How to get current user when implementing Python Flask-Security?

Question

I am using Flask-Security to set up user authentication for my app but I am struggling with getting the email address or ID of the currently logged in user so I can query a table with that particular users details. I've just using the standard code.

Another question here suggested the following but it didn't work:

my_user = current_user.get_id()

Standard code:

from flask import Flask, render_template
from flask_sqlalchemy import SQLAlchemy
from flask_security import Security, SQLAlchemyUserDatastore, \
    UserMixin, RoleMixin, login_required

# Create app
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SECRET_KEY'] = 'super-secret'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite://'

# Create database connection object
db = SQLAlchemy(app)

# Define models
roles_users = db.Table('roles_users',
        db.Column('user_id', db.Integer(), db.ForeignKey('user.id')),
        db.Column('role_id', db.Integer(), db.ForeignKey('role.id')))

class Role(db.Model, RoleMixin):
    id = db.Column(db.Integer(), primary_key=True)
    name = db.Column(db.String(80), unique=True)
    description = db.Column(db.String(255))

class User(db.Model, UserMixin):
    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.String(255), unique=True)
    password = db.Column(db.String(255))
    active = db.Column(db.Boolean())
    confirmed_at = db.Column(db.DateTime())
    roles = db.relationship('Role', secondary=roles_users,
                            backref=db.backref('users', lazy='dynamic'))

# Setup Flask-Security
user_datastore = SQLAlchemyUserDatastore(db, User, Role)
security = Security(app, user_datastore)

# Create a user to test with
@app.before_first_request
def create_user():
    db.create_all()
    user_datastore.create_user(email='[email protected]', password='password')
    db.session.commit()

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

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

Dallas

Answer 1

You can use flask_login.current_user object. Its class will be what you configured Flask-Security to use to handle your users management, e.g. User for code you included.

Rowel

Could you explain how I can print the current user to the terminal in the case of above? I have tried print(flask_login.current_user) and print(User.current_user) etc but cannot seem to get the current user using your method. – Dallas

It's not 'my method'. It's an object built into flask_login module, which is automatically set up by Flask-Security. Did you import flask_login before trying to print out flask_login.current user? – Rowel

I followed the flask-security quickstart, which recommended creating the User class in a models.py file. In my app.py file, I could import flask_login, then refer to flask_login.current_user.email as @Rowel described. The current_user is an instance of the User class I defined in models.py. – Stantonstanway

Where do you import flask_login from? Ah I see it in another comment. It would be good to add this to your answer itself. – Waldron

Answer 2

Michael was half right, the issue is that the standard code example does not import sessions and whilst flask-security does in the back end set the session, it's not available in your flask app. This code from Michael:

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        session['username'] = request.form['username']
        session['email'] = request.form['email']

Whilst correct in a standard app would likely break with flask-security or at least be unnecessary as flask-security completely takes control of the /login route and handles the form securely. The only two changes needed to the flask example app are:

Changing the flask import line to:

from flask import Flask, render_template, session

This is an example of getting the user id from the session:

@app.route('/dashboard')
@login_required
def dashboard():
    user_id = session["user_id"]
    return name

Hope this helps someone as it took me a while to get my head around..

Dallas

If I wanted to add something to the session at login, other than just fresh and user_id (like username), what's the best way to do that? If I take the route, I break flask-security stuff. – Jacobba

Answer 3

IMHO you can implement sessions from Flask.

from flask import Flask, session, redirect, url_for, escape, request

app = Flask(__name__)

@app.route('/')
def index():
    if 'username' in session:
        print("Currents user's ID is %s" % session['id']
        return 'Logged in as %s' % escape(session['username'])
    return 'You are not logged in'

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        session['username'] = request.form['username']
        session['email'] = request.form['email']
        session['id'] = request.form['id']
        return redirect(url_for('index'))
    return '''
        <form method="post">
            <p><input type=text name=username>
            <p><input type=submit value=Login>
        </form>
    '''

@app.route('/logout')
def logout():
    # remove the username from the session if it's there
    session.pop('username', None)
    session.pop('email', None)
    session.pop('id', None)
    return redirect(url_for('index'))

# set the secret key.  keep this really secret:
app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT'

See: http://flask.pocoo.org/docs/0.12/quickstart/#sessions

Fault

Answer 4

In flask 2.0.x user id is automaticly saved in session under _user_id, not sure how or where this changed, in the official flask docs it still uses g.user, but maybe its outdated? I couldnt get it to work for me.

The simplest way i could get it to check if a user was login in with if '_user_id' in sessions.keys(), the return value of session['_user_id'] is a string of User.id

Galba

Answer 5

Its better to use session for this. You can store the information is session then use it anywhere.

In your login function just store the value like: first import the session from flask.Then use like this.

session['username'] = login_form.username.data

then use it like {{ session['username'] }} in your template.

Glabrescent

Is this recommended for flask security because it takes care of all of the user login management. What I don’t want to do is build functionality that already exists. – Dallas