'NoneType' object has no attribute 'filter'

[erickrocha]

Flask-MongoAlchemy==0.7.2

from flask_mongoalchemy import Document
my class
class User(Document):
id = db.StringField()
email = db.StringField()
password = db.StringField()
name = db.StringField()

`from flask import request, make_response, jsonify, current_app
from time import time
from app.models import User
from app.security import bp

@bp.route('/freeman/login', methods=['POST'])
def login():
email = request.json['email']
password = request.json['password']
user = User.query.filter(User.email == email)
if user is None or not user.check_password(password):
return make_response(jsonify({'error': 'Unauthorized access'}), 401)
expires_in = time() + current_app['EXPIRATION_TIME']
secret_key = current_app['SECRET_KEY']
token = user.login(secret_key, expires_in)
return make_response(jsonify({'type': 'bearer', 'token': token, 'expireIn': expires_in}), 200)

@bp.route('/freeman/api/users', methods=['GET'])
def get_users():
users = User.query.all()
return make_response(jsonify({'users': users}), 200)`

I debugged and I don know what's happens, but my query object has no instance and looking the documentation it's OK