如何使用ASP.NET C中的子页面访问母版页div [英] How to access master page div using child page in ASP.NET C#

问题描述

从我的项目的第二页移动后，我想在母版页的标签控制中设置值。



请建议我一些想法。



我试过以下代码，但是它会抛出错误



对象引用未设置为对象的实例。



我尝试了什么：



我试过以下代码： -





标签lblSubHd = this.Master.FindControl（lblSubHd）作为标签;

lblSubHd .Visible = true;

解决方案

您好，



您不能直接访问主要组件页。它的分配属于受保护的类型。



为了访问标签组件，我建议您在母版页中使用公共属性。



主页中的HTML代码

 <   div  >  
 < ;   asp：标签    ID   =  lblSubHd    runat   =  server   文本  = 嗯Texto >  < ;   / asp：标签 >  
 <   asp：ContentPlaceHolder     ID   =  ContentPlaceHolder1    runat   =  server >  
 
 <   / asp ：ContentPlaceHolder  >  
 <   / div  >  

访问组件，这里是代码。

母版页的代码隐藏

 公开标签MyLabel 
 {
 获取 
 {
  return   this  .lblSubHd; 
} 
} 

代码隐藏到子页面

标签mylabelchild =  this  .Master.MyLabel; 

访问文本属性标签组件，这里是代码。

母版页的代码隐藏

  public   string  ValueLabel 
 {
  get  
 {
  return   this  .lblMyLabel.Text; 
} 
} 

代码隐藏到子页面

  this  .MylabelChild.Text =  this  .Master.ValueLabel; 

重要！对于您使用上面的解决方案，您的子页面需要在asp标记中包含母版页。

 <％@     Page    语言  =  C＃    AutoEventWireup   =  true     MasterPageFile   = < span class =code-keyword>〜/ Main.Master    CodeBehind   =  child_page.aspx.cs   继承  =  aplicacao.child_page   ％>  
 <％@     MasterType     VirtualPath   = 〜/ Main.Master    ％GT;  

After moving from second page of my project,i want to set value in label control of master page.

please suggest me some idea.

I have tried following code,but it throws an error

Object reference not set to an instance of an object.

What I have tried:

I have tried following code:-


Label lblSubHd = this.Master.FindControl("lblSubHd") as Label;
lblSubHd.Visible = true;

解决方案

Hi,

You do not directly access a component of the main page. Its assignatury is of the protected type.

For you access the label component, I suggest that you use public properties in your master page.

HTML code in your master page

<div>
    <asp:Label ID="lblSubHd" runat="server" Text="Um Texto"></asp:Label>
    <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
   
    </asp:ContentPlaceHolder>
</div>

To access the component, here, the code.
Code-behind to master page

public Label MyLabel
{
   get
   {
      return this.lblSubHd;
   }
}

Code-behind to child page

Label mylabelchild = this.Master.MyLabel;

To access the text property of the label component, here, the code.
Code-behind to master page

public string ValueLabel
{
    get
    {
      return this.lblMyLabel.Text;
    }
}

Code-behind to child page

this.MylabelChild.Text = this.Master.ValueLabel;

IMPORTANT! For you use the solution above your child page need to have the master page in asp tag.

<%@ Page Language="C#" AutoEventWireup="true" MasterPageFile="~/Main.Master" CodeBehind="child_page.aspx.cs" Inherits="aplicacao.child_page" %>
<%@ MasterType VirtualPath="~/Main.Master" %>

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