Intro to Django

Object-relational mapper

Deﬁne your data models entirely in Python. You get a rich, dynamic database-access API for free — but you can still write SQL if needed.

class Band(models.Model):
    """A model of a rock band."""
    name = models.CharField(max_length=200)
    can_rock = models.BooleanField(default=True)


class Member(models.Model):
    """A model of a rock band member."""
    name = models.CharField("Member's name", max_length=200)
    instrument = models.CharField(choices=(
            ('g', "Guitar"),
            ('b', "Bass"),
            ('d', "Drums"),
        ),
        max_length=1
    )
    band = models.ForeignKey("Band")

URLs and views

A clean, elegant URL scheme is an important detail in a high-quality Web application. Django encourages beautiful URL design and doesn’t put any cruft in URLs, like .php or .asp.

To design URLs for an application, you create a Python module called a URLconf. Like a table of contents for your app, it contains a simple mapping between URL patterns and your views.

from django.urls import path

from . import views

urlpatterns = [
    path('bands/', views.band_listing, name='band-list'),
    path('bands/<int:band_id>/', views.band_detail, name='band-detail'),
    path('bands/search/', views.band_search, name='band-search'),
]

from django.shortcuts import render

def band_listing(request):
    """A view of all bands."""
    bands = models.Band.objects.all()
    return render(request, 'bands/band_listing.html', {'bands': bands})

Templates

Django’s template language is designed to strike a balance between power and ease. It’s designed to feel comfortable and easy-to-learn to those used to working with HTML, like designers and front-end developers. But it is also flexible and highly extensible, allowing developers to augment the template language as needed.

<html>
  <head>
    <title>Band Listing</title>
  </head>
  <body>
    <h1>All Bands</h1>
    <ul>
    
    </ul>
  </body>
</html>

Forms

Django provides a powerful form library that handles rendering forms as HTML, validating user-submitted data, and converting that data to native Python types. Django also provides a way to generate forms from your existing models and use those forms to create and update data.

from django import forms

class BandContactForm(forms.Form):
    subject = forms.CharField(max_length=100)
    message = forms.CharField()
    sender = forms.EmailField()
    cc_myself = forms.BooleanField(required=False)

Authentication

Django comes with a full-featured and secure authentication system. It handles user accounts, groups, permissions and cookie-based user sessions. This lets you easily build sites that allow users to create accounts and safely log in/out.

from django.contrib.auth.decorators import login_required
from django.shortcuts import render

@login_required
def my_protected_view(request):
    """A view that can only be accessed by logged-in users"""
    return render(request, 'protected.html', {'current_user': request.user})

Admin

One of the most powerful parts of Django is its automatic admin interface. It reads metadata in your models to provide a powerful and production-ready interface that content producers can immediately use to start managing content on your site. It’s easy to set up and provides many hooks for customization.

from django.contrib import admin
from bands.models import Band, Member

class MemberAdmin(admin.ModelAdmin):
    """Customize the look of the auto-generated admin for the Member model"""
    list_display = ('name', 'instrument')
    list_filter = ('band',)

admin.site.register(Band)  # Use the default options
admin.site.register(Member, MemberAdmin)  # Use the customized options

Internationalization

Django offers full support for translating text into different languages, plus locale-specific formatting of dates, times, numbers, and time zones. It lets developers and template authors specify which parts of their apps should be translated or formatted for local languages and cultures, and it uses these hooks to localize Web applications for particular users according to their preferences.

from django.shortcuts import render
from django.utils.translation import gettext

def homepage(request):
    """
    Shows the homepage with a welcome message that is translated in the
    user's language.
    """
    message = gettext('Welcome to our site!')
    return render(request, 'homepage.html', {'message': message})

How Django Works Behind the Scenes

Django is a Python-based web framework used by millions of developers and billions of consumers through popular apps like Instagram. It is open source, meaning the code is available for free on Github and can be downloaded onto any developer’s computer and used alongside the official documentation.

Django’s code is open source and available to all. Django’s organization is managed by a non-profit, the DSF, with a miniscule budget. And Django code is lead by a core team of volunteers, two paid Django Fellows, and a larger group of contributors.

One of the best ways to become more involved in Django is to attend an annual conference and meet all the contributors in person. Currently there are DjangoCons in the US, Europe, Australia, and Africa in 2020 for the first time. I hope to see some of you there!