User Authentication
User authentication allows users to register, log in, and log out. Flask‑Login manages sessions and protects routes.
Installing Flask‑Login
pip install flask-loginSetting Up Flask‑Login
from flask_login import LoginManager, UserMixin, login_user, current_user, logout_user, login_required
login_manager = LoginManager(app)
login_manager.login_view = 'login'
@login_manager.user_loader
def load_user(user_id):
return User.query.get(int(user_id))Update User Model (Inherit UserMixin)
class User(db.Model, UserMixin):
# existing columns...Registration Route
Hash the password using `werkzeug.security` before storing.
from werkzeug.security import generate_password_hash
hashed_pw = generate_password_hash(password, method='sha256')
new_user = User(username=username, email=email, password=hashed_pw)
db.session.add(new_user)
db.session.commit()Login Route
from werkzeug.security import check_password_hash
@app.route('/login', methods=['GET', 'POST'])
def login():
# ...
user = User.query.filter_by(email=email).first()
if user and check_password_hash(user.password, password):
login_user(user)
return redirect(url_for('home'))
# ...Logout and Protected Routes
@app.route('/logout')
@login_required
def logout():
logout_user()
return redirect(url_for('home'))Two Minute Drill
- Flask‑Login manages user sessions.
- User model must inherit `UserMixin`.
- Hash passwords with `generate_password_hash`.
- Use `login_user()` and `logout_user()` for session control.
- Protect routes with `@login_required`.
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