Backend frameworks

Django & Flask

Python's two big web frameworks. Django is "batteries-included" with an ORM, admin and auth out of the box; Flask is a tiny, flexible micro-framework you grow piece by piece.

Demo 01

Flask: a route returns a response

Flask maps a URL to a Python function with the @app.route decorator. Type a path and "request" it — the simulated dev server matches a view and replies.

Routes: /, /hello/<name>, /api/time

from flask import Flask, jsonify
app = Flask(__name__)

@app.route('/hello/<name>')
def hello(name):
    return f'Hello, {name}!'

@app.route('/api/time')
def api_time():
    return jsonify(time='12:00:00')

Demo 02

Django ORM → SQL → result table

Django's ORM turns Python method chains into SQL. Pick a queryset and watch the simulated Article table respond — plus the SQL Django would generate.

Demo 03

Django models & migrations

You describe your data as a Python class; Django generates the database schema. Click to run makemigrations + migrate and watch it work.

# blog/models.py
class Article(models.Model):
    title   = models.CharField(max_length=200)
    status  = models.CharField(max_length=20)
    views   = models.IntegerField(default=0)
    created = models.DateTimeField(auto_now_add=True)

Demo 04

The famous Django admin

Just one line in admin.py:

admin.site.register(Article)

→ generates this admin list view:

Demo 05

Django vs Flask

Same language, opposite philosophies.

Django

Full-stack & opinionated. ORM, admin, auth, forms and templates included. Great for content sites, dashboards and large teams that want convention.

Flask

Minimal & flexible. Start with just routing; add an ORM (SQLAlchemy), forms etc. only when you need them. Great for small APIs and microservices.

The Flask route console, Django ORM table, migration runner and admin preview are simulated with vanilla JavaScript — real Django & Flask run Python on a server (WSGI/ASGI) with a real database. The code blocks show genuine Python/Django/Flask syntax. The shared CSS shell provides page styling.

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