Get and cast Masterpage UserControl from Content Page to access specific UC Property

Question

I have a MasterPage (MyBoxx.Master) referencing 2 usercontrols :

<%@ Master Language="C#" AutoEventWireup="true" CodeFile="MyBoxx.master.cs" Inherits="MyBoxxMaster" %>
<%@ Register TagPrefix="uc1" TagName="Header" Src="Header.ascx" %>
<%@ Register TagPrefix="uc1" TagName="Footer" Src="Footer.ascx" %>

My user control "Header" contains among other things a searchbox. I want to hide this searchbox when visiting some pages. Therefore I added a boolean property to my user control and use this property when rendering the usercontrol to determinate whether to display the search box or not :

public partial class uxHeader : System.Web.UI.UserControl
{

    bool _showSearch = true;
    public bool ShowSearch
    {
        get { return _showSearch; }
        set { _showSearch = value; }
    }
    [...]
    protected void Page_Load(object sender, EventArgs e)
    {
        [...]
        searchBox.Visible = _showSearch;

    }
}

I then try to access this "ShowSearch" Property from the content page :

((uxHeader)Page.Master.FindControl("Header1")).ShowSearch = false;

Problem is I get the following error when trying to compile :

Error   15  The type or namespace name 'uxHeader' could not be found (are you missing a using directive or an assembly reference?)

The thing is I'm sure I got it to work and compile at some point as it works on the previously released production version. But now I'm doing a change to something else in the same site, and can't compile anymore.

From various post on SO, I tried adding the following lines to my content page aspx :

<%@ MasterType VirtualPath="~/MyBoxx.master"%>
<%@ Reference VirtualPath="~/MyBoxx.master" %>

Without any success ! I saw also some answers about the page Lifecycle, but this can't be the problem here as I'm getting an error on compilation, not a bug upon execution.

If anyone has any advice on how I can fix this for good, I would grandly appreciate.

Thanks !

Answer 1

Well, I found several working solutions... and I think I understood how/why it worked earlier

1) it seems that compilation has a role to play in this. If I comment the line, compile the site, and then try to add the line again, the type uxHeader is "available" in VS and I can compile the site back again with the line uncommented...

2) As first solution is obviously not a long-term solution, I found that referencing the user-control (without actually using it of course) in the content page aspx would do the trick :

<%@ Register TagPrefix="uc1" TagName="Header" Src="Header.ascx" %>

3) I also tried this one, which I find the cleanest... In the master page, expose a public property :

public uxHeader PageHeader
{
    get
    {
        return Header1;//Header1 is the id of the userControl dropped in masterpage
    }
}

In the content page aspx, I then put :

<%@ MasterType VirtualPath="~/DBoxx.master"%>

then, still in the content page, but in the codebehind, and after a compilation of the site, I can use :

this.Master.PageHeader.ShowSearch = false;

Hope this will help the ones searching for help on the subject in the future. I see this is a recurent question

Answer 2

Depending on how you have your User Control coded you may or may not be able to access all it's properties/methods when exposing it to the master page as a master page property..

Here is a solution that works:

In your master page you need to register your user control (.ascx) and place it on the master within the form tag.

Register the User Control

<%@ Register Src="~/Controls/MyUserControl.ascx" TagPrefix="uc" TagName="MyUserControl" %>

Add the User Control to the Master Page

<form id="frmMain" runat="server">
        <uc:MyUserControl runat="server" ID="ucMyUserControl" />
        <div id="main-wrapper">
            <div id="main">...

Now for the content page, you must create a reference in each of the content pages that use the master page for which you want to use the control.

Add the Reference in the content Page

<%@ Reference Control="~/Controls/MyUserControl.ascx" %>

Now you can setup a public variable at the page level and access it's properties/methods

Partial Class MyPage

  Inherits System.Web.UI.Page

  Public usrCtrl As MyUserControl


Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load

    If Master.FindControl("ucMyUserControl") IsNot Nothing Then
        usrCtrl = CType(Master.FindControl("ucMyUserControl"), MyUserControl)
        usrCtrl.ExecMyMethod()
    End If
    ...