NDB query by ancestor returns not entities

Question

I have the following models and respective methods on my project:

class Users(ndb.Expando):
    """
        flefu users, identified by email.
        user_gender --> 0 = male; 1 = female; 2 = other; 3 = unknown
    """
    join_date = ndb.DateTimeProperty(auto_now_add=True)
    user_name = ndb.StringProperty(required=True)
    user_email = ndb.StringProperty(required=True)


class UsersPhotos(ndb.Model):
    """
        property to processes a blob upload steps
        Users child.
    """

    upload_date = ndb.DateTimeProperty(auto_now_add=True)
    photo_key = ndb.BlobKeyProperty(required=True)
    photo_serving_url = ndb.StringProperty(required=True)

    @classmethod
    def insert_from_form(cls, data):
        user_key = ndb.Key(Users, data.userId)

        photo_details = cls(
            parent=user_key,
            user=user_key,
            photo_key=data.photoKey,
            photo_serving_url=data.photoServingUrl
        )

        photo_details.put()
        photo_details.status = "200"
        photo_details.parent = user_key.id()

        return photo_details

   @classmethod
   def get_photos_by_users(cls, data):
       users = Users.query().fetch(20)

       for user in users:

           logging.info(str(user.key))
           photo_data = cls.query(ancestor=user.key).fetch()
           logging.info(str(photo_data))

       photos = cls.query().fetch(10)
       logging.info(str(photos))

I'm not sure why the photo_data query always return an empty list. The empty list is returned on both the Dev app engine service(local) and the hosted app engine service (remote).

The Users and UsersPhotos kinds have the following entities:

Users:

Users(key=Key('Users', 5629499534213120), join_date=datetime.datetime(2014, 7, 26, 4, 40, 11, 840853), user_email=u'[email protected]', user_name=u'hidden')

UsersPhotos:

[
    UsersPhotos(key=Key('Users', '5629499534213120', 'UsersPhotos', 6192449487634432), photo_key=datastore_types.BlobKey('encoded_gs_file:YXBwX2RlZmF1bHRfYnVja2V0L2Zha2UtdzZSYkpZS1RnTlpkY3JKRVI3dUU2UT09'), photo_serving_url=u'http://127.0.0.1:8080/_ah/img/encoded_gs_file:YXBwX2RlZmF1bHRfYnVja2V0L2Zha2UtdzZSYkpZS1RnTlpkY3JKRVI3dUU2UT09=s300', upload_date=datetime.datetime(2014, 7, 26, 4, 40, 35, 455648)), 
    UsersPhotos(key=Key('Users', '5629499534213120', 'UsersPhotos', 6473924464345088), photo_key=datastore_types.BlobKey('encoded_gs_file:YXBwX2RlZmF1bHRfYnVja2V0L2Zha2UtcmZiYU5WNEFSVnZheG81aGQ5dXpNdz09'), photo_serving_url=u'http://127.0.0.1:8080/_ah/img/encoded_gs_file:YXBwX2RlZmF1bHRfYnVja2V0L2Zha2UtcmZiYU5WNEFSVnZheG81aGQ5dXpNdz09=s300', upload_date=datetime.datetime(2014, 7, 26, 4, 41, 12, 322560))
]

Can someone point me on the right direction?

Greg Greg · Accepted Answer · 2014-07-26T14:37:40

You're mixing string and int ids: your Users entities have an int id, but the ID part of the UsersPhotos parent is a string.

When you create the user_key in your insert_from_form method you should cast the value:

user_key = ndb.Key(Users, int(data.userId))

NDB query by ancestor returns not entities

1 Answers