An introduction to programming with Django, and what makes it useful in today's world of web development.

1. Unchain Your Web
Development with Django
The web framework for perfectionists with deadlines.

2. Who am I?
● Started using Python 1.5.2 in 1998
● Started using Django 0.96 in 2008
● Contributing to open source projects since ~2000
● @mrbeersnob
● github.com/tarkatronic

3. What is Django?

4. No, really, what is it?
The web framework for professionals with deadlines
● Originally built for the Lawrence Journal-World newspaper in 2003
● A bundled collection of tools to build powerful web applications quickly
● Focused on automation and DRY

5. Who actually uses this thing?
● Disqus
● Instagram
● Pinterest
● Washington Post
● National Geographic
● Many, many more…
● https://www.djangosites.org/

6. Why should I use it?
● ORM
● Caching
● Internationalization
● Class-based views!
● Templating
● Automatically generated admin interface
● Database migrations
● Built-in management commands

7. Django doesn’t provide ____. Do I have to build it?
● Social authentication? django-allauth
● REST API? django-rest-framework
● Two factor authentication? django-two-factor-auth
● CMS? wagtail, django-cms, etc
● https://www.djangopackages.com/
● https://djangosnippets.org/

8. Let’s get started!

9. Setting things up
● pip install Django
● django-admin.py startproject cocktails
● …
● Profit!

10. Okay, maybe a little more than that.
./manage.py runserver
…
Starting development server at http://127.0.0.1:8000/

11. Creating an application
django-admin.py startapp recipes
recipes/
migrations/
__init__.py
__init__.py
admin.py
models.py
tests.py
views.py
settings.py:
INSTALLED_APPS = (
…
'cocktails.recipes'
)

12. First step: Models
from django.db import models
class Ingredient(models.Model):
OUNCE = 'ounce'
TEASPOON = 'tsp'
TABLESPOON = 'tbsp'
DASH = 'dash'
MEASUREMENTS = (
(OUNCE, 'Ounce(s)'),
(TEASPOON, 'Teaspoon(s)'),
(TABLESPOON, 'Tablespoon(s)'),
(DASH, 'Dash(es)'),
)
name = models.CharField(max_length=255)
measurement = models.CharField(max_length=5, choices=MEASUREMENTS, null=True, blank=True)
def __str__(self):
return self.name

13. A couple more...
class Drink(models.Model):
name = models.CharField(max_length=255)
components = models.ManyToManyField('Ingredient', through='Component', related_name='drinks')
def __str__(self):
return self.name
class Component(models.Model):
drink = models.ForeignKey('recipes.Drink', related_name='+')
ingredient = models.ForeignKey('recipes.Ingredient', related_name='+')
amount = models.FloatField()
def __str__(self):
return '%s %s %s (%s)' % (self.ingredient.name, self.amount,
self.ingredient.get_measurement_display() or '', self.drink.name)

14. One more piece
class Step(models.Model):
drink = models.ForeignKey('Drink', related_name='steps')
text = models.TextField()
class Meta:
order_with_respect_to = 'drink'
def __str__(self):
return '%s step #%s' % (self.drink.name, self._order + 1)

15. Time to set up the database...
CREATE DATABASE;
CREATE TABLE …;
...right?

16. Nope! Migrations to the rescue.
./manage.py makemigrations
Migrations for 'recipes':
0001_initial.py:
- Create model Component
- Create model Drink
- Create model Ingredient
- Create model Step
- Add field components to drink
- Add field drink to component
- Add field ingredient to component
- Set order_with_respect_to on step to drink
./manage.py migrate
Operations to perform:
Synchronize unmigrated apps: staticfiles, messages
Apply all migrations: admin, contenttypes, recipes, auth, sessions
… lots more words …
Done!

17. About that admin interface...
admin.py:
from django.contrib import admin
from .models import Component, Drink, Ingredient, Step
class ComponentInline(admin.TabularInline):
model = Component
class StepInline(admin.StackedInline):
model = Step
class DrinkAdmin(admin.ModelAdmin):
inlines = [ComponentInline, StepInline]
admin.site.register(Component)
admin.site.register(Drink)
admin.site.register(Ingredient)
admin.site.register(Step)

18. Creating an admin user
Another built-in management command!
./manage.py createsuperuser
Username (leave blank to use 'jwilhelm'):
Email address: jwilhelm@opay.io
Password:
Password (again):
Superuser created successfully.

19. Log in, and like magic, we get...

20. Adding some records

21. Our inlines at work

22. Making things visible: views
views.py:
from django.core.urlresolvers import reverse_lazy
from django.views.generic import DetailView, ListView
from .models import Component, Drink
class DrinkListView(ListView):
model = Drink
class DrinkDetailView(DetailView):
model = Drink
def get_context_data(self, **kwargs):
context = super(DrinkDetailView, self).get_context_data(**kwargs)
context.update({'components': Component.objects.filter(drink=self.get_object())})
return context

23. Pulling it together with a couple templates
base.html:
<html>
<head>
<title>Cocktail Database</title>
</head>
<body>
{% block content %}{% endblock %}
</body>
</html>

24. List all the things!
recipes/drink_list.html:
{% extends "base.html" %}
{% block content %}
{% for drink in object_list %}
{% if forloop.first %}
<ul>
{% endif %}
<li><a href="{% url 'drink_detail' drink.id %}">{{ drink.name }}</a></li>
{% if forloop.last %}
</ul>
{% endif %}
{% empty %}
No drinks yet in the database.
{% endfor %}
{% endblock %}

25. It's all in the details
recipes/drink_detail.html:
{% extends "base.html" %}
{% block content %}
<h1>{{ drink.name }}</h1>
<dl>
<dt>Ingredients</dt>
<dd>
<ul>
{% for component in components %}
<li>{{ component.amount }}{% if component.ingredient.measurement %} {{
component.ingredient.measurement }}{% endif %} {{ component.ingredient.name }}</li>
{% endfor %}
</ul>
</dd>
...

26. Details, continued
...
<td>Steps</td>
<dd>
<ol>
{% for step in drink.steps.all %}
<li>{{ step.text }}</li>
{% endfor %}
</ol>
</dd>
</dl>
{% endblock %}

27. Just one more piece: urls
urls.py:
from cocktails.recipes.views import DrinkDetailView, DrinkListView
urlpatterns = [
...
url(r'^drinks/$', DrinkListView.as_view(), name='drink_list'),
url(r'^drinks/(?P<pk>[0-9]+)/$', DrinkDetailView.as_view(), name='drink_detail'),
]

28. The (ugly, ugly) fruits of our labor

29. The (slightly less ugly) details

30. The full code, plus a bit more
django-cocktails repository: https://github.com/tarkatronic/django-cocktails

31. What if I need help?
“I came for the auto generated admin, but I stayed for the community.”
-Ola Sitarska
● StackOverflow - http://stackoverflow.com/questions/tagged/django
● django-users mailing list - https://groups.google.com/forum/#!forum/django-
users
● IRC: #django on Freenode (I'm often on as TheJoey)

32. Now, go learn more!
Django Project website: http://www.djangoproject.com/
Django Girls tutorial: http://tutorial.djangogirls.org/
Getting Started with Django: http://gettingstartedwithdjango.com/
Two Scoops of Django: http://twoscoopspress.org/

33. Cheers!