Examples of Creating RESTful APIs with Flask

Introduction to Creating RESTful APIs with Flask

Building RESTful APIs with Flask is a straightforward and rewarding process. Flask is a micro web framework for Python that allows you to create web applications quickly and efficiently. RESTful APIs enable different software applications to communicate with each other over the web. In this guide, we will explore three diverse and practical examples of creating RESTful APIs with Flask, suitable for developers of all levels.

Example 1: Creating a Simple Todo List API

Context

Imagine you want to build a simple API for a todo list application. This API will allow users to create, read, update, and delete tasks in their todo list.

from flask import Flask, jsonify, request

app = Flask(__name__)

## Sample data
todos = [{"id": 1, "task": "Learn Flask", "done": False}]

@app.route('/todos', methods=['GET'])
def get_todos():
    return jsonify(todos)

@app.route('/todos', methods=['POST'])
def add_todo():
    new_todo = request.get_json()
    todos.append(new_todo)
    return jsonify(new_todo), 201

@app.route('/todos/<int:todo_id>', methods=['PUT'])
def update_todo(todo_id):
    todo = next((todo for todo in todos if todo['id'] == todo_id), None)
    if todo:
        todo.update(request.get_json())
        return jsonify(todo)
    return jsonify({'error': 'Todo not found'}), 404

@app.route('/todos/<int:todo_id>', methods=['DELETE'])
def delete_todo(todo_id):
    global todos
    todos = [todo for todo in todos if todo['id'] != todo_id]
    return '', 204

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

Notes

• This example uses a simple in-memory list to store todo items. In a production environment, you would typically use a database.
• You can test the API using tools like Postman or CURL to send GET, POST, PUT, and DELETE requests.

Example 2: User Authentication API

Context

In many applications, you need to handle user authentication. This example demonstrates how to create a simple user authentication API using Flask that allows users to register and log in.

from flask import Flask, request, jsonify
from werkzeug.security import generate_password_hash, check_password_hash

app = Flask(__name__)
users = {}

@app.route('/register', methods=['POST'])
def register():
    username = request.json['username']
    password = request.json['password']
    if username in users:
        return jsonify({'message': 'User already exists!'}), 400
    users[username] = generate_password_hash(password)
    return jsonify({'message': 'User registered successfully!'}), 201

@app.route('/login', methods=['POST'])
def login():
    username = request.json['username']
    password = request.json['password']
    if username not in users or not check_password_hash(users[username], password):
        return jsonify({'message': 'Invalid credentials!'}), 401
    return jsonify({'message': 'Login successful!'}), 200

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

Notes

• This example uses werkzeug.security for password hashing, ensuring that the passwords are stored securely.
• For a real application, consider using JWT (JSON Web Tokens) for secure token-based authentication.

Example 3: Book Inventory API with Filtering

Context

Suppose you’re building an API for a book inventory where users can browse books and filter them based on categories. This example showcases how to create such an API with Flask.

from flask import Flask, jsonify, request

app = Flask(__name__)

## Sample data
books = [
    {"id": 1, "title": "Flask for Beginners", "category": "Programming"},
    {"id": 2, "title": "Python 101", "category": "Programming"},
    {"id": 3, "title": "Cooking Basics", "category": "Cooking"}
]

@app.route('/books', methods=['GET'])
def get_books():
    category = request.args.get('category')
    if category:
        filtered_books = [book for book in books if book['category'].lower() == category.lower()]
        return jsonify(filtered_books)
    return jsonify(books)

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

Notes

• This API allows users to filter books by category using query parameters. For example, accessing /books?category=Programming will return only programming books.
• You can expand this example by adding more features such as pagination or sorting.

By following these examples of creating RESTful APIs with Flask, you can start building your own web applications with ease. Remember to experiment and modify the code to fit your specific use cases!