Matthew Knott

After wasting a morning trying to get this example of how to get a webpart to register a css file dynamically to work, I realised how it's actually done, and it is far, far simpler.

With the above example, I kept receiving the message "The given path's format is not supported", that was after I turned Custom Errors off, as prior to that all I saw was "Unexpected Error".

You actually only need one line of code in your OnInit or OnPreRender methods.

1. CssRegistration.Register("/_layouts/css/mycss.css");

There is built-in validation to ensure the file is not registered twice. Enjoy.

Update

I've been using the code below for a long time now, it's the most reliable solution I've found.

1. try
2. {
3. ContentPlaceHolder header = (ContentPlaceHolder)this.Page.Master.FindControl("PlaceHolderAdditionalPageHead");
4. if (header != null)
5. {
6. string relativePath = this.ClassResourcePath.Remove("://");
7. relativePath = relativePath.Substring(relativePath.IndexOf("/"), (relativePath.Length - relativePath.IndexOf("/")));
8. Literal cssControls = new Literal();
9. cssControls.Text = "";
10. header.Controls.Add(cssControls);
11. }
12. }
13. catch (Exception ex)
14. {
15. string relativePath = this.ClassResourcePath.Remove("://");
16. relativePath = relativePath.Substring(relativePath.IndexOf("/"), (relativePath.Length - relativePath.IndexOf("/")));
17. CssRegistration.Register(relativePath + "/mycss.css");
18. }