Django introduction

Introduction to Django Master in Free Software 2009/2010 Joaquim Rocha <jrocha@igalia.com> 3, July 2010

What is it? "Django is a highlevel Python Web framework that encourages rapid development and clean, pragmatic design." From Django official website Master in Free Software | 20092010 2

What is it? Internal project of Lawrence JournalWorld in 2003 Should help journalists meet fast deadlines Should not stand in the journalists' way Got its name after the famous guitarrist Django Reinhardt Master in Free Software | 20092010 3

The framework ObjectRelational Mapper Automatic Admin Interface Elegant URL Design Powerful Template System i18n it's amazing...! Master in Free Software | 20092010 4

Big community Django has a big community and an extensive list of Django apps Search for them in http://code.google.com Other interesting websites: * Django sites: http://www.djangosites.org * Django people: http://www.djangopeople.com Master in Free Software | 20092010 5

Deployment FastCGI mod_python mod_wsgi ... Master in Free Software | 20092010 6

DB Backend Officially supported: PostgreSQL MySQL SQLite Oracle Master in Free Software | 20092010 7

Using Django Master in Free Software | 20092010 8

Installation Just get a tarball release or checkout the sources: http://djangoproject.com/download Then: # python setup.py install Or: # easy_install django Master in Free Software | 20092010 9

Development Master in Free Software | 20092010 10

Creating a project $ djangoadmin.py startproject Project Project __init__.py manage.py settings.py urls.py Master in Free Software | 20092010 11

Running the project $ ./manage.py runserver ...and open your browse at localhost:8000 Master in Free Software | 20092010 12

Running the project Master in Free Software | 20092010 13

Development Django Projects have Apps Apps are the projects' components Master in Free Software | 20092010 14

Creating an App $ ./manage.py startapp my_app my_app __init__.py models.py tests.py views.py Master in Free Software | 20092010 15

Building the database $ ./manage.py syncdb Master in Free Software | 20092010 16

Project's configuration Easy configuration in the settings.py file Master in Free Software | 20092010 17

Building the database $ ./manage.py syncdb Master in Free Software | 20092010 18

Development Django follows the MTV design pattern: ModelTemplateView Master in Free Software | 20092010 19

Models Models are a series of classes describing objects They represent the database objects Never touch SQL again! Master in Free Software | 20092010 20

Models class Post(models.Model): title = models.CharField(max_length = 500) content = models.TextField() date = models.DateTimeField(auto_now = True) ... Master in Free Software | 20092010 21

Views Views are a series of functions that normally process some models and render HTML It's where the magic happens! How to get all blog posts from the latest 5 days and order them by descending date? Master in Free Software | 20092010 22

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}) Master in Free Software | 20092010 23

Templates Will not let you repeat yourself! Will save designers from the code. Master in Free Software | 20092010 24

Templates <html> <head> <title>{% block title %}{% endblock %}</title> </head> <body> {% block content %}{% endblock %} </body> </html> Master in Free Software | 20092010 25

Templates {% 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 %} Master in Free Software | 20092010 26

URLs In Django, the URLs are part of the design! urls.py use regular expressions to match URLs with Views Master in Free Software | 20092010 27

URLs urlpatterns = patterns('Project.some_app.views', (r'^$', 'index'), (r'^posts/(?P<r_id>d+)/$', 'view_latest_posts'), (r'^create/$', 'create'), url(r'^view/post/(?P<p_id>d+)/$', 'view', name = 'view_post'), ) Master in Free Software | 20092010 28

Forms Series of classes that represent an HTML form Will let you easily configure the expected type of the inputs, error messages, labels, etc... Master in Free Software | 20092010 29

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) Master in Free Software | 20092010 30

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, }) Master in Free Software | 20092010 31

Forms The quick way: <form action="/create/" method="POST"> {{ form.as_p }} <input type="submit" value="Create" /> </form> Master in Free Software | 20092010 32

Where to go from here? Master in Free Software | 20092010 33

Django hosts An extensive list is can be found at: http://code.djangoproject.com/wiki/DjangoFriendlyWe bHosts Popular ones: http://www.statopia.com/corporate/blog/2007/aug/05/ PopularDjangoHostingService/ Google's AppEngine is also Django friendly: http://appengine.google.com/ Master in Free Software | 20092010 34

Help Django Docs http://docs.djangoproject.com Some books ● Learning Website Development with Django, Packt ● Practical Django Projects, Apress ● Pro Django, Apress Master in Free Software | 20092010 35

Django introduction

by Joaquim Rocha

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