AttributeError: 'Flask' object has no attribute 'login_manager' -- Login_Manager

Question

I am having issue with Login_manager in my application . The error is thrown here

def authenticate(form):
    if form.validate_on_submit():
        try:
            user = session.query(User).filter(User.email == form.email.data).first()
        except :# models.DoesNotExist:
            flash("Your email or password does not match !", "error")
        else :
            if check_password_hash(user.password,form.password.data):
                login_user(user)
                flash("You've been logged in", "success")
                return redirect(url_for('index'))
            else :
                flash("Your email or password does not match !", "error")
    return render_template('login.html',form = form)  

The issue is raise at

login_user(user)

my login_manager is configured below the autheticate as follows.

if __name__ == '__main__':

    app.secret_key = 'Innalhamdulillah.nahmaduhu.taalanastainubihi.wanastagfiruh!'
    app.run(debug = DEBUG, host=HOST, port= PORT)

    login_manager = LoginManager()
    login_manager.init_app(app)
    login_manager.login_view = 'login'

    @login_manager.user_loader
    def load_user(userid):
        try:
            return session.query(User).filter(User.id == userid).first()
        except models.DoesNotExist :
            return None

and in my declaration

from flask.ext.login import LoginManager,login_user

Please how do i addressed this issue and what is the cause ? How do i better understand it ? I was suspecting my def load_user(userid): bcos i am not very much clear and this my first. Any help would be appreciated.

Answer 1

You run your app before initializing the LoginManager. So you should have:

app.secret_key = 'xxxxyyyyyzzzzz'

login_manager = LoginManager()
login_manager.init_app(app)
login_manager.login_view = 'login'

app.run(debug = DEBUG, host=HOST, port= PORT)

Answer 2

I'm just learning Flask, and I encountered this problem too. I found that I had not initialized the login_manager to the app.

So I changed:

login_manager = LoginManager()

to

login_manager = LoginManager(app)

and that solved my issue.

Answer 3

All flask extensions need to be initilized. Initialize the login manager for use in the app like this:

login_manager = LoginManager()
login_manager.login_view = 'auth.login'

and don't forget this:

login_manager.init_app(app) 

If it is not initialized it will raise errors that look like this:

Exception: Missing user_loader or request_loader. Refer to http://flask-login.readthedocs.io/#how-it-works for more info.

or something like this:

AttributeError: 'Flask' object has no attribute 'login_manager'

or others.

the linelogin_manager.init_app(app) is the key here.