Django è uno dei framework web più apprezzati e utilizzati dalla comunità Python (e non solo). I suoi punti di forza sono rappresentati dal suo utilizzo rapido e intuitivo, l'ottima documentazione e una larga comunità di sviluppatori ed utilizzatori. A più di un anno di distanza dal rilascio della versione 0.96 le feature e i miglioramenti introdotti sono stati molti. La presentazione mostra alcune di queste novità e l'utilizzo avanzato di alcuni componenti del framework.

1. Django Utilizzo avanzato e nuove funzionalità

36. Form preview # pycon2.contacts.preview import pprint from django.http import HttpResponse from django.contrib.formtools.preview import FormPreview from pycon2.contacts.forms import ContactForm class ContactFormPreview(FormPreview): def done(self, request, cleaned_data): # do something with cleaned_data... output = pprint.pformat(cleaned_data)‏ return HttpResponse(output, mimetype='text/plain')‏ contact = ContactFormPreview(ContactForm)‏

39. Form wizard # pycon2.contacts.forms from django import newforms as forms from django.http import HttpResponseRedirect from django.contrib.formtools.wizard import FormWizard from django.core.urlresolvers import reverse class PollOne(forms.Form): name = forms.CharField()‏ email = forms.EmailField() job_position = forms.CharField()‏ LANGUAGE_CHOICES = ( ('python', 'Python'), ('ruby', 'Ruby'), ('perl', 'Perl'), ('php', 'PHP'), ) class PollTwo(forms.Form): languages = forms.MultipleChoiceField(choices=LANGUAGE_CHOICES)‏ preferred_language = forms.ChoiceField(choices=LANGUAGE_CHOICES)‏

40. Form wizard # pycon2.contacts.forms class PollWizard(FormWizard): def done(self, request, form_list): form_data = [form.cleaned_data for form in form_list] # do something with form_data return HttpResponseRedirect(reverse('poll_done')) def get_template(self, step): '''Override default template “forms/wizard.html”''' return ['contacts/poll_%s.html' % step, 'contacts/poll.html'] # pycon2.contacts.urls from django.conf.urls.defaults import * from pycon2.contacts.forms import PollOne, PollTwo, PollWizard urlpatterns = patterns('', url(r'^poll/$', PollWizard([PollOne, PollTwo]), name='poll'), url(r'^poll/done/$', 'django.views.generic.simple.direct_to_template', {'template': 'contacts/poll_done.html'}, name='poll_done') )‏

41. Form wizard {# templates/contacts/poll.html #} {% extends 'base_site.html' %} {% block title %} Poll - step {{ step }} of {{ step_count }} {% endblock %} {% block content %} <form action='.' method='POST'> <input type=&quot;hidden&quot; name=&quot;{{ step_field }}&quot; value=&quot;{{ step0 }}&quot; /> {{ form.as_p }} {{ previous_fields|safe }} <p> <input type=&quot;submit&quot; value=&quot;Submit&quot; /> </p> </form> {% endblock %}

45. ModelForm: esempio di utilizzo # pycon2.places.views @login_required def place_add(request, template='places/place_add.html'): if request.method == 'POST': form = PlaceForm(request.POST)‏ if form.is_valid(): place = form.save(commit=False)‏ place.author = request.user place.save()‏ return HttpResponseRedirect(place.get_absolute_url())‏ else: form = PlaceForm()‏ return render_to_response(template, {'form': form}, context_instance=RequestContext(request))‏

46. ModelForm: esempio di utilizzo # pycon2.places.views @login_required def place_edit(request, place_id, template='places/place_edit.html'): place = get_object_or_404(Place, pk=place_id)‏ if request.method == 'POST': form = PlaceForm(request.POST, instance=place)‏ if form.is_valid(): form.save()‏ return HttpResponseRedirect(place.get_absolute_url())‏ else: form = PlaceForm(instance=place)‏ return render_to_response(template, {'form': form, 'place': place}, context_instance=RequestContext(request))‏

49. newforms-admin: esempio di utilizzo # pycon2.places.models from django.contrib import admin class Place(models.Model): name = models.CharField(max_length=100) description = models.TextField(blank=True) created = models.DateField(default=datetime.now) location = models.ForeignKey(Location)‏ author = models.ForeignKey(User)‏ class Location(models.Model): name = models.CharField(max_length=100)‏ latitude = models.DecimalField(max_digits=8, decimal_places=6)‏ longitude = models.DecimalField(max_digits=8, decimal_places=6) # register models into admin site admin.site.register(Place) admin.site.register(Location)‏

50. newforms-admin: esempio di utilizzo class PlaceOptions(admin.ModelAdmin): list_display = ('name', 'location', 'author') search_fields = ('name', 'description') def has_change_permission(self, request, obj=None): if obj: if request.user != obj.author: return False return super(PlaceOptions, self).has_change_permission(request, obj) class PlaceInline(admin.TabularInline)‏ model = Place extra = 5 class LocationOptions(admin.ModelAdmin): inlines = [PlaceInline] # register models into admin site admin.site.register(Place, PlaceOptions) admin.site.register(Location, LocationOptions)‏

60. Signals: utilizzo d'esempio # pycon2.members.models from django.db import models from django.contrib.auth.models import User from django.dispatch import dispatcher from django.db.models import signals class Profile(models.Model): user = models.ForeignKey(User)‏ photo = models.ImageField(upload_to='pics', blank=True)‏ bio = models.TextField(blank=True)‏ def create_profile(sender, instance, signal, *args, **kwargs): if kwargs.get('created'): try: instance.get_profile()‏ except Profile.DoesNotExist: profile = Profile(user=instance)‏ profile.save()‏ dispatcher.connect(create_profile, signal=signals.post_save, sender=User)‏