API versioning with blueprints in Flask - Mini Project: Build & Apply

API Versioning with Blueprints in Flask

📖 Scenario: You are building a simple web API for a bookstore. You want to support two versions of the API so clients can choose which version to use. You will use Flask blueprints to organize the code for each API version.

🎯 Goal: Create two Flask blueprints named v1 and v2 for API version 1 and version 2. Each blueprint will have a route /books that returns a JSON list of books. Then register both blueprints in the Flask app with URL prefixes /api/v1 and /api/v2.

📋 What You'll Learn

Create a Flask app instance named app

Create a blueprint named v1 with a route /books returning a JSON list of book titles for version 1

Create a blueprint named v2 with a route /books returning a JSON list of book titles for version 2

Register both blueprints on the Flask app with URL prefixes /api/v1 and /api/v2

💡 Why This Matters

🌍 Real World

API versioning is important when you want to improve or change your API without breaking existing clients. Blueprints help organize code for each version cleanly.

💼 Career

Many web developers and backend engineers use Flask blueprints to build scalable APIs that support multiple versions for different clients.

1

Create the Flask app and version 1 blueprint

Create a Flask app instance called app. Then create a blueprint called v1 with the name 'v1' and import name __name__. Add a route /books to v1 that returns a JSON list ["The Great Gatsby", "1984"].

Flask

# Create Flask app instance called app
# Create blueprint v1 with name 'v1' and __name__
# Add route /books to v1 returning JSON list ["The Great Gatsby", "1984"]

Need a hint?

Use Flask(__name__) to create the app. Use Blueprint('v1', __name__) to create the blueprint. Use @v1.route('/books') to add the route. Return the JSON list with jsonify.

2

Create the version 2 blueprint with updated book list

Create a blueprint called v2 with the name 'v2' and import name __name__. Add a route /books to v2 that returns a JSON list ["Brave New World", "Fahrenheit 451"].

Flask

from flask import Flask, Blueprint, jsonify

app = Flask(__name__)

v1 = Blueprint('v1', __name__)

@v1.route('/books')
def books_v1():
    return jsonify(["The Great Gatsby", "1984"])

# Create blueprint v2 with name 'v2' and __name__
# Add route /books to v2 returning JSON list ["Brave New World", "Fahrenheit 451"]

Need a hint?

Create the v2 blueprint like v1. Add the /books route returning the new list of books using jsonify.

3

Register blueprints with URL prefixes

Register the blueprint v1 on the Flask app app with the URL prefix /api/v1. Register the blueprint v2 on app with the URL prefix /api/v2.

Flask

from flask import Flask, Blueprint, jsonify

app = Flask(__name__)

v1 = Blueprint('v1', __name__)

@v1.route('/books')
def books_v1():
    return jsonify(["The Great Gatsby", "1984"])

v2 = Blueprint('v2', __name__)

@v2.route('/books')
def books_v2():
    return jsonify(["Brave New World", "Fahrenheit 451"])

# Register v1 blueprint with prefix /api/v1
# Register v2 blueprint with prefix /api/v2

Need a hint?

Use app.register_blueprint() with the url_prefix argument to register each blueprint.

4

Add app run block for local testing

Add the standard Flask app run block at the bottom: if __name__ == '__main__': then run app.run(debug=True).

Flask

from flask import Flask, Blueprint, jsonify

app = Flask(__name__)

v1 = Blueprint('v1', __name__)

@v1.route('/books')
def books_v1():
    return jsonify(["The Great Gatsby", "1984"])

v2 = Blueprint('v2', __name__)

@v2.route('/books')
def books_v2():
    return jsonify(["Brave New World", "Fahrenheit 451"])

app.register_blueprint(v1, url_prefix='/api/v1')
app.register_blueprint(v2, url_prefix='/api/v2')

# Add app run block here

Need a hint?

Add the standard Flask run block to start the server locally with debugging enabled.