Question

I’m trying to create an ascx control that can wrap content like a panel. I’m looking to do something like –

<%@ Register TagPrefix="FOO" TagName="Section" Src="CollapsibleSection.ascx" %>
    <Foo:Section runat="server">
        [ Section of asp.net webforms page ]
    </Foo:Section>

It has been a while since I’ve done web forms and cannot remember if this is possible to do? While I could write a fully custom control, there are many advantages in my app if this is possible.

Answer 1

This is referred to as a templated control.

Here’s a simple tutorial explaining how this is done in both C# and VB.Net: How to: Create Templated ASP.NET User Controls

Quoted from MSDN (link above):

1. In the .ascx file, add an ASP.NET PlaceHolder control where you want the template to appear.
2. In the user control’s code, implement a property of type ITemplate.
3. Define a server control class that implements the INamingContainer interface as a container in which to create an instance of the
   template. This is called the template’s naming container.
4. Apply the TemplateContainerAttribute to the property that implements ITemplate and pass the type of the template’s naming
   container as the argument to the attribute’s constructor.
5. In the control’s Init method, repeat the following steps one or more times:
   • Create an instance of the naming container class.
   • Create an instance of the template in the naming container.
   • Add the naming container instance to the Controls property of the PlaceHolder server control.