Django Intro

Introduction to Django
Master en Software Libre Caixanova

May 22nd 2009

whoami

● Portuguese since 1985
● GTK+ developer
● Proud Pythonista
● Djangonaut since 2007
● Igalian since 2008
And if you insist... http://www.joaquimrocha.com

MSWL Caixanova · Vigo · May 22nd 2009 | Joaquim Rocha | jrocha@igalia.com

My Latest Django Project

Rancho
http://www.getrancho.com


What's Django


What's Django?

quot;Django is a high-level Python Web framework
that encourages rapid development and clean,
pragmatic design.quot;
From Django official website


Young But Strong

● Internal project of Lawrence Journal-World in
2003
● Should help journalists meet fast deadlines
● Should not stand in the journalists' way
● Got its name after the famous guitarrist Django
Reinhardt


The Framework

● Object-Relational Mapper
● Automatic Admin Interface
● Elegant URL Design
● Powerful Template System
● i18n
it's amazing...!


MTV

Model-Template-View

● Model: What things are
● Templates: How things are presented
● Views: How things are processed


Deployment

● FastCGI
● mod_python
● mod_wsgi
● ...


DB Backend

● PostgreSQL
● MySQL
● SQLite
● Oracle


Big Community

● Django People:
– http://djangopeople.net
● Django Pluggables:
– http://djangopluggables.com
● Django Sites:
– http://www.djangosites.org
● ...


Using Django


Installation

Just get a tarball release or checkout the sources:
http://www.djangoproject.com/download/

Then:
# python setup.py install

... yeah, that it!


Development

Django Projects have applications


Project

$ django-admin.py startproject Project

Project/
__init__.py
manage.py
settings.py
urls.py


Project

Does it work?

$ ./manage.py runserver


Project


Applications

Apps are the project's components

$ ./manage.py startapp recipe

recipe/
__init__.py
models.py
tests.py
views.py


Configuration

settings.py
Easy configuration


Building The Database

$ ./manage.py syncdb


Models

models.py, series of classes describing objects

Represent the database objects.
Never touch SQL again!


Models

class Post(models.Model):
title = models.CharField(max_length = 500)
content = models.TextField()
date = models.DateTimeField(auto_now = True)
...


Views

views.py, series of functions that will normally process some models and render HTML

Where the magic happen!

How to get all blog posts from the latest 5 days and order them by
descending date?


Views

import datetime

def view_latest_posts(request):
# Last 5 days
date = datetime.datetime.now() -
datetime.timedelta(5)
posts = Post.objects.filter(date__gte =
date).order_by('-date')

return render_to_response('posts/show_posts.html',
{'posts': posts})


Template

Will let you not repeat yourself!

Will save designers from the code.


Template

<html>
<head>
<title>{% block title %}{% endblock %}</title>
</head>
<body>
{% block content %}{% endblock %}
</body>
</html>


Template

{% extends quot;base.htmlquot; %}

{% block title %}Homepage{% endblock %}

{% block content %}
<h3>This will be some main content</h3>

{% for post in posts %}
<h4>{{ post.title }} on {{ post.date|date:quot;B d, Yquot;|upper }}<h4>

<p>{{ post.content }}</p>
{% endfor %}

{% url project.some_app.views.some_view some arguments %}

{% endblock %}


URLs

In Django, URLs are part of the
design!


URLs

urls.py use regular expressions to match URLs with views

urlpatterns = patterns('Project.some_app.views',
(r'^$', 'index'),

(r'^posts/(?P<r_id>d+)/$', 'view_latest_posts'),

(r'^create/$', 'create'),
)


Forms

forms.py, series of classes that represent an HTML form

Will let you easily configure the expected type of the
inputs, error messages, labels, etc...


Forms

class CreatePost(forms.Form):
title = forms.CharField(label = quot;Post Titlequot;,
max_length = 500,
widget = forms.TextInput(attrs={
'class': 'big_entry'
}))
content = forms.CharField()
tags = forms.CharField(required = False)


Forms

def create_post(request):
if request.method == 'POST':
form = CreatePost(request.POST)
if form.is_valid():
# Create a new post object with data
# from form.cleaned_data
return HttpResponseRedirect('/index/')
else:
form = CreatePost()

return render_to_response('create.html', {
'form': form,
})


Forms

The quick way...

<form action=quot;/create/quot; method=quot;POSTquot;>
{{ form.as_p }}
<input type=quot;submitquot; value=quot;Createquot; />
</form>


Performance


Performance

For those who doubt...

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


HELP!


HELP!

Django Docs

http://docs.djangoproject.com

Some books

● Learning Website Development with Django,
Packt
● Practical Django Projects, Apress
● Pro Django, Apress

End

Thank you!
Questions?


Django Intro

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