Django — The Web framework for perfectionists with deadlines

The Web framework for perfectionists with deadlines

The " " is silent.

The Web framework for perfectionists with deadlines

frame·work n. 1. A structure for supporting or enclosing something
else. 2. A set of assumptions, concepts, values, and practices that constitutes a way of viewing reality. The American Heritage® Dictionary of the English Language, Fourth Edition copyright ©2000 by Houghton Mifflin Company.

frame·work n. 1. A structure for supporting or enclosing something
else. 2. A set of conventions that constitutes a way of doing something. The American Heritage® Dictionary of the English Language, Fourth Edition copyright ©2000 by Houghton Mifflin Company.

provides a structure and a set of conventions for developing
web applications.

In the beginning...

#!/usr/bin/perl print "Content-‐type: text/html\n\n"; print <<HTML; <html> <body>
<h1>Hello!</h1> </body> </html> HTML exit;

You're on your own. http://ra3ndy.deviantart.com/art/Sad-Panda-69204875

framework

structure + convention convenience elegance security framework

Tagxedo (http://www.tagxedo.com)

Model Template View persistence presentation personality

Model Template View data

Model Template View data presentation

Model Template View data presentation control

Models are Python classes with state and behavior

from django.db import models class Band(models.Model): name
= models.CharField(max_length=100) year_formed = models.IntegerField() def make_musical_awesome(self): # TODO: discover secret to success

name = models.CharField(max_length=100) year_formed
= models.IntegerField() from django.db import models class Band(models.Model): name = models.CharField(max_length=100) year_formed = models.IntegerField() def make_musical_awesome(self): # TODO: discover secret to success state

def make_musical_awesome(self):
# TODO: discover secret to success from django.db import models class Band(models.Model): name = models.CharField(max_length=100) year_formed = models.IntegerField() def make_musical_awesome(self): # TODO: discover secret to success behavior

mysql> DESCRIBE music_band; +-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐+ | Field
| Type | Null | Key | Default | Extra | +-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | char(100) | NO | | | | | year_formed | int(11) | NO | | | | +-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐-‐-‐-‐+-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐+

field types AutoField BigIntegerField BinaryField BooleanField CharField DateField DateTimeField DecimalField
EmailField FileField FilePathField FloatField ImageField IntegerField IPAddressField NullBooleanField PositiveIntegerField SlugField SmallIntegerField TextField TimeField URLField ForeignKey ManyToManyField OneToOneField

Model instances can be created, read, updated, and destroyed. CRUD

Band.objects.create( name="The Detours", year_formed=1961)
Create

band = Band.objects.get(name="The Detours") print band.name The Detours print band.year_formed
1961 Read

band.name = "The Who" band.year_formed = 1964 band.save() Update

band.delete() Delete

INSERT INTO music_band VALUES ... SELECT * FROM music_band WHERE
... UPDATE music_band SET ... DELETE FROM music_band WHERE ...

Find just the instances you're looking for...

Band.objects.create( name="RUSH", year_formed=1968) Band.objects.create(
name="Led Zeppelin", year_formed=1968) Band.objects.create( name="The Police", year_formed=1977)

bands = Band.objects.filter(year_formed=1968) for band in bands:
print band.name RUSH Led Zeppelin

relationships

from django.db import models class Band(models.Model): name
= models.CharField(max_length=100) year_formed = models.IntegerField() members = models.ManyToManyField("Musician") class Musician(models.Model): name = models.CharField(max_length=100)

band.members.create(name="Pete Townshend") band.members.create(name="John Entwistle") band.members.create(name="Roger Daltrey") band.members.create(name="Doug Sandom")

doug = Musician.objects.get(name="Doug Sandom") band.members.remove(doug) keith = Musician.objects.create(name="Keith Moon") band.members.add(keith)
band.members.clear()

managers & querysets

Band.objects.filter(year_formed=1968) Model – instances become database rows Manager – methods
for managing model instances returns a QuerySet

