In this section, we will explore how to build RESTful APIs using the Flask framework. REST (Representational State Transfer) is an architectural style that uses HTTP requests to access and manipulate data. Flask is a lightweight WSGI web application framework in Python that is easy to use and well-suited for building APIs.

By the end of this section, you will be able to:

• Understand the basics of RESTful APIs.
• Set up a Flask application for building APIs.
• Create endpoints for CRUD (Create, Read, Update, Delete) operations.
• Handle JSON data in Flask.
• Implement error handling in your API.

Before starting this section, ensure you have:

• Basic knowledge of Flask (covered in the previous section).
• Python installed on your machine.
• Flask installed (pip install Flask).

• Resource: Any piece of data that can be named and manipulated, such as a user, a blog post, or a product.
• Endpoint: A specific URL where a resource can be accessed.
• HTTP Methods: The actions you can perform on a resource (GET, POST, PUT, DELETE).
• Status Codes: Standardized codes that indicate the result of an HTTP request (e.g., 200 OK, 404 Not Found).

1. Create a Project Directory:

   mkdir flask_api
   cd flask_api
   

2. Set Up a Virtual Environment:

   python -m venv venv
   source venv/bin/activate  # On Windows use `venv\Scripts\activate`
   

3. Install Flask:

   pip install Flask
   

4. Create the Flask Application:

   # app.py
   from flask import Flask, jsonify, request
   
   app = Flask(__name__)
   
   @app.route('/')
   def home():
       return "Welcome to the Flask REST API!"
   
   if __name__ == '__main__':
       app.run(debug=True)
   

5. Run the Application:

   python app.py
   

1. Define the User Resource:

   users = [
       {'id': 1, 'name': 'John Doe', 'email': '[email protected]'},
       {'id': 2, 'name': 'Jane Doe', 'email': '[email protected]'}
   ]
   

2. Create Endpoints:

   • GET /api/users: Retrieve all users

     @app.route('/api/users', methods=['GET'])
     def get_users():
         return jsonify(users)
     

   • GET /api/users/{id}: Retrieve a specific user

     @app.route('/api/users/<int:user_id>', methods=['GET'])
     def get_user(user_id):
         user = next((user for user in users if user['id'] == user_id), None)
         if user:
             return jsonify(user)
         return jsonify({'message': 'User not found'}), 404
     

   • POST /api/users: Create a new user

     @app.route('/api/users', methods=['POST'])
     def create_user():
         new_user = request.get_json()
         new_user['id'] = len(users) + 1
         users.append(new_user)
         return jsonify(new_user), 201
     

   • PUT /api/users/{id}: Update a specific user

     @app.route('/api/users/<int:user_id>', methods=['PUT'])
     def update_user(user_id):
         user = next((user for user in users if user['id'] == user_id), None)
         if user:
             data = request.get_json()
             user.update(data)
             return jsonify(user)
         return jsonify({'message': 'User not found'}), 404
     

   • DELETE /api/users/{id}: Delete a specific user

     @app.route('/api/users/<int:user_id>', methods=['DELETE'])
     def delete_user(user_id):
         global users
         users = [user for user in users if user['id'] != user_id]
         return jsonify({'message': 'User deleted'})
     

Create a Flask API for managing a list of books. Each book should have an id, title, author, and published_date.

1. Set up the Flask application.
2. Create endpoints for CRUD operations:
   • GET /api/books
   • GET /api/books/{id}
   • POST /api/books
   • PUT /api/books/{id}
   • DELETE /api/books/{id}

In this section, you learned how to build RESTful APIs using Flask. You now know how to:

• Set up a Flask application for API development.
• Create endpoints for CRUD operations.
• Handle JSON data in Flask.
• Implement error handling in your API.

In the next section, we will explore how to integrate databases with Flask to persist data.