Django for Beginners

An Introduction

Jason Davies

PyCon UK 2007

Django Reinhardt

ljworld.com

www.djangoproject.com

Overview of this Tutorial

Brief introduction and philosophy

Creating Django models

The automatic admin interface

Views (and URLs)

Templates

Comparison with other frameworks

Django's Mission Statement

“Django is a high-level Python web framework that encourages rapid development and clean, pragmatic design.”

Django Requirements

Python (2.3+)

PostgreSQL / MySQL / SQLite / ...

Apache + mod_python / FastCGI / ...

“Projects” $ django-admin.py startproject myproject

myproject/ __init__.py manage.py settings.py urls.py

$ ./manage.py runserver Validating models... 0 errors found. Django version 0.96-pre, using settings 'myproject.settings' Development server is running at http://127.0.0.1:8000/ Quit the server with CONTROL-C.

“Apps” $ django-admin.py startapp blog

myproject/ blog/ __init__.py models.py views.py __init__.py manage.py settings.py urls.py

Creating Models from django.db import models class Blog(models.Model): title = models.CharField(maxlength=200) class Post(models.Model): title = models.CharField(maxlength=200) body = models.TextField() blog = models.ForeignKey(Blog) pub_date = models.DateTimeField()

Activating Models $ ./manage.py syncdb Creating table blog_blog Creating table blog_post Loading 'initial_data' fixtures... No fixtures found.

Activating the Admin Interface from django.db import models class Blog(models.Model): title = models.CharField(maxlength=200) class Admin: list_display = ['title'] class Post(models.Model): title = models.CharField(maxlength=200) body = models.TextField() blog = models.ForeignKey(Blog) pub_date = models.DateTimeField() class Admin: list_display = ['title', 'pub_date']

Model API $ ./manage.py shell >>> from myproject.blog import Blog >>> b = Blog( ... title=”Jason's Fantastic Blog!!!”) >>> b.save()

>>> all_blogs = Blog.objects.all() >>> print all_blogs [<Blog: Blog object>] >>> print all_blogs.name Jason's Fantastic Blog!!! >>> b = Blog.objects.get(name__contains='Jason') >>> print b.title Jason's Fantastic Blog!!!

URLs ROOT_URLCONF = 'myproject.urls'

URLconfs from django.conf.urls.defaults import * from myproject.blog.views import * urlpatterns = patterns('', (r'^admin/', include('django.contrib.admin.urls')), (r'^blog/$', post_list), (r'^blog/(?P<id>d+)/$', post_list), )

Views from django.http import HttpResponse def post_list(request): return HttpReponse(“This is a list of posts!”)

from django.http import HttpResponse from myproject.blog.models import Post def post_list(request): r = “<ul>” posts = Post.objects.order_by(“-pub_date”) for post in posts: r += “<li>%s: %s</li>” % (post.title, post.body) r += “</ul>” return HttpResponse(r) More realistic...

from django.shorcuts import render_to_response from myproject.blog.models import Post def post_list(request): posts = Post.objects.order_by(“-pub_date”) return render_to_response('blog/post_list.html', { 'post_list': posts, }) Better!

from django.shorcuts import render_to_response from myproject.blog.models import Post def post_detail(request, id): post = get_object_or_404(Post, id=id) return render_to_response('blog/post_detail.html', { 'post': post, }) For completeness...

Templates <html> <body> <h1>Jason's Fantastic Blog!!!</h1> <ul> {% for p in post_list %} <li> <a href=”{{ p.id }}/”>{{ p.title|escape }}</a> </li> {% endfor %} </ul> </body> </html>

The magic dot

p[“name”]

p.name

p.name()

Filters {{ var|escape|linebreaks|... }}

base.html <html> <head> <title>{% block title %}{% endblock %} </head> <body> <div id=”content”> {% block content %}{% endblock %} </div> <div id=”footer”> {% block footer %} Copyright Jason Davies 2007. {% endblock %} </div> </body> </html>

{% extends “base.html” %} {% block title %} Posts | {{ block.super }} {% endblock %} {% block content %} <h1>Blog Posts ({{ post_list|length }} total)</h1> <ul> {% for post in post_list %} <li> <a href=”{{ post.id }}/”> {{ post.title|escape }} </a> </li> {% endfor %} </ul> {% endblock %}

Ruby on Rails http://www.rubyonrails.org/

http://www.alrond.com/en/2007/jan/25/performance-test-of-6-leading-frameworks/

Thank you for listening. Jason Davies [email_address] http://www.jasondavies.com/

http://www.mercurytide.co.uk/whitepapers/django-cheat-sheet/