bands = Band.objects.filter(year_formed=1968) QuerySet

bands = Band.objects.filter(year_formed=1968) Iterate for band in bands:
print band.name

bands = Band.objects.filter(year_formed=1968)\
.exclude(name="RUSH")\ .order_by("name") Chain

chainable methods filter exclude annotate order_by reverse distinct values values_list
dates datetimes none all select_related prefetch_related extra defer only using select_for_update

terminal methods get create get_or_create bulk_create count in_bulk iterator latest
earliest aggregate exists update delete

if Band.objects.filter(year_formed=1968)\
.exclude(name="RUSH")\ .exists(): # do something num = Band.objects.filter(year_formed=1968)\ .exclude(name="RUSH")\ .count() print num

field lookups

Band.objects.filter(year_formed=1968) field lookups {

Band.objects.filter(year_formed=1968,
name="RUSH") field lookups {

__ mifflin __

__ mifflin __ DUNDER

Band.objects.filter(name__startswith="R") DUNDER Band.objects.filter( year_formed__range=[1960,1970])

field lookups exact iexact contains icontains in gt gte lt
lte startswith istartswith endswith iendswith range year month day week_day hour minute second isnull search regex iregex

span relationships

class Band(models.Model): name = models.CharField(max_length=100)
year_formed = models.IntegerField() members = models.ManyToManyField("Musician") class Musician(models.Model): name = models.CharField(max_length=100) Band.objects.filter(members__name="Keith Moon")

mustache mustache {{ }}

<html> <body> <p>{{ band.name }} rocks!</p>
</body> </html>

<html> <body> <ul>
{% for band in bands %} <li> {{ band.name }} has been rocking since {{ band.year_formed }}. </li> {% endfor %} </ul> </body> </html>

{% for %} loops {% if %} conditionals {% include
%} fragments Template Tags

{{ name|title }} {{ names|pluralize }} {{ name|truncatechars:9 }} Template
FILTERS

Django's template language is intentionally simple.

TAG Business logic doesn't belong in templates.

If you need more power, write your own tags...

Views are functions that take a request and return a
response.

def hello(request): return HttpResponse('Hello!')

def hello(request): return HttpResponse('Hello!') request

response def hello(request): return HttpResponse('Hello!')

What's in a Request?

URL path request.path /say/hello HTTP method request.method GET Query string
request.GET foo=bar&blee=baz Form data request.POST <form method="POST"> Cookies request.COOKIES key=value HTTP headers request.META Content-type: text/html Logged-in user request.user.name Keyser Söze

What's in a RESPONSE?

Content response.content Hello! Status code response.status_code 200 HTTP headers response['Content-Type']
text/html Cookies response.set_cookie('foo', 'bar')

shortcuts

from django.shortcuts import render_to_response def hello(request): context
= { "name": "Pete", } template = "hello.html" return render_to_response(template, context)

from django.shortcuts import get_object_or_404 from django.shortcuts import render_to_response def hello(request):
band = get_object_or_404(Band, name="RUSH") context = { "band": band, } template = "hello.html" return render_to_response(template, context)

Your app needs a roadmap

from django.conf.urls import patterns from views import hello urlpatterns =
patterns( ("hello", hello), )

def hello(request): return HttpResponse('Hello!') http://example.com/hello

from django.conf.urls import patterns from views import hello urlpatterns =
patterns( ("hello/(.+)", hello), ) regex

def hello(request, name): band = get_object_or_404(Band, name=name)
... http://example.com/hello/The+Who

but that's not all... forms middleware context processors signals migrations
admin site authentication messages redirects site maps sessions static assets

Why ? Python

Why ? Python Philosophy

Why ? Python Philosophy Ecosystem

Tagxedo (http://www.tagxedo.com)

n @claymcclure / daemons.net

Django — The Web framework for perfectionists w...

Django — The Web framework for perfectionists with deadlines

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