Question

I have a non-ndb entity that is created and a webapp2 User who owns this object. Is it possible to keep the key as an instance variable? I get an exception trying to do this:

'Ad' object has no attribute '_values'
Traceback (most recent call last):
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1511, in __call__
    rv = self.handle_exception(request, response, e)
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1505, in __call__
    rv = self.router.dispatch(request, response)
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1253, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 1077, in __call__
    return handler.dispatch()
  File "/base/data/home/apps/s~montaoproject/sessions.358423846858516313/authhandlers.py", line 21, in dispatch
    webapp2.RequestHandler.dispatch(self)
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 547, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/base/python27_runtime/python27_lib/versions/third_party/webapp2-2.3/webapp2.py", line 545, in dispatch
    return method(*args, **kwargs)
  File "/base/data/home/apps/s~montaoproject/sessions.358423846858516313/main.py", line 3004, in post
    ad.usr = self.current_user.key
  File "/base/data/home/apps/s~montaoproject/sessions.358423846858516313/ndb/model.py", line 1039, in __set__
    self._set_value(entity, value)
  File "/base/data/home/apps/s~montaoproject/sessions.358423846858516313/ndb/model.py", line 801, in _set_value
    self._store_value(entity, value)
  File "/base/data/home/apps/s~montaoproject/sessions.358423846858516313/ndb/model.py", line 785, in _store_value
    entity._values[self._name] = value
AttributeError: 'Ad' object has no attribute '_values'

The offending code

if self.current_user:
    logging.info('user:'+str(self.current_user))
    ad.usr = self.current_user.key
    ad.put

Model

class Ad(GeoModel, search.SearchableModel):

    primary_image = blobstore.BlobReferenceProperty()
    usr = ndb_model.KeyProperty()
    ...

Is there a recommended way to do what I’m trying to do?

Thanks

Answer 1

The Key types in NDB and db are different. You must convert the NDB Key (self.current_user.key) to a db.Key instance as follows:

ad.usr = self.current_user.key.to_old_key()

See https://developers.google.com/appengine/docs/python/ndb/keyclass#Key_to_old_key