code: def set(self, instance, value, **kw):
          
          value = str(value).decode("base64")
  
          # handle the filename
          if "filename" not in kw:
              logger.debug("FielFieldManager::set: No Filename detected "
                           "-> using title or id")
              kw["filename"] = kw.get("id") or kw.get("title")
  
          self._set(instance, value, **kw)
docs: Decodes base64 value and set the file object