Part of Flask Tutorial: Learn how to structure your Flask project and compare the pros and cons between different options.
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👉 This structure is recommended for simple projects and DEMO's where we need to code simple apps fast.
# Simple, one file Flask App
from flask import Flask
app = Flask(__name__)
@app.route('/')
def hello():
return f'Hello from Flask!'The code will encapsulate routing, configuration, and assets management in the same place. To start the application, we need to export the FLASK_APP variable and invoke flask run.
$ export FLASK_APP=run.py
$ flask runOur simple app should be accessible in the browser: localhost:5000. By default Flask will start the application using the port 5000 but this can be changed using --port argument:
$ # Flask app will start on 5001
$ flask run --port=5001👉 Once our project is getting bigger we might want to use a better codebase structure. The structure presented below it might be a good choice:
< PROJECT ROOT >
|
|-- app/
| |
| | -- config.py # App Configuration
| | -- models.py # Database Tables
| | -- forms.py # App Forms: login, registration
| | -- util.py # Helpers to manipulate date, files
| | -- views.py # App Routing
| | -- __init__.py # Bundle all above sections and expose the Flask APP
| |
| |-- static/
| | |-- <css, JS, images> # CSS files, Javascripts files
| |
| |-- templates/
| | |
| | |-- includes/ # Page chunks, components
| | | |
| | | |-- navigation.html # Top bar
| | | |-- sidebar.html # Left sidebar
| | | |-- scripts.html # JS scripts common to all pages
| | | |-- footer.html # The common footer
| | |
| | |-- layouts/ # App Layouts (the master pages)
| | | |
| | | |-- base.html # Used by common pages like index, UI
| | |
| | |-- accounts/ # Auth Pages (login, register)
| | | |
| | | |-- login.html # Use layout `base-fullscreen.html`
| | | |-- register.html # Use layout `base-fullscreen.html`
| | |
| | index.html # The default page
| | page-404.html # Error 404 page (page not found)
| | page-500.html # Error 500 page (server error)
| | *.html # All other pages provided by the UI Kit
|
|-- requirements.txt # Application Dependencies
|
|-- run.py # Start the app in development and production
|
|-- ************************************************************************Relevant Files and folders
run.py- is the entry point called to start the appapp/__init__.py- bundle all app sections: configuration, forms, database connection- App modules:
views(routing),config,forms,util - App static assets and template folders:
static: the place where JS,Images and CSS files are savedtemplates: pages and components to be used
To visualize samples app that uses this structure please visit the Sample Apps section.
👉 Flask uses Blueprints concept for a modular, easy to extend app structure. Bleuprints, similar to Django apps are basically modules that implement specific features. A Blueprint sample migth be the authentication module or a module that handles user notifications via email or SMS.
Using Blueprints is ideal to large projects like eCommerce projects for instance. Here is a sample extracted from the official docs:
Define a Blueprint
from flask import Blueprint, render_template, abort
from jinja2 import TemplateNotFound
# Define the Blueprint
simple_bp = Blueprint( 'simple_bp', __name__,
template_folder='templates')
@simple_page.route('/')
def show(page):
return f'My first Blueprint!'Once we code it, we need to register the blueprint and make it usable.
Register Blueprint
from flask import Flask
from app.simple_bp import simple_bp
app = Flask(__name__)
app.register_blueprint(simple_bp)In this sample, the Blueprint is 'mounted' in the root of the app but we can also use different locations:
app.register_blueprint(simple_bb, url_prefix='/contact')Afer this update, the Blueprint is reachable by accessing /contact path of our application.
Blueprints - A real sample
< PROJECT ROOT >
|
|-- app/ # Implements app logic
| |-- base/ # Base Blueprint - handles the authentication
| |-- home/ # Home Blueprint - serve UI Kit pages
| |
| __init__.py # Initialize the app
|
|-- requirements.txt # Development modules - SQLite storage
|
|-- .env # Inject Configuration via Environment
|-- config.py # Set up the app
|-- run.py # Start the app - WSGI gateway
|
|-- ************************************************************************Relevant Files and folders
run.py- is the entry point that expose ourAPPapp/__init__.py- bundle/constructs the app: register Blueprints, configuration, set up Database- Define
baseblueprint - handles the authentication - Define
homeblueprint - serve the pages to authenticated users - expose
create_app()method - App factory Pattern
App Factory Pattern
This method is usually a good technique to develop complex projects in Flask. A factory pattern exposes the application bundled with all mandatory assets:
- Read Configuration
- Register Blueprints
- Set up the database
- Activate extensions (logging for instance)
To visualize samples app that uses this structure please visit the Sample Apps section.
👉 To visualize mentioned pattern in real-world Flask applications, here is a short-list:
- Flask Swipe - uses the Isolated app directory pattern
- Flask IraDesign - uses the Isolated app directory pattern
- Flask Datta Able - uses the blueprints pattern
Flask Project Structure - Flask Tutorial | by AppSeed.