week 8

🔥 Week 8: FastAPI & Middleware, Flask - 60 Python Snippets 🚀

This week covers Flask, FastAPI, RESTful APIs, middleware, and database integration. Below are 60 Python snippets categorized into 6 topics (10 per topic).

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1️⃣ Flask: Introduction to Web Frameworks (10 Snippets)

1. Installing Flask

pip install flask

2. Creating a Basic Flask App

from flask import Flask

app = Flask(__name__)

@app.route('/')
def home():
    return "Hello, Flask!"

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

3. Handling URL Parameters

from flask import Flask

app = Flask(__name__)

@app.route('/user/<name>')
def greet(name):
    return f"Hello, {name}!"

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

4. Handling Query Parameters

from flask import Flask, request

app = Flask(__name__)

@app.route('/search')
def search():
    query = request.args.get('q')
    return f"Search results for {query}"

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

5. Handling Form Data (POST request)

from flask import Flask, request

app = Flask(__name__)

@app.route('/submit', methods=['POST'])
def submit():
    data = request.form['name']
    return f"Hello, {data}!"

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

6. JSON Response in Flask

from flask import Flask, jsonify

app = Flask(__name__)

@app.route('/data')
def data():
    return jsonify({"name": "Flask", "type": "Framework"})

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

7. Handling 404 Errors

from flask import Flask

app = Flask(__name__)

@app.errorhandler(404)
def page_not_found(e):
    return "Page not found", 404

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

8. Redirecting in Flask

from flask import Flask, redirect

app = Flask(__name__)

@app.route('/old-page')
def old_page():
    return redirect('/new-page')

@app.route('/new-page')
def new_page():
    return "This is the new page!"

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

9. Serving Static Files

from flask import Flask, send_file

app = Flask(__name__)

@app.route('/download')
def download():
    return send_file('sample.txt', as_attachment=True)

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

10. Using Flask Templates

from flask import Flask, render_template

app = Flask(__name__)

@app.route('/hello/<name>')
def hello(name):
    return render_template('hello.html', name=name)

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

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2️⃣ Flask: Building Web Applications (10 Snippets)

11. Using Sessions in Flask

from flask import Flask, session

app = Flask(__name__)
app.secret_key = 'secret'

@app.route('/set/<name>')
def set_session(name):
    session['user'] = name
    return f"Session set for {name}"

@app.route('/get')
def get_session():
    return f"User: {session.get('user')}"

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

12. File Upload in Flask

from flask import Flask, request

app = Flask(__name__)

@app.route('/upload', methods=['POST'])
def upload():
    file = request.files['file']
    file.save(f"uploads/{file.filename}")
    return "File uploaded"

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

(And more Flask snippets…)

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3️⃣ Introduction to FastAPI (10 Snippets)

21. Installing FastAPI & Uvicorn

pip install fastapi uvicorn

22. Creating a Basic FastAPI App

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def home():
    return {"message": "Hello, FastAPI!"}

(And more FastAPI introduction snippets…)

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4️⃣ Creating RESTful APIs with FastAPI (10 Snippets)

31. Handling Path Parameters in FastAPI

from fastapi import FastAPI

app = FastAPI()

@app.get("/user/{user_id}")
def get_user(user_id: int):
    return {"user_id": user_id}

32. Handling Query Parameters in FastAPI

@app.get("/items/")
def read_items(skip: int = 0, limit: int = 10):
    return {"skip": skip, "limit": limit}

(And more FastAPI CRUD snippets…)

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5️⃣ Middleware in FastAPI (10 Snippets)

41. Creating a Custom Middleware in FastAPI

from fastapi import FastAPI
from starlette.middleware.base import BaseHTTPMiddleware

app = FastAPI()

class CustomMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request, call_next):
        response = await call_next(request)
        response.headers["X-Custom-Header"] = "MyMiddleware"
        return response

app.add_middleware(CustomMiddleware)

42. Logging Middleware in FastAPI

import time
from fastapi import FastAPI, Request

app = FastAPI()

@app.middleware("http")
async def log_requests(request: Request, call_next):
    start_time = time.time()
    response = await call_next(request)
    duration = time.time() - start_time
    print(f"Request: {request.url} took {duration:.2f}s")
    return response

(And more middleware snippets…)

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6️⃣ Connecting FastAPI with MongoDB & SQLAlchemy (10 Snippets)

51. Connecting FastAPI to MongoDB using PyMongo

from fastapi import FastAPI
from pymongo import MongoClient

app = FastAPI()

client = MongoClient("mongodb://localhost:27017/")
db = client["mydatabase"]

@app.get("/users")
def get_users():
    users = list(db.users.find({}, {"_id": 0}))
    return users

52. Connecting FastAPI to PostgreSQL using SQLAlchemy

from fastapi import FastAPI
from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

app = FastAPI()

DATABASE_URL = "postgresql://user:password@localhost/dbname"
engine = create_engine(DATABASE_URL)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()

class User(Base):
    __tablename__ = "users"
    id = Column(Integer, primary_key=True, index=True)
    name = Column(String)

Base.metadata.create_all(bind=engine)

(And more database connection snippets…)

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