This allows seamless integration of GraphQL with Flask for handling API requests efficiently.
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Flask is a lightweight micro web framework for Python that allows developers to build web applications quickly and efficiently. It is designed to be simple, flexible, and extensible.
Run the following command in your terminal:
pip install flask
from flask import Flask
app = Flask(__name__)
@app.route('/')
def home():
return "Hello, Flask!"
if __name__ == '__main__':
app.run(debug=True)Run the script, and visit http://127.0.0.1:5000/ in your browser.
The @app.route() decorator is used to define URL routes that map to specific view functions.
Use dynamic route parameters:
@app.route('/user/<name>')
def user(name):
return f"Hello, {name}!"
Use request.form:
from flask import request
@app.route('/submit', methods=['POST'])
def submit():
name = request.form['name']
return f"Hello, {name}!"
Blueprints allow you to organize a Flask application into reusable modules.
app.run(debug=True)
It is an ORM extension for Flask that simplifies database interactions.
from flask_sqlalchemy import SQLAlchemy
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///database.db'
db = SQLAlchemy(app)
It is used for handling web forms in Flask with CSRF protection.
Use Flask's session object:
from flask import session
@app.route('/set_session')
def set_session():
session['user'] = 'John'
return "Session set!"
Use Flask’s request.files:
file = request.files['file']
file.save('uploads/' + file.filename)
Use Flask-Login or JWT for authentication.
Jinja2 is a template engine used in Flask to embed dynamic data in HTML.
from flask import jsonify
@app.route('/api/data')
def api():
return jsonify({"message": "Hello, API!"})
Use @app.errorhandler():
@app.errorhandler(404)
def not_found(error):
return "Page not found", 404
Use before_request and after_request hooks.
You can deploy Flask using Gunicorn, uWSGI, or Docker.
Use Flask-CORS extension.
Use Flask-SocketIO for real-time communication.
Use BluePrints, Caching, Load Balancing, and Microservices.
Use Celery for task scheduling.
Use Flask’s built-in logging module.
Use Flask-OAuthlib for third-party authentication.
It is an extension that simplifies API development.
Use pytest or Flask’s built-in test client.
Use caching, database indexing, and async processing.
Flask can be used as a backend API, serving JSON data.
Flask follows the WSGI request-response cycle.
Use parameterized queries with SQLAlchemy.
Use Flask-Limiter.
from flask_restful import Resource, Api
api = Api(app)
class HelloWorld(Resource):
def get(self):
return {'message': 'Hello, World!'}
api.add_resource(HelloWorld, '/')
It’s a function that creates and configures an app instance.
Use @app.before_request.
Configure Celery and Flask together for background tasks.
Use async/await with Flask 2.x or Celery for async tasks.
To integrate GraphQL with Flask, you can use the Graphene library along with Flask-GraphQL. Follow these steps:
pip install Flask-GraphQL grapheneDefine a simple GraphQL schema:
import graphene
class Query(graphene.ObjectType):
hello = graphene.String(default_value="Hello, Flask GraphQL!")
schema = graphene.Schema(query=Query)Set up the Flask app and add GraphQL support:
from flask import Flask
from flask_graphql import GraphQLView
app = Flask(__name__)
app.add_url_rule(
"/graphql",
view_func=GraphQLView.as_view("graphql", schema=schema, graphiql=True)
)
app,run(debug=True)
http://127.0.0.1:5000/graphql in a browser to test queries using the GraphiQL interface.Flask-Limiter is used to implement rate limiting in Flask applications to prevent abuse.
Example:
from flask import Flask
from flask_limiter import Limiter
app = Flask(__name__)
limiter = Limiter(app)
@app.route('/')
@limiter.limit("5 per minute")
def home():
return "This is rate limited!"
if __name__ == '__main__':
app.run()This limits the route to 5 requests per minute per IP.
