How to create a query for matching keys? - google-app-engine

Question

I use the key of another User, the sponsor, to indicate who is the sponsor of a User and it creates a link in the datastore for those Users that have a sponsor and it can be at most one but a sponsor can sponsor many users like in this case ID 2002 who sponsored three other users:
In this case this query does what I want: SELECT * FROM User where sponsor =KEY('agtzfmJuYW5vLXd3d3ILCxIEVXNlchjSDww') but I don't know how to program that with python, I can only use it to the datastore. How can I query by key when I want to match the set of users who has the same user as key in the same field? A user in my model can have at most one sponsor and I just want to know who a particular person sponsored which could be a list of users and then they sponsored users in their turn which I also want to query on.
The field sponsor is a key and it has a link to the sponsor in the datastore. I set the key just like user2.sponsor = user1.key and now I want to find all that user1 sponsored with a query that should be just like
User.All().filter('sponsor = ', user1.key)
but sponsor is a field of type key so I don't know how to match it to see for example a list a people the active user is a sponsor for and how it becomes a tree when the second generation also have links. How to select the list of users this user is a sponsor for and then the second generation? When i modelled the relation simply like u1=u2.key ie user2.sponsor=user1.key. Thanks for any hint
The following workaround is bad practice but is my last and only resort:
def get(self):
auser = self.auth.get_user_by_session()
realuser = auth_models.User.get_by_id(long( auser['user_id'] ))
q = auth_models.User.query()
people = []
for p in q:
try:
if p.sponsor == realuser.key:
people.append(p)
except Exception, e:
pass
if auser:
self.render_jinja('my_organization.html', people=people, user=realuser,)
Update
The issues are that the keyproperty is not required and that Guido Van Rossum has reported this as a bug in the ndb when I think it's a bug in my code. Here's what I'm using now, which is a very acceptable solution since every real user in the organization except possibly programmers, testers and admins are going the be required to have a sponsor ID which is a user ID.
from ndb import query
class Myorg(NewBaseHandler):
#user_required
def get(self):
user = auth_models.User.get_by_id(long(self.auth.get_user_by_session()['user_id']))
people = auth_models.User.query(auth_models.User.sponsor == user.key).fetch()
self.render_jinja('my_organization.html', people=people,
user=user)
class User(model.Expando):
"""Stores user authentication credentials or authorization ids."""
#: The model used to ensure uniqueness.
unique_model = Unique
#: The model used to store tokens.
token_model = UserToken
sponsor = KeyProperty()
created = model.DateTimeProperty(auto_now_add=True)
updated = model.DateTimeProperty(auto_now=True)
# ID for third party authentication, e.g. 'google:username'. UNIQUE.
auth_ids = model.StringProperty(repeated=True)
# Hashed password. Not required because third party authentication
# doesn't use password.
password = model.StringProperty()
...

Answer 1

The User model is an NDB Expando which is a little bit tricky to query.
From the docs
Another useful trick is querying an Expando kind for a dynamic
property. You won't be able to use class.query(class.propname ==
value) as the class doesn't have a property object. Instead, you can
use the ndb.query.FilterNode class to construct a filter expression,
as follows:
from ndb import model, query
class X(model.Expando):
#classmethod
def query_for(cls, name, value):
return cls.query(query.FilterNode(name, '=', value))
print X.query_for('blah', 42).fetch()
So try:
form ndb import query
def get(self):
auser = self.auth.get_user_by_session()
realuser = auth_models.User.get_by_id(long( auser['user_id'] ))
people = auth_models.User.query(query.FilterNode('sponsor', '=', realuser.key)).fetch()
if auser:
self.render_jinja('my_organization.html', people=people, user=realuser,)

Answer 2

Option #2
This option is a little bit cleaner. You subclass the model and pass it's location to webapp2. This will allow you to add custom attributes and custom queries to the class.
# custom_models.py
from webapp2_extras.appengine.auth.models import User
from google.appengine.ext.ndb import model
class CustomUser(User):
sponsor = model.KeyProperty()
#classmethod
def get_by_sponsor_key(cls, sponsor):
# How you handle this is up to you. You can return a query
# object as shown, or you could return the results.
return cls.query(cls.sponsor == sponsor)
# handlers.py
def get(self):
auser = self.auth.get_user_by_session()
realuser = custom_models.CustomUser.get_by_id(long( auser['user_id'] ))
people = custom_models.CustomUser.get_by_sponsor_key(realuser.key).fetch()
if auser:
self.render_jinja('my_organization.html', people=people, user=realuser,)
# main.py
config = {
# ...
'webapp2_extras.auth': {
# Tell webapp2 where it can find your CustomUser
'user_model': 'custom_models.CustomUser',
},
}
application = webapp2.WSGIApplication(routes, config=config)