Post on 06-May-2015
description
The Django Web Framework
Simon Willisonhttp://simonwillison.net/
EuroPython, 3rd July 2006
Web development on Journalism deadlines
... in three days
CharacteristicsClean URLs
Loosely coupled components
Designer-friendly templates
Less code
Really fast development
Components
URL dispatching
http://www.example.com/poll/5/
What code shall we execute?
(r'^$', 'views.index'), (r'^hello/$', ‘views.hello'), (r'^poll/(\d+)/$', ‘views.poll'),
Views
def index(request): s = "Hello, World" return HttpResponse(s)
def index(request): name = request.GET['name'] s = "Hi, " + escape(name) return HttpResponse(s)
Models
...(r'^poll/(\d+)/$', 'views.poll'),...
...(r'^poll/(\d+)/$', 'views.poll'),...
def poll(request, poll_id): poll = Poll.objects.get( pk=poll_id ) return HttpResponse( 'Question: ' + poll.question )
class Poll(Model): question = CharField(maxlength=200) pub_date = DateTimeField()
class Choice(Model): poll = ForeignKey(Poll) choice = CharField(maxlength=200) votes = IntegerField()
BEGIN;CREATE TABLE "polls_poll" ( "id" serial NOT NULL PRIMARY KEY, "question" varchar(200) NOT NULL, "pub_date" timestamp with time zone NOT NULL);CREATE TABLE "polls_choice" ( "id" serial NOT NULL PRIMARY KEY, "poll_id" integer NOT NULL REFERENCES "polls_polls" ("id"), "choice" varchar(200) NOT NULL, "votes" integer NOT NULL);COMMIT;
p = Poll( question = "What's up?", pub_date = datetime.now())p.save()
p.choice_set.create( choice = "Some choice", votes = 0)
>>> p.id1
>>> p.question"What's up?"
>>> p.choice_set.all()[<Choice: Some choice>]
>>> Poll.objects.count()7
>>> Poll.objects.filter( pub_date__year = 2006, pub_date__month = 5)["What's up?"]
>>> Poll.objects.all()[0:2]["What's up", "Like Django?"]
Templates
Gluing strings together gets old fast
c = Context({ 'today': datetime.date.today(), 'edibles': ['pear', 'apple', 'orange']})
<h1>Hello World!</h1>
<p>Today is {{ today|date:"jS F, Y" }}</p>
{% if edibles %}<ul> {% for fruit in edibles %} <li>{{ fruit }}</li> {% endfor %}</ul>{% endif %}
<h1>Hello World!</h1>
<p>Today is 2nd July, 2006</p>
<ul> <li>pear</li> <li>apple</li> <li>orange</li></ul>
def hello(request): return render_to_response('hello.html',{ 'today': datetime.date.today(), 'edibles': ['pear', 'apple', 'orange'] })
Common headers and footers?
Template inheritance
base.html<html><head><title> {% block title %}{% endblock %}</title></head><body>{% block main %}{% endblock %}<div id=”footer”>{% block footer %}(c) 2006{% endblock %}</div></body></html>
home.html
{% extends “base.html” %}{% block title %}Homepage{% endblock %}
{% block main %}Main page contents goes here.{% endblock %}
combined<html><head><title> Homepage</title></head><body>Main page contents goes here.<div id=”footer”>(c) 2006</div></body></html>
Loosely coupled
Icing
BengaliCzechWelshDanishGermanGreekEnglishSpanishFrenchGalicianHebrewIcelandicItalian
JapaneseDutch
NorwegianBrazilian
RomanianRussianSlovak
SlovenianSerbianSwedish
UkrainianSimplified ChineseTraditional Chinese
msgid "Usernames cannot contain the '@' character."msgstr "Ім'я не може містити '@' символ"
Forms are boring
1. Display form
2. Validate submitted data
3. If errors, redisplay with:
3.1. Contextual error messages
3.2. Correct fields pre-filled
4. ... do something useful!
Model validation rules + the Manipulator API
do all of this for you
The admin package does even more
No time to talk about...
Generic views
Data object serialisation
Syndication framework
Middleware
Authentication and authorisation
Success stories
170+ public Django-powered sites
http://code.djangoproject.com/wiki/DjangoPoweredSites
90+ contributors
1900+ mailing list subscribers (and 900+ on the development list)
And the Journal-World have convinced three new people to go and work in Kansas
Find out more