登录正常，但current_user未通过身份验证

Question

My login is working but a current user is not being created / is not authenticated.

Login manager:

@login_manager.user_loader
    def load_user(username):
    #users is my mongodb collection
    user = users.find_one({"_id": username})
    if not user:
       return None
    return User(user['_id'])

Login route:

@app.route("/login", methods=['GET', 'POST'])
def login():

  login = LoginForm()

  if current_user.is_authenticated:
    return redirect(url_for('feed'))

  if login.submit.data and login.validate():
      #users is my mongodb collection
      user = users.find_one({"email": login.email.data})
      if user and User.validate_login(user['password'], login.password.data):
        user_obj = User(json_util.dumps(user['_id']))
        login_user(user_obj, remember=login.remember.data)
        flash(f'Login Successful, welcome {user["name"]}.', 'success')
        return redirect(url_for('feed'))
      else:
        flash('Login Unsuccessful. Please check email and password', 'warning')

  return render_template(
    'login.html',
    login=login
  )

User class:

class User():

def __init__(self, username):
    self.username = username

def is_authenticated(self):
    return True

def is_active(self):
    return True

def is_anonymous(self):
    return False

def get_id(self):
    return self.username

@staticmethod
def validate_login(password_hash, password):
    return bcrypt.check_password_hash(password_hash, password)

Feed route:

@app.route("/feed")
def feed():

  if not current_user.is_authenticated:
    #flash(f'{current_user.is_authenticated} {current_user._id}', 'warning')
    return redirect(url_for('welcome'))

#etc etc 

After being logged in the user is meant to be redirect to the feed route, this works however you are redirected back due to not being authenticated.

I've seen session be used to get around this problem however still curious to the solution of this.

Sources I've consulted:

• Why isn't my current_user authenticated in flask-login?
• https://medium.com/@dmitryrastorguev/basic-user-authentication-login-for-flask-using-mongoengine-and-wtforms-922e64ef87fe
• https://boh717.github.io/post/flask-login-and-mongodb/

Answer 1

Solution: I was searching mongoDB using a string instead of an ObjectId in the load_user. I worked this out my switching to searching with the users imputed email, it working and I noticed my problem.

@login_manager.user_loader
def load_user(user_id):
    user = users.find_one({"_id": ObjectId(user_id)})
    if not user:
        return None
    return User(str(user['_id'])

Lesson learnt, strings != ObjectId(s). I hope this helps anyone who is having a similar problem!