S3 Attachments in paperclip to zip file

s3_attachments_to_zip.rb

format.zip {
                     registrations_with_attachments = Registration.find(:all, :conditions => "abstract_file_name IS NOT NULL")
                     
                     if registrations_with_attachments.size > 0
                       
                       headers['Cache-Control'] = 'no-cache'  
                       tmp_filename = "#{Rails.root.to_s}/tmp/tmp_zip_" <<
                                     Time.now.to_f.to_s <<
                                     ".zip"

                       # zipruby gem
                       Zip::Archive.open(tmp_filename, Zip::CREATE) do |zip|
                       #get all of the attachments

                       # attempt to get files stored on S3
                       # apparently works thanks to Vlad Romascanu;       
                       # http://stackoverflow.com/questions/2338758/zip-up-all-paperclip-attachments-stored-on-s3
                          registrations_with_attachments.each { |e| zip.add_file("abstracts/#{e.abstract.original_filename}", e.abstract.to_file.path) }
                       # Should note that these files in S3 bucket are publicly accessible. 

                       send_data(File.open(tmp_filename, "rb+").read, :type => 'application/zip', :disposition => 'attachment', :filename => tmp_filename.to_s)
                       File.delete tmp_filename
                       
                    else
                        redirect_to registrations_path, :notice => "No attachments to zip up"
                    end
               }