动态添加子控件的错误ClientID [英] Wrong ClientID for dynamically added child control

问题描述

我正在尝试将带有.ascx标记的asp.net用户控件重做为WebControl(仅.cs).

I am trying to rework asp.net usercontrol with .ascx markup to WebControl(only .cs).

在my_new_webcontrol.cs中，我有:

In my_new_webcontrol.cs I have:

private readonly DropDownList _source = new DropDownList();

protected override void OnInit(EventArgs e)
{
    base.OnInit(e);
    _source.ID = String.Format("{0}{1}{2}", ID, IdSeparator, "Source");
    Controls.Add(_source);
}

protected override void Render(HtmlTextWriter writer)
{
    RenderContents(writer);
}

protected override void RenderContents(HtmlTextWriter writer)
{
    _source.RenderControl(writer);
}

问题在于它使用id="MainContent_ComboBox1$Source"和name="ctl00$MainContent$ComboBox1$Source"生成DropDownList.生成的名称符合预期，但ID错误，此处应为 _ 而不是 $ .

Problem is that it generates DropDownList with id="MainContent_ComboBox1$Source" and name="ctl00$MainContent$ComboBox1$Source". Name generated as expected but Id wrong and here should be _ instead of $.

如何实现id="MainContent_ComboBox1_Source"和name="ctl00$MainContent$ComboBox1$Source".

更新1.

试图按照Knaģis的建议将DropDownList放入面板:

Tried to put DropDownList into Panel as Knaģis suggested:

private readonly DropDownList _source = new DropDownList();
private readonly Panel _panel = new Panel();

protected override void OnInit(EventArgs e)
{
    base.OnInit(e);
    _panel.ID = ID;
    _panel.Controls.Add(_source);
    Controls.Add(_panel);
}

protected override void Render(HtmlTextWriter writer)
{
    RenderContents(writer);
}

protected override void RenderContents(HtmlTextWriter writer)
{
    _panel.RenderControl(writer);
}

没有成功.生成的HTML(ID和名称中缺少ComboBox1):

No success. Generated HTML(ComboBox1 in id and name missing):

<div id="MainContent_ComboBox1">
    <select name="ctl00$MainContent$Source" onchange="javascript:setTimeout('__doPostBack(\'ctl00$MainContent$Source\',\'\')', 0)" id="MainContent_Source"></select>    
</div>

答案

如Knaģis所述，我在服务器控件类声明中错过了INamingContainer

As Knaģis suggested I missed INamingContainer in my server control class declaration

public class ComboBox: WebControl, INamingContainer

推荐答案

您应该添加ID为ComboBox1的子面板(或另一个容器控件)，然后在其中添加ID为Source的DropDownList .让ASP.NET生成层次结构标识符.

You should add a child panel (or another container control) with ID of ComboBox1 and then within that add your DropDownList with ID of Source. Let the ASP.NET generate the hierarchical identifiers.

简而言之-如果要为重新设计的控件保留ClientID和Name的值，则应使用与.ascx标记完全相同的控件树.

In short - if you want to preserve the values of ClientID and Name for your reworked control, you should use the exact same control tree as your .ascx markup.

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