Python Flask “Invalid Credentials”

Question

I am new to Flask learning it from a tutorial video. I am trying to authenticate and get a access token. I have created user class which is in user.py :

    class User:
    def __init__(self, _id, username, password):
        self.id = _id,
        self.username = username,
        self.password = password

in my security.py :

from werkzeug.security import safe_str_cmp
from user import User

users = [
    User(1, 'user1', 'abcxyz'),
]

username_table = {u.username: u for u in users}
userid_table = {u.id: u for u in users}

def authenticate(username, password):
    user = username_table.get(username, None)
    print(username) # user1
    print(password) # abcxyz
    print(username_table) #{('user1',): <user.User object at 0x000001AD37543358>}
    print(user) # None
    if user and safe_str_cmp(user.password.encode('utf-8'), password.encode('utf-8')):
        return user

def identity(payload):
    user_id = payload['identity']
    return userid_table.get(user_id, None)

As you can see I was trying to debug with printing out everything. Inside authentication function I got username and password successfully from the request. But In result the user variable is None. Looks like .get method is not working and that is causing the error but I can not figure out why am I getting None there. I have showed the outputs in front of print functions

Answer 1

I think you have a typo in your program. Please remove the , after the username in __init__ of the User class. That is syntactically correct and way of creating a tuple with a single element which is not what you need.

>>> tuple_with_single_element = "python",
>>> tuple_with_single_element
... ('python',)
>>> python_string = "python"
>>> python_string
... 'python'