old_contents: from tornado.web import authenticated
  
  from os.path import basename
  
  from .base_handlers import BaseHandler
  from qiita_pet.exceptions import QiitaPetAuthorizationError
  from qiita_db.util import filepath_id_to_rel_path
  from qiita_db.meta_util import get_accessible_filepath_ids
  
  
  class DownloadHandler(BaseHandler):
      @authenticated
      def get(self, filepath_id):
          filepath_id = int(filepath_id)
          # Check access to file
          accessible_filepaths = get_accessible_filepath_ids(self.current_user)
  
          if filepath_id not in accessible_filepaths:
              raise QiitaPetAuthorizationError(
                  self.current_user, 'filepath id %d' % filepath_id)
  
          relpath = filepath_id_to_rel_path(filepath_id)
          fname = basename(relpath)
  
          # If we don't have nginx, write a file that indicates this
          self.write("This installation of Qiita was not equipped with nginx, "
                     "so it is incapable of serving files. The file you "
                     "attempted to download is located at %s" % relpath)
  
          self.set_header('Content-Description', 'File Transfer')
          self.set_header('Content-Type', 'application/octet-stream')
          self.set_header('Content-Transfer-Encoding', 'binary')
          self.set_header('Expires',  '0')
          self.set_header('X-Accel-Redirect', '/protected/' + relpath)
          self.set_header('Content-Disposition',
                          'attachment; filename=%s' % fname)
  
          self.finish()
  
new_contents: from tornado.web import authenticated
  
  from os.path import basename
  
  from .base_handlers import BaseHandler
  from qiita_pet.exceptions import QiitaPetAuthorizationError
  from qiita_db.util import filepath_id_to_rel_path
  from qiita_db.meta_util import get_accessible_filepath_ids
  
  
  class DownloadHandler(BaseHandler):
      @authenticated
      def get(self, filepath_id):
          filepath_id = int(filepath_id)
          # Check access to file
          accessible_filepaths = get_accessible_filepath_ids(self.current_user)
  
          if filepath_id not in accessible_filepaths:
              raise QiitaPetAuthorizationError(
                  self.current_user, 'filepath id %d' % filepath_id)
  
          relpath = filepath_id_to_rel_path(filepath_id)
          fname = basename(relpath)
  
          # If we don't have nginx, write a file that indicates this
          self.write("This installation of Qiita was not equipped with nginx, "
                     "so it is incapable of serving files. The file you "
                     "attempted to download is located at %s" % relpath)
  
          self.set_header('Content-Description', 'File Transfer')
          self.set_header('Content-Type', 'application/octet-stream')
          self.set_header('Content-Transfer-Encoding', 'binary')
          self.set_header('Expires',  '0')
          self.set_header('Cache-Control',  'no-cache')
          self.set_header('X-Accel-Redirect', '/protected/' + relpath)
          self.set_header('Content-Disposition',
                          'attachment; filename=%s' % fname)
  
          self.finish()
  
subject: Reduce likelihood of client caching