code: def _process_file(self, obj, fobj, field):
          
          from uliweb import settings
          
          paths = []
          upload_to = self.upload_to or self._get_upload_path(field, 'upload_to', obj)
          if upload_to:
              self.fileserving.to_path = upload_to
          upload_to_sub = self.upload_to_sub or self._get_upload_path(field, 'upload_to_sub', obj)
          if upload_to_sub:
              paths.append(upload_to_sub)
          paths.append(fobj['filename'])
          
          return self.fileserving.save_file(os.path.join(*paths), 
              fobj['file'], replace=self.file_replace, 
              convert=self.file_convert)
docs: obj is record object
          fobj is data
          field is FileField instance