Subclassing DropDownList in ASP.NET

Question

I want to subclass the built-in DropDownList in ASP.NET so that I can add functionality to it and use it in my pages. I tried doing this with a UserControl but found that it

Answer 1

You want to extend DropDownList in a Custom Control... not in a usercontrol.

Create a new Class Library Project called MyLibrary.

Add a class called MyDropDownList.cs

namespace My.Namespace.Controls
{
[ToolboxData("<{0}:MyDropDownList runat=\"server\">")]
public class MyDropDownList: DropDownList
{
    // your custom code goes here
    // e.g.
    protected override void  RenderContents(HtmlTextWriter writer)
    {
        //Your own render code
    }
}
}

Once you compile your library, you can add a reference to it in your web application.

And a tagprefix in your web.config

That should allow you to add this to your aspx/ascx's

    ...