pdf_bypass.rb

  RequestController.class_eval do
    alias_method :orig_get_attachment, :get_attachment

    def skip_attachment_cache
      incoming_message = IncomingMessage.find(params[:incoming_message_id])
      raise ActiveRecord::RecordNotFound.new("Message not found") if incoming_message.nil?
      ir = incoming_message.info_request
      (!authenticated_user.nil?) && (@user == ir.user || @user.is_admin?)
    end

    skip_around_action :cache_attachments, :if => :skip_attachment_cache

    # Special version of get_attachment()
    def get_attachment
      if !skip_attachment_cache
        orig_get_attachment()
        logger.info "using regular get_attachment"
      else
        logger.info "using new get_attachment"
        get_attachment_internal(false)
        return unless @attachment

        # we don't use @attachment.content_type here, as we want same mime type when cached in cache_attachments above
        content_type =
          AlaveteliFileTypes.filename_to_mimetype(params[:file_name]) ||
            'application/octet-stream'

        body = @attachment.default_body

        if content_type == 'text/html'
          body =
            Loofah.scrub_document(body, :prune).
            to_html(encoding: 'UTF-8').
            try(:html_safe)
        end

        logger.debug "Skipping cache"
        render :body => body, :content_type => content_type    
      end
    end
  end