如何从页面加载后的代码中获取控件ID [英] How to get Controls ID from code behind on page load

问题描述

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
      Dim lbl_Date As New Label
      Dim i as int16
      i = 20
      While (i < i + 1)
         lbl_Date = TryCast(Page.FindControl("lbl_Date" + i.ToString), Label)
         lbl_Date = "Value"
     i = i + 1
     End While
  End Sub

这在lbl_Date变量中什么也没有返回.如果我在`Page_Load`中不使用它，它就可以正常工作.仅在"Page_Load"中无效.

说明 ::::我想在这里做的是.我有100个标签名称是lable1到lable100.我可以像label1 = Value和label2 = Value之类的来做，但是我正试图放入循环中，所以我的代码更少.仅用于信息... 此代码有效，但不能在Page_Load中使用，我认为这与页面生命周期有关

This is returning Nothing in `lbl_Date` variable. If i don''t use this in `Page_Load`, it works just fine. Only in `Page_Load` it doesn''t work.

Explanation :::: Well what i am trying to do here is . i have 100 label name are lable1 to lable100. I can do like label1 =Value and label2 =Value and so on but i am trying to put in loop so i have less code. just for the Info... This code work but not in Page_Load , I am thinking this has to do with page life cycle

推荐答案

感谢您的回复.我找到了解决方案.

Thanks For the response . I found the Solution .

<asp:content runat="server" id="leftcontent" contentplaceholderid="LeftSidePanel" xmlns:asp="#unknown"> 
    <div id="mydiv"  runat="server"> 
    <asp:linkbutton id="Lnk_Heading1" runat="server"> </asp:linkbutton>
    <asp:label id="lbl_Date1" runat="server"> </asp:label>
    <asp:label id="lbl_Detail1" runat="server"> </asp:label>
    <asp:button id="Button1" runat="server" text="Button" /> 
    </div> 
    </asp:content>

Vb.net *******

Vb.net *******

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load 
   Dim lbl_Date As New Label 
   Dim i as int16 i = 20 
   While (i < i + 1) lbl_Date = TryCast(Mydiv.FindControl("lbl_Date" + i.ToString), Label) 
   lbl_Date = "Value" 
   i = i + 1 
   End While 
   End Sub 

问题是，我没有在aspx页面中使用DIV.当我将代码放在div中并在代码后面使用div的引用时，它就起作用了.

Problem was , I didn''t Used DIV in my aspx page . When i put my code in div and use the reference of the div in codebehind then it work.

当控件呈现为html时，它可能具有不同的ID，该属性被命名为ClientID，但是如果您只想更改所有控件，只需将它们放在容器中并检查它们即可.

在asp.net上将如下所示:

When the control is rendered to html, it might have a diferent ID, the property is named ClientID, but if you want just to change all controls, just place them inside a container and check for them.

on the asp.net would be like this:

<div id="mycontainer" runat="server">
        <asp:Label runat="server" ID="label1" Text="label 1"></asp:Label>
        <asp:Label runat="server" ID="label2" Text="label 2"></asp:Label>
        <asp:Label runat="server" ID="label3" Text="label 3"></asp:Label>
        <asp:Label runat="server" ID="label4" Text="label 4"></asp:Label>
        <asp:Label runat="server" ID="label5" Text="label 5"></asp:Label>
        <asp:Label runat="server" ID="label6" Text="label 6"></asp:Label>
        <asp:Label runat="server" ID="label7" Text="label 7"></asp:Label>
        <asp:Label runat="server" ID="label8" Text="label 8"></asp:Label>
    </div>

而后面的代码(在这种情况下为C#)是这样的:

and the code behind (c# in this case) is like this:

protected void Page_Load(object sender, EventArgs e)
    {
        foreach (var control in mycontainer.Controls)
        {
            Label label = control as Label;
            if (label != null) label.Text = "Found it!";
        }
    }

那应该起作用.
请注意，如果您在页面上附加了任何其他逻辑，则可能需要在PreRender 事件而不是Page_Load事件中执行此操作.
希望对您有所帮助.

That should work.
Please notice that if you attach any other logic to your page, you might want to do that in the PreRender event, instead of the Page_Load.

Hope it helps.

<asp:content runat="server" id="leftcontent" contentplaceholderid="LeftSidePanel" xmlns:asp="#unknown">
    <div id="mydiv"  runat="server">
    <asp:linkbutton id="Lnk_Heading1" runat="server"> </asp:linkbutton>
    <asp:label id="lbl_Date1" runat="server"> </asp:label>
    <asp:label id="lbl_Detail1" runat="server"> </asp:label>
    <asp:button id="Button1" runat="server" text="Button" />
    </div>
    </asp:content>

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
   Dim lbl_Date As New Label
   Dim i as int16 i = 20
   While (i < i + 1) lbl_Date = TryCast(Mydiv.FindControl("lbl_Date" + i.ToString), Label)
   lbl_Date = "Value"
   i = i + 1
   End While
   End Sub

问题是，我没有在aspx页面中使用DIV.当我将代码放在div中并在代码后面使用div的引用时，它就起作用了.

Problem was , I didn''t Used DIV in my aspx page . When i put my code in div and use the reference of the div in codebehind then it work.

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