You should subclass UserMixin on your model. You should also add a user_loader

from flask.ext.login import UserMixin
from yourapp import login_manager

@login_manager.user_loader
def get_user(ident):
  return User.query.get(int(ident))


class User(db.Model, UserMixin)
  id = db.Column(db.Integer, primary_key=True)
  ### yada yada, you know what goes here