartsWith("ctl00$MainContent$calc") && (ScriptManager1.AsyncPostBackSourceElementID.EndsWith("$btnMoveCalculationUp") || ScriptManager1.AsyncPostBackSourceElementID.EndsWith("$btnMoveCalculationDown")))
{
//do something on the postback
}
}
foreach (Calculation calc in calculationCollection)
{
AssignedFieldCalculation asCalc = AssignedFieldCalculation.LoadControl(calc);
asCalc.ID = "calc" + calc.UniqueXKey;
pnlFieldCalculations.Controls.Add(asCalc);
foreach (Control ct in asCalc.Controls)
{
if (ct.ID == "btnMoveCalculationDown" || ct.ID == "btnMoveCalculationUp" || ct.ID == "btnRemoveCalculationFromField")
{
ScriptManager1.RegisterAsyncPostBackControl(ct);
}
}
}
}
A few things to note: 注意事项：
You need to make each control ID unique when adding it to the asp:Panel (called pnlFieldCalculations). 将每个控件ID添加到asp：Panel（称为pnlFieldCalculations）时，需要使其唯一。 The LoadControl method allows you to pass initial arguments LoadControl方法允许您传递初始参数
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