django intro

Introduction to Django

Master en Software Libre Caixanova

May 22nd 2009

MSWL Caixanova · Vigo · May 22nd 2009 | Joaquim Rocha | [email protected]

whoami

● Portuguese since 1985● GTK+ developer● Proud Pythonista● Djangonaut since 2007● Igalian since 2008

And if you insist... http://www.joaquimrocha.com

http://www.joaquimrocha.com/


My Latest Django Project

Ranchohttp://www.getrancho.com

http://www.getrancho.com/


What's Django


What's Django?

"Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design."

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

● ...

http://djangopeople.net/

http://djangopluggables.com/

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 "base.html" %}

{% 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:"B d, Y"|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 = "Post Title",

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="/create/" method="POST"> {{ form.as_p }} <input type="submit" value="Create" /></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

http://docs.djangoproject.com/


End

Thank you!

Questions?

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