Using OpenID auth, which is the proper User instance method to get a unique identifier useful for creating and identifying a user on Datastore as key_name?
Available methods :
nickname() For OpenID users, the nickname is the OpenID identifier.
federated_identity() Returns the user's OpenID identifier.
federated_provider() Returns the URL of the user's OpenID provider.
On user logins i would like to retrieve it by:
User.get_by_key_name(key_used_to_create_the_user)