To secure a Flask application:
Example using Flask-Talisman:
from flask_talisman import Talisman
app = Flask(__name__)
Talisman(app)This enforces security headers like Content Security Policy (CSP).
You can use Flask-JWT-Extended to implement JWT authentication.
Example:
from flask import Flask, jsonify
from flask_jwt_extended import JWTManager, create_access_token, jwt_required
app = Flask(__name__)
app.config["JWT_SECRET_KEY"] = "super-secret"
jwt = JWTManager(app)
@app.route("/login", methods=["POST"])
def login():
token = create_access_token(identity="user123")
return jsonify(access_token=token)
@app.route("/protected", methods=["GET"])
@jwt_required()
def protected():
return jsonify(message="You are authorized!")
if __name__ == '__main__':
app.run()JWT is used for secure token-based authentication.
You can use Flask-SocketIO for real-time bidirectional communication.
Example:
from flask import Flask
from flask_socketio import SocketIO
app = Flask(__name__)
socketio = SocketIO(app)
@socketio.on('message')
def handle_message(msg):
print("Received:", msg)
if __name__ == '__main__':
socketio.run(app)This allows real-time data exchange without reloading the page.
Use Flask-Mail to send emails.
Example:
from flask_mail import Mail, Message
app.config['MAIL_SERVER'] = 'smtp.gmail.com'
app.config['MAIL_PORT'] = 587
app.config['MAIL_USE_TLS'] = True
app.config['MAIL_USERNAME'] = 'your_email@gmail.com'
app.config['MAIL_PASSWORD'] = 'your_password'
mail = Mail(app)
@app.route('/send_email')
def send_email():
msg = Message("Hello!", sender="your_email@gmail.com", recipients=["recipient@gmail.com"])
msg.body = "This is a test email!"
mail.send(msg)
return "Email sent!"This allows sending emails through SMTP.
Flask-Talisman is a security extension that:
from flask_talisman import Talisman
app = Flask(__name__)
Talisman(app)
You can use Flask-PyMongo to connect Flask with MongoDB.
Example:
from flask_pymongo import PyMongo
app.config["MONGO_URI"] = "mongodb://localhost:27017/myDatabase"
mongo = PyMongo(app)
@app.route('/add')
def add_data():
mongo.db.users.insert_one({"name": "John"})
return "User added!"This allows interaction with MongoDB collections.
Flask-Caching is used for caching responses and reducing database queries.
Example using simple cache:
from flask_caching import Cache
app.config['CACHE_TYPE'] = 'simple'
cache = Cache(app)
@app.route('/data')
@cache.cached(timeout=50)
def get_data():
return "Cached Data"This caches the /data endpoint for 50 seconds.
Celery allows running background tasks asynchronously.
Example:
from celery import Celery
app = Flask(__name__)
celery = Celery(app.name, broker='redis://localhost:6379/0')
@celery.task
def async_task():
return "Task Complete!"This runs background jobs without blocking the main application.
Use Flask’s built-in Flask-Script.
Example:
from flask import Flask
import click
app = Flask(__name__)
@app.cli.command("greet")
@click.argument("name")
def greet(name):
print(f"Hello, {name}!")
if __name__ == '__main__':
app.run()Run in terminal:
flask greet Kartik
Use the following structure for a large-scale Flask project:
/my_flask_app
/app
/static
/templates
/models
/routes
/views
/config.py
/run.py
/requirements.txtThis follows the MVC pattern.
Flask-Migrate is an extension that helps manage database migrations.
Example:
flask db init
flask db migrate -m "Initial Migration"
flask db upgrade
Use Flask’s built-in logging module.
Example:
import logging
logging.basicConfig(filename="app.log", level=logging.DEBUG)
@app.route('/')
def home():
app.logger.info("Home page accessed")
return "Logging Enabled!"
Use Flask-Uploads or chunked uploads.
Example:
@app.route('/upload', methods=['POST'])
def upload():
file = request.files['file']
file.save(f"./uploads/{file.filename}")
return "File uploaded!"
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