How to run Flask-Login, Flask-BrowserID and Flask-SQLAlchemy in harmony?

Question

The Whole Point

I am attempting to make a fairly basic website with Flask (noob!) and am running into trouble with the user login system. I've decided that I want to use Flask-Login, Flask-BrowserID (Mozilla Persona) and SQLAlchemy. I am going to have Persona be the part that takes care of storing user passwords and such, I am going to use Flask-Login once the user has been authenticated to keep track of their sessions and I am going to use SQLAlchemy to store everything in an sqlite3 db. I've done a lot of bouncing around and I think I have almost finished these features, but I cannot seem to get back a specific error.

Update 1

Based on the comment by davidism, I had to add db.Model to the User class. Unfortunately, that solved the first error, but now there is a new one to deal with. Traceback found below.

The Question

What gives? I am obviously missing something, but I cannot seem to find what that is.

Resources I have been working with

• Flask-BrowserID: https://github.com/garbados/flask-browserid/wiki
• Flask-Login: http://flask-login.readthedocs.org/en/latest/
• Flask-SQLAlchemy: http://pythonhosted.org/Flask-SQLAlchemy/quickstart.html#a-minimal-application
• Is it possible to store Python class objects in SQLite?
• SQLAlchemy Docs: http://docs.sqlalchemy.org/en/rel_0_9/orm/tutorial.html
• WORKING Flask-BrowserID: https://github.com/garbados/flask-browserid/blob/master/tests/init.py

Additional Information

Here is my main.py and index.html I am using with Flask and the Traceback I am getting:

MAIN.py

import sqlite3
from flask import Flask, request, session, g, redirect, url_for, abort, render_template, flash
from contextlib import closing
import time
from flask.ext.login import LoginManager, UserMixin
from flaskext.browserid import BrowserID
from flask.ext.sqlalchemy import SQLAlchemy

## SETUP
DEBUG = True
SECRET_KEY = 'development key'
USERNAME = 'admin'
PASSWORD = 'default'

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/flaskr.db'
db = SQLAlchemy(app)
app.config.from_object(__name__)

app.config['BROWSERID_LOGIN_URL'] = "/login"
app.config['BROWSERID_LOGOUT_URL'] = "/logout"
app.config['SECRET_KEY'] = "deterministic"
app.config['TESTING'] = True

class User(UserMixin, db.Model):
    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.UnicodeText, unique=True)
    firstname = db.Column(db.Unicode(40))
    lastname = db.Column(db.Unicode(40))
    date_register = db.Column(db.Integer)
    bio = db.Column(db.Text)
    facebook = db.Column(db.Unicode(1000))
    twitter = db.Column(db.Unicode(1000))
    website = db.Column(db.Unicode(1000))
    image = db.Column(db.LargeBinary)

    def __init__(self, email, firstname=None, lastname=None, date_register=None, bio=None, facebook=None, twitter=None, 
                    website=None, image=None):
        self.email = email
        self.firstname = firstname
        self.lastname = lastname
        self.date_register = time.time()
        self.bio = bio
        self.facebook = facebook
        self.twitter = twitter
        self.website = website
        self.image = image
        self.email = email

    def __repr__(self):
        return '<User %r>' % self.email

### Login Functions ###
def get_user_by_id(id):
    """
    Given a unicode ID, returns the user that matches it.
    """
    for row in db.session.query(User).filter(User.id == id):
        if row is not None:
            return row.User
    return None

def create_browserid_user(kwargs):
    """
    Takes browserid response and creates a user.
    """
    if kwargs['status'] == 'okay':
        user = User(kwargs['email'])
        db.session.add(user)
        db.session.commit()
        return user
    else:
        return None

def get_user(kwargs):
    """
    Given the response from BrowserID, finds or creates a user.
    If a user can neither be found nor created, returns None.
    """
    import pdb; pdb.set_trace()
    # try to find the user
    for row in db.session.query(User).filter(User.email == kwargs.get('email')):
        if row is not None:
            return row.User
    for row in db.session.query(User).filter(User.id == kwargs.get('id')):
        if row is not None:
            return row.User
    # try to create the user
    return create_browserid_user(kwargs)

login_manager = LoginManager()
login_manager.user_loader(get_user_by_id)
login_manager.init_app(app)

browserid = BrowserID()
browserid.user_loader(get_user)
browserid.init_app(app)

### Routing ###
@app.route('/')
def home():
    return render_template('index.html')

if __name__ == '__main__':
    app.run()

INDEX.html

<html>
    <head>
        <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
        <script src="https://login.persona.org/include.js" type="text/javascript"></script>
        <script type="text/javascript">{{ auth_script|safe }}</script>
    </head>
    <body>
        {% if current_user.is_authenticated() %}
            <button id="browserid-logout">Logout</button>
        {% else %}        
            <button id="browserid-login">Login</button>
        {% endif %}
    </body>
</html>

Traceback

Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1701, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1689, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1687, in wsgi_app
    response = self.full_dispatch_request()
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1360, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1358, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1344, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/jzeller/Classes/CS494/main.py", line 106, in home
    return render_template('test.html')
  File "/Library/Python/2.7/site-packages/flask/templating.py", line 123, in render_template
    ctx.app.update_template_context(context)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 692, in update_template_context
    context.update(func())
  File "/Library/Python/2.7/site-packages/flask_login.py", line 799, in _user_context_processor
    return dict(current_user=_get_user())
  File "/Library/Python/2.7/site-packages/flask_login.py", line 768, in _get_user
    current_app.login_manager._load_user()
  File "/Library/Python/2.7/site-packages/flask_login.py", line 348, in _load_user
    return self.reload_user()
  File "/Library/Python/2.7/site-packages/flask_login.py", line 312, in reload_user
    user = self.user_callback(user_id)
  File "/Users/jzeller/Classes/CS494/main.py", line 60, in get_user_by_id
    print "get_user_by_id - " + str(type(row.User)) + " - " + str(row.User)
AttributeError: 'User' object has no attribute 'User'

Answer 1

Answer to original question

The User model needs to be a subclass of db.Model (or a mapped class) to work with SQLAlchemy.

class User(UserMixin, db.Model):
    ...

Answer to first update

You don't seem to understand what is getting returned by session.query. If you query a single model, the "rows" that are returned are instances of the model. The rows will never be None. When you're checking for existence, you should just use .first() if you are applying filters, or .get(primary_key) if you are filtering by primary key. This gets the first result only since the users are unique anyway

This is what your get_user_by_id should look like:

def get_user_by_id(id):
    return User.query.get(id)

This is what your get_user should look like:

def get_user(kwargs):
    u = User.query.filter(db.or_(
        User.id == kwargs.get('id'),
        User.email == kwargs.get('email')
    )).first()
    if u is None: # user didn't exist in db
        return create_browserid_user(kwargs)
    return u