Blueprint routes and templates in Flask

Introduction

Blueprints help organize your Flask app by grouping routes and templates. They make your code cleaner and easier to manage.

You want to split a big app into smaller parts like user, admin, and blog sections.

You want to reuse routes and templates in different projects.

You want to keep your code organized when working with a team.

You want to load templates specific to a part of your app.

You want to avoid cluttering the main app file with many routes.

Syntax

Flask

from flask import Blueprint, render_template

bp = Blueprint('bp_name', __name__, template_folder='templates')

@bp.route('/path')
def view_func():
    return render_template('template.html')

The first argument is the blueprint's name, used internally.

template_folder tells Flask where to find templates for this blueprint.

Examples

This blueprint handles user-related routes and templates.

Flask

from flask import Blueprint, render_template

user_bp = Blueprint('user', __name__, template_folder='user_templates')

@user_bp.route('/profile')
def profile():
    return render_template('profile.html')

This blueprint is for admin routes and templates.

Flask

from flask import Blueprint, render_template

admin_bp = Blueprint('admin', __name__, template_folder='admin_templates')

@admin_bp.route('/dashboard')
def dashboard():
    return render_template('dashboard.html')

Sample Program

This example creates a blueprint named 'simple' with one route '/hello'. The blueprint is registered with the app under the URL prefix '/bp'. When you visit '/bp/hello', it shows a message from the blueprint.

Flask

from flask import Flask, Blueprint, render_template_string

app = Flask(__name__)

# Create a blueprint
bp = Blueprint('simple', __name__, template_folder='templates')

# Define a route in the blueprint
@bp.route('/hello')
def hello():
    # Use a simple template string for demo
    return render_template_string('<h1>Hello from Blueprint!</h1>')

# Register the blueprint with the app
app.register_blueprint(bp, url_prefix='/bp')

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

Important Notes

Always register your blueprint with the main app using app.register_blueprint().

Use url_prefix to add a common path before all blueprint routes.

Blueprint templates can be stored in a separate folder to keep things tidy.

Summary

Blueprints group routes and templates to organize your Flask app.

Register blueprints with the main app to activate their routes.

Use url_prefix to avoid route conflicts and keep URLs clear.