i am using the `webapp2_extras.appengine.auth.models.User` service which basically extends the `google.appengine.api.users model`. Now , I have custom users registered with my application and they have a lot of custom fields. The problem is i want to filter / (multi filter) all the users using various custom fields. For example: 

the user model has 2 fields `is_active` and `activation_key` now i want to filter them using these fields, example:

```
from google.appengine.api import users

act_key = 'hw-2j38he63u83hd6hak3FshSqj3TGemn9'
user = users.all().filter('is_active =', False).filter('activation_key =', act_key).get()
if user:
  return True
else:
  return False

```

what are the best possible ways to filter on the user model using custom fields?

Edit:

Also tried the following:

```
from webapp2_extras.appengine.auth.models import User

query = User.query().filter('is_active =', False)
print query

```

but this raises an error as follows:

```
Traceback (most recent call last):
File "/opt/google_appengine_1.6.4/google/appengine/ext/admin/__init__.py", line 320, in post
exec(compiled_code, globals())
File "<string>", line 6, in <module>
File "lib/ndb/query.py", line 968, in filter
raise TypeError('Cannot filter a non-Node argument; received %r' % arg)
TypeError: Cannot filter a non-Node argument; received 'is_active ='

```