How do I get a list of namespaces on google app engine?

Question

I would like to make a backup of all user data in the datastore. My application is using the new namespace feature to provide multi tenanting on a per user basis (as per the ex

Answer 1

Using ndb

from google.appengine.ext.ndb import metadata
all_namespaces = [ns for ns in metadata.get_namespaces()]

Using datastore

Per Datastore Metadata:

query = client.query(kind='__namespace__')
query.keys_only()   
all_namespaces = [entity.key.id_or_name for entity in query.fetch()]