module ActionDispatch::Http::MimeNegotiation

def accepts
  fetch_header("action_dispatch.request.accepts") do |k|
    header = get_header("HTTP_ACCEPT").to_s.strip
    v = if header.empty?
      [content_mime_type]
    else
      Mime::Type.parse(header)
    end
    set_header k, v
  rescue ::Mime::Type::InvalidMimeType => e
    raise InvalidType, e.message
  end
end