Introduction to Django · Django

Django is a Python web framework: a toolkit for building websites and web APIs. It was created in 2005 at a newspaper, and it powers Instagram, Pinterest, Mozilla, Disqus and thousands more.

Batteries included

Django ships with the pieces most websites need, ready to use:

an ORM to work with databases using Python instead of SQL,
an automatic admin site for managing your data,
URL routing, templates and forms,
user accounts and authentication,
strong security defaults: protection against SQL injection, cross-site scripting (XSS), cross-site request forgery (CSRF) and clickjacking.

Its ORM works with these databases out of the box:

Database	Typical use
PostgreSQL	a popular choice in production
MySQL · MariaDB	widely available on web hosts
SQLite	the default for new projects: one file, no server
Oracle	large organisations

How a request flows

Diagram

Browser requests /courses/
   → urls.py   matches the URL to a view
   → views.py  the view gets data (through models) and picks a template
   → models.py the ORM queries the database
   → template  fills HTML with the data
   ← the browser receives the finished HTML page

The URL picks a view; the view asks models for data and hands it to a template; the rendered HTML goes back to the browser.

Models, views, templates (MVT)

Part	Job	File
Model	the data and the rules for it; one class per database table	`models.py`
View	handles a request and returns a response	`views.py`
Template	the HTML, with placeholders for data	`templates/*.html`

Many frameworks call this pattern MVC; Django's "view" plays the controller's role, and the template is the view.

A taste of Django code

A model:

Python

from django.db import models

class Course(models.Model):
    title = models.CharField(max_length=100)
    lessons = models.PositiveIntegerField(default=0)
    published = models.BooleanField(default=True)

    def __str__(self):
        return self.title

A view that lists published courses:

Python

from django.shortcuts import render
from .models import Course

def course_list(request):
    courses = Course.objects.filter(published=True).order_by("title")
    return render(request, "courses/list.html", {"courses": courses})

That's real, complete Django code. The following lessons build up to it step by step.