Hide Panel on Child MasterPage Inside MasterPage ContentPlaceHolder using Child Content Page

Question

I've tried to find this solution everywhere, but am unable to make it work.

I have the following code.

MasterPage.master:

<%@ Master Language="C#" AutoEventWireup="true" CodeFile="MasterPage.master.cs" Inherits="My_MasterPage" %>

<asp:ContentPlaceHolder id="ContentPlaceHolder1" runat="server"></asp:ContentPlaceHolder>

ChildMasterPage.master:

<%@ Master Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="ChildMasterPage.master.cs" Inherits="My_ChildMasterPage" %>
<%@ Register TagPrefix="uc1" TagName="FileDirectoryOrganizer" Src="~/Controls/my.ascx" %>


<asp:Content ID="Content7" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">

<asp:panel id="SideNav" runat="server">

    <aside id="sideBar">

        There are 2 User Controls <asp:uc1> inside of this area

    </aside>

</asp:panel>

<div>
    <asp:ContentPlaceHolder ID="contentBody" runat="server" />
    <hr />
    <h3>Related Topics</h3>
</div>

</asp:Content>

my.aspx:

<%@ Page Title="" Language="C#" MasterPageFile="~/SubDirectory/ChildMasterPage.master" AutoEventWireup="true" CodeFile="my.aspx.cs" Inherits="SubDirectory_my" %>
<%@ MasterType VirtualPath="~/SubDirectory/ChildMasterPage.master" %>
<%@ Reference VirtualPath="~/MasterPage.master" %>

<asp:Content ID="Content1" ContentPlaceHolderID="contentBody" Runat="Server">
</asp:Content>

I've tried the following in the my.aspx code behind to hide the "SideNav" Panel from the ChildMasterPage.master:

1)

protected void Page_Load(object sender, EventArgs e)
{
    ContentPlaceHolder cpHolder = this.Master.FindControl("Content7") as ContentPlaceHolder;
    Panel p = cpHolder.FindControl("SideNav") as Panel;
    p.Visible = false;
}

2)

protected void Page_Load(object sender, EventArgs e)
{
    ContentPlaceHolder cpHolder = this.Master.FindControl("ContentPlaceHolder1") as ContentPlaceHolder;
    Panel p = cpHolder.FindControl("SideNav") as Panel;
    p.Visible = false;
}

3)

protected void Page_Load(object sender, EventArgs e)
{
    Panel p = this.Master.FindControl("SideNav") as Panel;
    p.Visible = false;
}

All of these give me the following error when trying to load the aspx page that uses the ChildMasterPage:

 500 - Internal server error.
 There is a problem with the resource you are looking for, and it cannot be displayed.

Ultimately, I'd like to get it to display none with a style so the space is not used on the aspx page. Something like this, which gives me the same error as above:

protected void Page_Load(object sender, EventArgs e)
{
    ((Panel)this.Page.Master.FindControl("SideNav")).Style.Add("display", "none");
}

Thank you in advance for any assistance you may offer. Also, I apologize in advance if this question has been answered here already, but I was unable to find it. At least nothing that worked. I'm still not very good with C#, but I'm getting there.

Thanks

Mark

Answer 1

I think you have type cast the Content control into ContentPlaceHolder control in your first approach.

I believe the code should be like below:

Content cpHolder = this.Master.FindControl("Content7") as Content;

Hope this will help !!

Answer 2

Instead of trying to force the my.aspx.cs to "see" the Panel on the ChildMasterPage.master, I did the following:

my.aspx.cs

public partial class SubDirectory_my : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        My_ChildMasterPage hideMySideBar = this.Master;
        hideMySideBar.HideSideBar();
    }

ChildMasterPage.master

public void HideSideBar()
{
    SideNav.Visible = false;
}

This casts the class of the Child Master page to a new variable, then the variable can act on, or call the function in the Child Master Page code behind from the my.aspx code behind. Thanks goes to my co-worker for figuring this one out.