CodeToLive

Essential Flask Extensions

Flask's extensibility is one of its greatest strengths. Here are some essential extensions that add powerful functionality to your Flask applications.

Flask-SQLAlchemy (Database ORM)


from flask_sqlalchemy import SQLAlchemy

app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///site.db'
db = SQLAlchemy(app)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(20), unique=True, nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)
    password = db.Column(db.String(60), nullable=False)

    def __repr__(self):
        return f"User('{self.username}', '{self.email}')"

Flask-Migrate (Database Migrations)


# Initialize migrations
flask db init

# Create migration
flask db migrate -m "Initial migration"

# Apply migration
flask db upgrade

Flask-WTF (Forms)


from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, SubmitField
from wtforms.validators import DataRequired, Length, Email, EqualTo

class RegistrationForm(FlaskForm):
    username = StringField('Username', 
                          validators=[DataRequired(), Length(min=2, max=20)])
    email = StringField('Email',
                       validators=[DataRequired(), Email()])
    password = PasswordField('Password', validators=[DataRequired()])
    confirm_password = PasswordField('Confirm Password',
                                    validators=[DataRequired(), EqualTo('password')])
    submit = SubmitField('Sign Up')

Flask-Login (Authentication)


from flask_login import LoginManager, login_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))

@app.route('/login', methods=['GET', 'POST'])
def login():
    if form.validate_on_submit():
        user = User.query.filter_by(email=form.email.data).first()
        if user and bcrypt.check_password_hash(user.password, form.password.data):
            login_user(user, remember=form.remember.data)
            return redirect(url_for('home'))

Flask-Mail (Email Support)


from flask_mail import Mail, Message

app.config['MAIL_SERVER'] = 'smtp.googlemail.com'
app.config['MAIL_PORT'] = 587
app.config['MAIL_USE_TLS'] = True
app.config['MAIL_USERNAME'] = os.environ.get('EMAIL_USER')
app.config['MAIL_PASSWORD'] = os.environ.get('EMAIL_PASS')

mail = Mail(app)

msg = Message('Password Reset Request',
              sender='noreply@demo.com',
              recipients=[user.email])
msg.body = f'''To reset your password, visit the following link:
{url_for('reset_token', token=token, _external=True)}
'''
mail.send(msg)

Flask-RESTful (API Development)


from flask_restful import Resource, Api

api = Api(app)

class HelloWorld(Resource):
    def get(self):
        return {'hello': 'world'}

api.add_resource(HelloWorld, '/api')

Other Useful Extensions

Next: RESTful APIs