MVC 3 compression filter causing garbled output

Question

So, I have a custom attribute called CompressAttribute which is set up as a global filter in global.asax. It uses reflection to examine the return type of the current action

Answer 1

The accepted answer won't work if anything has been already written to the output.

Instead of disposing the filter you can make sure the headers are being persisted in place:

 protected void Application_PreSendRequestHeaders()
{
    // ensure that if GZip/Deflate Encoding is applied that headers are set
    // also works when error occurs if filters are still active
    HttpResponse response = HttpContext.Current.Response;
    if (response.Filter is GZipStream && response.Headers["Content-encoding"] != "gzip")
        response.AppendHeader("Content-encoding", "gzip");
    else if (response.Filter is DeflateStream && response.Headers["Content-encoding"] != "deflate")
        response.AppendHeader("Content-encoding", "deflate");
}