Flask-SqlAlchemy, Bcrypt, Postgres issue with encoding

Question

I'm writing my first API from scratch and have a /login endpoint that errors when verifying a users password with bcrypt but only when using Postgres as my DB, works correctly when using SQLite3.

Also, any assistance in better ways to structure anything in my models or route is always welcome, this is my first API in Flask / Python so I'm still learning.

Thanks in advance!

Error:

* Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
[2021-06-22 12:06:14,415] ERROR in app: Exception on /api/v1/login [POST]
Traceback (most recent call last):
  File "C:\Users\x4c8\Projects\money_api\venv\lib\site-packages\flask\app.py", line 2070, in wsgi_app
response = self.full_dispatch_request()
File "C:\Users\x4c8\Projects\money_api\venv\lib\site-packages\flask\app.py", line 1515, in full_dispatch_request
rv = self.handle_user_exception(e)
File "C:\Users\x4c8\Projects\money_api\venv\lib\site-packages\flask\app.py", line 1513, in full_dispatch_request
rv = self.dispatch_request()
File "C:\Users\x4c8\Projects\money_api\venv\lib\site-packages\flask\app.py", line 1499, in dispatch_request
return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)
File "C:\Users\x4c8\Projects\money_api\routes.py", line 47, in token_get
check = user.verify_password(password)
File "C:\Users\x4c8\Projects\money_api\models.py", line 40, in verify_password
return bcrypt.checkpw(enc_pw, self.password_hash)
File "C:\Users\x4c8\Projects\money_api\venv\lib\site-packages\bcrypt\__init__.py", line 120, in checkpw
raise TypeError("Unicode-objects must be encoded before checking")
TypeError: Unicode-objects must be encoded before checking
127.0.0.1 - - [22/Jun/2021 12:06:14] "POST /api/v1/login HTTP/1.1" 500 -

User class in Models.py:

class User(db.Model, Serializer):
__tablename__ = 'user'
id = db.Column(db.Integer, primary_key=True)
first_name = db.Column(db.String(15), unique=False, nullable=True)
last_name = db.Column(db.String(20), unique=False, nullable=True)
email = db.Column(db.String(120), unique=True, nullable=False)
password_hash = db.Column(db.String(255), unique=False, nullable=False)
country = db.Column(db.String(2), unique=False, nullable=True)
subscription_level = db.Column(db.Integer, default=0)
subscription_purchase_date = db.Column(db.DateTime(), unique=False, nullable=True)
last_login = db.Column(db.DateTime(), unique=False, default=datetime.utcnow)
modified_at = db.Column(db.DateTime(), unique=False, default=datetime.utcnow)
created_at = db.Column(db.DateTime(), unique=False, default=datetime.utcnow)

# relationships
portfolios = db.relationship('StockPortfolio', foreign_keys='StockPortfolio.fk_user', backref='user',
                             lazy='dynamic', cascade='all, delete-orphan')

@property
def password(self):
    raise AttributeError('password not readable')

@password.setter
def password(self, password):
    enc_pw = password.encode('utf-8')
    self.password_hash = bcrypt.hashpw(enc_pw, bcrypt.gensalt()).decode('utf-8')

def verify_password(self, password):
    enc_pw = password.encode('utf-8')
    return bcrypt.checkpw(enc_pw, self.password_hash)

def serialize(self):
    d = Serializer.serialize(self)
    del d['password_hash']
    del d['modified_at']
    del d['created_at']
    del d['last_login']
    return d

/login from routes.py

# POST /login
@routes.route(api_v1 + 'login', methods=['POST'])
def token_get():
    if request.method == 'POST':
        body = request.get_json()

        # fail on missing params
        if body.get('email') is None:
            return jsonify(msg='email parameter is missing'), 422
        if body.get('password') is None:
            return jsonify(msg='password parameter is missing'), 422

        # fail on email not in use
        user = User.query.filter_by(email=body.get('email')).first()
        if user is None:
            return jsonify(msg='Email is not in use'), 404
        else:
            password = body.get('password')
            check = user.verify_password(password)

            if check:
                # record last login
                user.last_login = datetime.utcnow()

                # prep and return tokens
                access_token = create_access_token(identity=user.id)
                refresh_token = create_refresh_token(identity=user.id)
                return jsonify(msg='login successful', access_token=access_token, refresh_token=refresh_token), 200
            else:
                return jsonify(msg='incorrect email or password'), 409

Answer 1

You need just change this part of the code to convert password_hash to bytes:

def verify_password(self, password):
    enc_pw = password.encode('utf-8')
    return bcrypt.checkpw(enc_pw, bytes(self.password_hash, 'utf-8'))