Blueprints

A Love Story

What's a Blueprint?

Blueprints are the recommended way to implement larger or more pluggable applications in Flask 0.7 and later.

Source: Flask source code

What's a Blueprint?

A Blueprint object works similarly to a Flask application object, but it is not actually an application. Rather it is a blueprint of how to construct or extend an application.

Source: Flask docs

What's a Blueprint?

Blueprints are "subapplications" that encapsulate related logic and the only way to sanely grow an application.

Source: Me

An Analogy to Django

Flask Application ≅ Django Project

Blueprint ≅ Django Application

Why Use Blueprints?

Portable and reusable code
Encourages manageable project structure
Makes your code DRYer

How Flask Applications Grow

A single file containing most of your application code

How Flask Applications Grow

A few files representing your MVC structure

How Flask Applications Grow

Blueprints!

Models, views, and templates for each Blueprint
Blueprints get reused between applications

Examples

The official large app how to
Matt Wright's notes and examples on the subject

Converting Your Code

Change this:

from ..core import app

...

@app.route('/users/')
def user_list():
    ...

Converting Your Code

To this:

from flask import Blueprint

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

...

@bp.route('/')
def user_list():
    ...

Converting Your Code

And add this:

from .users.views import bp as user_bp

...

app.register_blueprint(user_bp, url_prefix='/users')

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Blueprints

What's a Blueprint?

What's a Blueprint?

What's a Blueprint?

An Analogy to Django

Why Use Blueprints?

How Flask Applications Grow

How Flask Applications Grow

How Flask Applications Grow

Examples

Converting Your Code

Converting Your Code

Converting Your Code

Considerations

Blueprints All The Way Down

FIN.