UserControl 中嵌套控件的 FindControl 返回 null
我有一个非常奇怪的问题。我有一个 UserControl，里面有一些控件。我想在另一个回发中引用这些控件。但是当我尝试获取它们时，控件的 Controls 属性返回 null。 我正在使用vs2008。
下面是示例代码：
public partial class MyUserControl : System.Web.UI.UserControl, INamingContainer
{
protected void Page_Load(object sender, EventArgs e)
{
foreach (Control control in this.Controls)
{
Response.Write(control.ClientID);
}
}
private void MyTable()
{
Table table = new Table();
TableRow row = new TableRow();
TableCell cell = new TableCell();
CheckBox check = new CheckBox();
check.ID = "theId";
check.Text = "My Check";
check.AutoPostBack = true;
cell.Controls.Add(check);
row.Cells.Add(cell);
check = new CheckBox();
check.ID = "theOther";
check.AutoPostBack = true;
check.Text = "My Other Check";
cell = new TableCell();
cell.Controls.Add(check);
row.Cells.Add(cell);
table.Rows.Add(row);
this.Controls.Add(table);
}
protected override void Render(HtmlTextWriter writer)
{
MyTable();
base.Render(writer);
}
}
Default.aspx 页面类似于：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.cs" Inherits="Tester.Default" %>
<%@ Register TagPrefix="uc1" TagName="MyControl" Src="~/MyUserControl.ascx" %>
<!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>Unbenannte Seite</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<uc1:MyControl ID="MyControlInstance" runat="server" />
</div>
</form>
</body>
</html>
我不知道我是否迷失在 ASP.NET 生命周期的某些部分中。但这种情况让我抓狂。任何帮助将非常感激。
I have a very weird issue. I have a UserControl that has some controls inside. I want to refer those controls after, in another postback. But when I try to get them the Controls property of my controls returns null.
I'm working on vs2008.
Here is the sample code:
public partial class MyUserControl : System.Web.UI.UserControl, INamingContainer
{
protected void Page_Load(object sender, EventArgs e)
{
foreach (Control control in this.Controls)
{
Response.Write(control.ClientID);
}
}
private void MyTable()
{
Table table = new Table();
TableRow row = new TableRow();
TableCell cell = new TableCell();
CheckBox check = new CheckBox();
check.ID = "theId";
check.Text = "My Check";
check.AutoPostBack = true;
cell.Controls.Add(check);
row.Cells.Add(cell);
check = new CheckBox();
check.ID = "theOther";
check.AutoPostBack = true;
check.Text = "My Other Check";
cell = new TableCell();
cell.Controls.Add(check);
row.Cells.Add(cell);
table.Rows.Add(row);
this.Controls.Add(table);
}
protected override void Render(HtmlTextWriter writer)
{
MyTable();
base.Render(writer);
}
}
and the Default.aspx page is something like:
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.cs" Inherits="Tester.Default" %>
<%@ Register TagPrefix="uc1" TagName="MyControl" Src="~/MyUserControl.ascx" %>
<!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>Unbenannte Seite</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<uc1:MyControl ID="MyControlInstance" runat="server" />
</div>
</form>
</body>
</html>
I don't know if I'm lost in some part of the ASP.NET life cycle. But this situation is making me crazy. Any help would be very grateful.
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评论（2）
在
CreateChildControls或OnInit中创建子控件 (MyTable)：或者
您不应该/不能在
Render中创建控件code> 发生在Page_Load之后。请参阅此处了解 ASP.Net 页面生命周期。Create your child controls (
MyTable) in eitherCreateChildControlsorOnInit:Or
You shouldn't/cannot create controls in
Renderas it occurs afterPage_Load. See the ASP.Net Page Lifecycle here.我相信这是因为
Render事件发生在Page_Load之后，因此当您尝试迭代控件集合时，它尚未设置。最常见的解决方案是重写 CreateChildControls 以获得正确的计时。I believe it is because the
Renderevent occurs afterPage_Load, so when you are trying to iterate your control collection, it hasn't been set up yet. Most common solution is to overrideCreateChildControlsto get the proper timing down.