CODEWITHSUNDEEP
pythongoogle-app-enginegoogle-cloud-datastoreapp-engine-ndb
sathya Narrayanan
sathya Narrayanan

Reputation: 499

How to query entities without no ancestors in appengine python

Consider the following code snippet:

from google.appengine.ext import ndb
import pprint

class Entity(ndb.Model):
     name = ndb.StringProperty()
     age = ndb.IntegerProperty()

entity = Entity()
entity.name = "hello"
entity.age = 23
entity.key = ndb.Key(Entity, "p1")
entity.put()

e2 = Entity()
e2.key = ndb.Key(Entity, "p2", parent=ndb.Key(Entity, "p1"))
e2.name = "he11o2"
e2.age = 34
e2.put()

I want to query the Entity table records that doesn't have any parent associated with it. For the above example it should yield me only p1 entity.

How can I achieve this ?

Upvotes: 2

Views: 366

Answers (1)

Tim Hoffman
Tim Hoffman

Reputation: 12986

You can't. You can only query for things that exist in an index. Things with no value unless explicity set to None (and you can't do that for parents) can't be queried.

The only way I can suggest is have a computed property or some other property that you set to None if no parent or the parent key or a flag. Then you can query for all entities with parent=None. parent being a property of the entity.

Upvotes: 2

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