How to Accessing Master Control(Link Button) from Content pages?

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In my project, I need to set Visible/Invisibel Link Button
I used the Follwoing Code::

C#

LinkButton masterControl = (LinkButton)this.Master.FindControl("lnkbPostDetails");                       
   if ( User == "Honey")
   {
      masterControl.Visible = true;
   }
   else
   {
      masterControl.Visible = false;
   }

When i am execting the above the code i m getting the follwoing error, at the line
LinkButton masterControl = (LinkButton)this.Master.FindControl("lnkbPostDetails");

NullReferenceException was Handled by user code.
Object reference not set to an instance of an object.
Thanks & regards

Honey.

Posted 25-May-12 23:24pm

honey4bee

Updated 26-May-12 0:13am

v3

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Technoses 26-May-12 6:28am

remove
xmlns:asp="#unknown"
from tags

this is a code project problem

3 solutions

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Shahin Khorshidnia · Answer 1 · 2012-05-25T23:43:00

Solution 1

ASP.NET - Accessing Master Page elements form the Content Page

For information?
Working with ASP.NET Master Pages Programmatically

Posted 25-May-12 23:43pm

Shahin Khorshidnia

Updated 25-May-12 23:48pm

v2

Technoses · Answer 2 · 2012-05-26T00:27:00

YOu can dow following process:

For Master Page
aspx page

ASP.NET

<div>
   <asp:label id="lblName" text="BBB" runat="Server" xmlns:asp="#unknown"></asp:label>
   <asp:linkbutton id="lnkbPostDetails" text="AAA" runat="Server" xmlns:asp="#unknown"></asp:linkbutton>
       <asp:contentplaceholder id="ContentPlaceHolder1" runat="server" xmlns:asp="#unknown">
       </asp:contentplaceholder>
   </div>

aspx.cs page

C#

public partial class Master_test3_MasterPage : System.Web.UI.MasterPage
{
    public LinkButton lnkbPostDetailsMS;
    protected void Page_Init(object sender, EventArgs e)
    {
        lnkbPostDetailsMS = lnkbPostDetails;
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        
    }
}

Content Page

Aspx.cs page

C#

protected void Page_Load(object sender, EventArgs e)
{
    Master_test3_MasterPage ms = (Master_test3_MasterPage)this.Master;
    ms.lnkbPostDetailsMS.Visible = false;
}

Sandeep Mewara · Answer 3 · 2012-05-26T07:33:00

Solution 3

Object reference not set to an instance of an object.
This error happens when you try to use a property or call a method of an object that is null. More details: here[^]

Based on what you have shared, it means,
1. Either, there is no Master page for the given page. OR
2. this.Master.FindControl("lnkbPostDetails") returns NULL and when you try to cast it into LinkButton, it throws an error. Check if their is linkbutton on MasterPage as defined.

Posted 26-May-12 7:33am

Sandeep Mewara

Comments

honey4bee 29-May-12 7:08am

Hi Sandeep,
Link Button exists in my master page, I m pasting here Html code of link button exsisting,

<tr>
<td bgcolor="#CC9900" height="300px" valign="top">
<br />
<asp:LinkButton ID="lnkbPostDetails" runat="server" OnClick="lnkbPostDetails_Click">Post Details
</td>
<td bgcolor="#FFFFFF" valign="top" colspan="2" >
<div>
<asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">

</div>
</td>
</tr>

Sandeep Mewara 29-May-12 7:42am

If this is your master page HTML, linkbutton can be directly accessed. Why to use a FindControl?

honey4bee 30-May-12 1:18am

In the Intelligency Master Page not comes, then how I can directly access link button..

Sandeep Mewara 30-May-12 7:27am

In Masterpage.cs file, directly access lnkbPostDetails control object.