Blueprint best practices in Flask - Mini Project: Build & Apply

Blueprint Best Practices in Flask

📖 Scenario: You are building a simple Flask web application that has two parts: a main page and a user page. To keep your code organized, you will use Flask Blueprints to separate these parts.

🎯 Goal: Create two Flask Blueprints named main_bp and user_bp. Register them in the Flask app with URL prefixes. Each Blueprint should have one route that returns a simple message.

📋 What You'll Learn

Create a Flask app instance named app

Create a Blueprint named main_bp with the name 'main' and import name __name__

Create a Blueprint named user_bp with the name 'user' and import name __name__

Add a route / to main_bp that returns the string 'Welcome to the main page!'

Add a route /profile to user_bp that returns the string 'User profile page'

Register main_bp with the Flask app with URL prefix '' (no prefix)

Register user_bp with the Flask app with URL prefix /user

💡 Why This Matters

🌍 Real World

Blueprints help organize large Flask apps by grouping related routes and code, making the app easier to maintain.

💼 Career

Understanding Blueprints is essential for backend developers working with Flask to build scalable and clean web applications.

1

Create the Flask app and main Blueprint

Import Flask and Blueprint from flask. Create a Flask app instance called app. Create a Blueprint called main_bp with the name 'main' and import name __name__.

Flask

from flask import Flask, Blueprint

# Create the Flask app instance
# Your code here

Need a hint?

Use app = Flask(__name__) to create the app. Use Blueprint('main', __name__) to create the main blueprint.

2

Create the user Blueprint

Create a Blueprint called user_bp with the name 'user' and import name __name__.

Flask

from flask import Flask, Blueprint

app = Flask(__name__)

main_bp = Blueprint('main', __name__)

# Create the user blueprint
# Your code here

Need a hint?

Use Blueprint('user', __name__) to create the user blueprint.

3

Add routes to the Blueprints

Add a route / to main_bp that returns the string 'Welcome to the main page!'. Add a route /profile to user_bp that returns the string 'User profile page'.

Flask

from flask import Flask, Blueprint

app = Flask(__name__)

main_bp = Blueprint('main', __name__)

user_bp = Blueprint('user', __name__)

# Add route to main_bp
# Your code here

# Add route to user_bp
# Your code here

Need a hint?

Use @main_bp.route('/') and @user_bp.route('/profile') decorators to add routes.

4

Register Blueprints with the Flask app

Register main_bp with the Flask app using app.register_blueprint(main_bp, url_prefix=''). Register user_bp with the Flask app using app.register_blueprint(user_bp, url_prefix='/user').

Flask

from flask import Flask, Blueprint

app = Flask(__name__)

main_bp = Blueprint('main', __name__)

user_bp = Blueprint('user', __name__)

@main_bp.route('/')
def main_index():
    return 'Welcome to the main page!'

@user_bp.route('/profile')
def user_profile():
    return 'User profile page'

# Register the blueprints with the app
# Your code here

Need a hint?

Use app.register_blueprint() to connect blueprints to the app with the correct URL prefixes.