how to access master page control from content page

Question

I have a master page which contains a label for status messages. I need to set the status text from different .aspx pages. How can this be done from the content page?

public partial class Site : System.Web.UI.MasterPage
{
    public string StatusNachricht
    {
        get
        {
            return lblStatus.Text;
        }
        set
        {
            lblStatus.Text = value;
        }
    }

    protected void Page_Load(object sender, EventArgs e)
    {            

    }
}

I have tried this, but was unsuccessful in making it work:

public partial class DatenAendern : System.Web.UI.Page
{
    var master = Master as Site;

    protected void Page_Load(object sender, EventArgs e)
    {               
        if (master != null)
        {
            master.setStatusLabel("");
        }
    }        

    protected void grdBenutzer_RowCommand(object sender, GridViewCommandEventArgs e)
    {           
            try
            {
                //some code

                if (master != null)
                {
                    master.setStatusLabel("Passwort erfolgreich geändert.");
                }
            }
            catch (Exception ex)
            {
                if (master != null)
                {
                    master.setStatusLabel("Passwort konnte nicht geändert werden!");
                }                                       
            }
        }
    }                   
}

so u want to access the `label's text property` in all your `aspx` pages....right? — Praveen Nambiar, Mar 22 '13 at 15:02
@LeonidasFett: Should work, so what problem do you have? Have you used the debugger? — Tim Schmelter, Mar 22 '13 at 15:07
i get an error that for var the namespace is not available even though it works when i use it inside a method. and it tells me that Master does not have an object reference... — LeonidasFett, Mar 22 '13 at 15:10
Ah, you cannot initialize the field in this way. Use `Page_Init` to intialize it. — Tim Schmelter, Mar 22 '13 at 15:16

score 93 · Accepted Answer · edited Mar 25 '15 at 17:41

93

In the MasterPage.cs file add the property of Label like this:

public string ErrorMessage
{
    get
    {
        return lblMessage.Text;
    }
    set
    {
        lblMessage.Text = value;
    }
}

On your aspx page, just below the Page Directive add this:

<%@ Page Title="" Language="C#" MasterPageFile="Master Path Name"..... %>
<%@ MasterType VirtualPath="Master Path Name" %>   // Add this

And in your codebehind(aspx.cs) page you can then easily access the Label Property and set its text as required. Like this:

this.Master.ErrorMessage = "Your Error Message here";

edited Mar 25 '15 at 17:41

JonH

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answered Mar 22 '13 at 15:08

Praveen Nambiar

4,852
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1

change the title of this question to more relevant one. 'how to access master page control from content page' – Praveen Nambiar Mar 22 '13 at 15:16
1

ok now i get a NullReferenceException for the label in the property field...i uploaded my new code above. did i miss something here? – LeonidasFett Mar 22 '13 at 15:38
seems like u missed the initialization part that Tim has mentioned below. – Praveen Nambiar Mar 22 '13 at 15:48
hi dear friend this not work on update panel , how can i run this by update panel – R.Akhlaghi Jul 15 '17 at 05:15
you need to call Update method on your updatePanel. If you want to push your changes from the code behind to updatepanel directly. Did work for me. – afr0 Dec 10 '17 at 22:38
If you don't want to add the <%@ MasterType %> line to your aspx, it will also work if you cast the master page to its type in codebehind like so: `((YourMasterPageType)Master).ErrorMessage = "Message";` – AbeyMarquez Mar 23 '18 at 22:01

score 35 · Answer 2 · 2014-04-05T06:50:56.860

35

In Content page you can access the label and set the text such as

Here 'lblStatus' is the your master page label ID

Label lblMasterStatus = (Label)Master.FindControl("lblStatus");

lblMasterStatus.Text  = "Meaasage from content page";

edited Apr 05 '14 at 06:50

answered Apr 05 '14 at 06:37

And if the master has a master, you have to to `Master.Master`. – toddmo Apr 12 '16 at 22:02

score 11 · Answer 3 · edited Oct 31 '14 at 10:28

11

It Works

To find master page controls on Child page

Label lbl_UserName = this.Master.FindControl("lbl_UserName") as Label;                    
lbl_UserName.Text = txtUsr.Text;

edited Oct 31 '14 at 10:28

Diligent Key Presser

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answered Oct 31 '14 at 09:53

shweta

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surya · Answer 4 · 2014-05-20T18:22:31.233

I have a helper method for this in my System.Web.UI.Page class

protected T FindControlFromMaster<T>(string name) where T : Control
{
     MasterPage master = this.Master;
     while (master != null)
     {
         T control = master.FindControl(name) as T;
         if (control != null)
             return control;

         master = master.Master;
     }
     return null;
}

then you can access using below code.

Label lblStatus = FindControlFromMaster<Label>("lblStatus");
if(lblStatus!=null) 
    lblStatus.Text = "something";

Tim Schmelter · Answer 5 · 2013-03-22T15:24:07.567

You cannot use var in a field, only on local variables.

But even this won't work:

Site master = Master as Site;

Because you cannot use this in a field and Master as Site is the same as this.Master as Site. So just initialize the field from Page_Init when the page is fully initialized and you can use this:

Site master = null;

protected void Page_Init(object sender, EventArgs e)
{            
    master = this.Master as Site;
}

Resource · Answer 6 · 2016-03-08T18:01:27.087

This is more complicated if you have a nested MasterPage. You need to first find the content control that contains the nested MasterPage, and then find the control on your nested MasterPage from that.

Crucial bit: Master.Master.

See here: http://forums.asp.net/t/1059255.aspx?Nested+master+pages+and+Master+FindControl

Example:

'Find the content control

Dim ct As ContentPlaceHolder = Me.Master.Master.FindControl("cphMain")

'now find controls inside that content

Dim lbtnSave As LinkButton = ct.FindControl("lbtnSave")

score 1 · Answer 7 · edited Feb 15 '19 at 13:31

If you are trying to access an html element: this is an HTML Anchor...

My nav bar has items that are not list items (<li>) but rather html anchors (<a>)

See below: (This is the site master)

<nav class="mdl-navigation">
    <a class="mdl-navigation__link" href="" runat="server" id="liHome">Home</a>
    <a class="mdl-navigation__link" href="" runat="server" id="liDashboard">Dashboard</a>
</nav>

Now in your code behind for another page, for mine, it's the login page...

On PageLoad() define this:

HtmlAnchor lblMasterStatus = (HtmlAnchor)Master.FindControl("liHome");
lblMasterStatus.Visible =false;

HtmlAnchor lblMasterStatus1 = (HtmlAnchor)Master.FindControl("liDashboard");
lblMasterStatus1.Visible = false;

Now we have accessed the site masters controls, and have made them invisible on the login page.

how to access master page control from content page

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