APIs & the Web

# This example demonstrates a basic RESTful API for managing a collection of books.
# It uses Flask, a lightweight Python web framework, to handle HTTP requests.

from flask import Flask, jsonify, request, abort

app = Flask(__name__)

# Sample data: a list of books represented as dictionaries
books = [
    {'id': 1, 'title': '1984', 'author': 'George Orwell'},
    {'id': 2, 'title': 'To Kill a Mockingbird', 'author': 'Harper Lee'},
]

@app.route('/books', methods=['GET'])
def get_books():
    # Return the list of books as JSON
    return jsonify(books)

@app.route('/books/', methods=['GET'])
def get_book(book_id):
    # Find a book by id
    book = next((b for b in books if b['id'] == book_id), None)
    if book is None:
        abort(404, description="Book not found")
    return jsonify(book)

@app.route('/books', methods=['POST'])
def create_book():
    # Create a new book from JSON payload
    if not request.json or 'title' not in request.json or 'author' not in request.json:
        abort(400, description="Missing title or author")
    new_book = {
        'id': books[-1]['id'] + 1 if books else 1,
        'title': request.json['title'],
        'author': request.json['author']
    }
    books.append(new_book)
    return jsonify(new_book), 201

@app.route('/books/', methods=['PUT'])
def update_book(book_id):
    # Update an existing book
    book = next((b for b in books if b['id'] == book_id), None)
    if book is None:
        abort(404, description="Book not found")
    if not request.json:
        abort(400, description="No data provided")
    book['title'] = request.json.get('title', book['title'])
    book['author'] = request.json.get('author', book['author'])
    return jsonify(book)

@app.route('/books/', methods=['DELETE'])
def delete_book(book_id):
    # Delete a book by id
    global books
    books = [b for b in books if b['id'] != book_id]
    return '', 204

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

# This example shows how to consume the public JSONPlaceholder API to fetch posts using Python's requests library.

import requests

def fetch_posts():
    url = 'https://jsonplaceholder.typicode.com/posts'
    response = requests.get(url)
    if response.status_code == 200:
        posts = response.json()  # Parse JSON response
        for post in posts[:5]:    # Print first 5 posts
            print(f"Post {post['id']}: {post['title']}")
    else:
        print(f"Failed to retrieve posts: {response.status_code}")

if __name__ == '__main__':
    fetch_posts()
    

# This example demonstrates how to secure a Flask API using JWT (JSON Web Tokens) for authentication.

from flask import Flask, jsonify, request
from flask_jwt_extended import (
    JWTManager, create_access_token,
    jwt_required, get_jwt_identity
)

app = Flask(__name__)
app.config['JWT_SECRET_KEY'] = 'super-secret-key'  # Change this in production

jwt = JWTManager(app)

# Simple user datastore
users = {
    'alice': 'password123',
    'bob': 'mypassword'
}

@app.route('/login', methods=['POST'])
def login():
    # Authenticate user and return access token
    if not request.is_json:
        return jsonify({"msg": "Missing JSON in request"}), 400

    username = request.json.get('username', None)
    password = request.json.get('password', None)
    if not username or not password:
        return jsonify({"msg": "Missing username or password"}), 400

    if users.get(username) != password:
        return jsonify({"msg": "Bad username or password"}), 401

    access_token = create_access_token(identity=username)
    return jsonify(access_token=access_token), 200

@app.route('/protected', methods=['GET'])
@jwt_required()
def protected():
    # Access protected route with valid token
    current_user = get_jwt_identity()
    return jsonify(logged_in_as=current_user), 200

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