ASP.NET Dynamically Change User Control Source

Question

The Scenario

I have an ASP.Net Web Project that uses a master page. This master page contains a menu in the form of a user control. Sometimes I want to dynamically change this to use a different type of menu user control.

The current code to register the user control

<%@ Register TagPrefix="chase" TagName="topMenu"  Src="~/UserControls/TopMenu.ascx" %>

Inside the body tags

 <div id="menuRow">
     <chase:topMenu runat="server" />
 </div>

The Question

Is there anyway I can change the "SRC" attribute in the register code dynamically to use a different user control?!

Help greatly appreciated

EDIT:

Tried This Code But I Receive An 'Invalid Cast Exception'

TopMenu uh3 = (TopMenu)this.LoadControl("~/UserControls/TopMenu.ascx");
            menuRow.Controls.Add(uh3);

'Unable to cast object of type 'ASP.usercontrols_topmenu_ascx' to type 'SwintonTaxiWeb.UserControls.TopMenu'.'

Answer 1

Would you try having the two user controls registered on page and hide/disable accordingly.

Answer 2

What if you add your user control at runtime whichever you need.

UserControls_header3 uh3 = (UserControls_header3)this.LoadControl(header3);
phHeaderControls.Controls.Add(uh3);

Answer 3

What's causing the dynamic changes?

You could do this in the server side code fairly easily.

In your .aspx page you could have:

<asp:Panel id="menuRow" runat="server">
</asp:Panel>

I'm using a Panel here because it gives us a nice container for controls, and outputs a <div> tag around them.

Then in your code behind, you'd have something like:

// Determine correct user control to load
string pathToUserControl = DetermineTopMenu();

// Load the user control - calling LoadControl forces the correct lifcycle events
// to fire, and ensures the control is created properly.
var topMenu = LoadControl(pathToUserControl);

// Add the control to the menuRow panels control collection.
menuRow.Controls.Add(topMenu);

I've assumed that you have some way to work out which user control you want to display, and that you've named them in such a way that generating the path to the user control is fairly trival. I've hidden that logic in the method call DetermineTopMenu because:

1. I don't know what logic you're using
2. It makes it easier to test, extend, etc.

For more information on LoadControl, check the documentation.

Answer 4

With regards to your problem about the InvalidCastException, maybe this MSDN page will help. You can try setting the class name of your control in the control's <%@ Control %> tag.