Class Based Views

Links

Note: The following links are useful, and helpful, but best to look in the actual source code:

Diagram

../misc/class-based-views.pdf

Learning

CreateView and UpdateView both have the form_valid method which can be used to add extra data to the form instance data before it is saved. As a general principle, I think we should only use form_valid when the data we want to add is available in the view, but not in the form e.g. self.request.user.

If the data is available in the form, then we should override the form save method.

Reinout van Rees
- Using Django’s class based views
- Django class based view walkthrough: TemplateView

Request

The request object is available as self.request e.g. self.request.user. Note: For this to work you will probably need the django.core.context_processors.request context processor.

Sample

JSON

import decimal
import simplejson
from django.http import HttpResponse
from django.utils.cache import add_never_cache_headers

class DecimalEncoder(simplejson.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, decimal.Decimal):
            return str(obj)
        return super(DecimalEncoder, self).default(obj)

def dumps(*args, **kwargs):
    return simplejson.dumps(
        *args,
        sort_keys=True,
        separators=(',', ': '),
        indent=4,
        use_decimal=False,
        cls=DecimalEncoder,
        **kwargs
    )

def loads(*args, **kwargs):
    return simplejson.loads(*args, **kwargs)

class JsonResponse(HttpResponse):
    def __init__(self, request, content, **kwargs):
        data = dumps(content)
        try:
            if "application/json" in request.META['HTTP_ACCEPT_ENCODING']:
                mimetype = 'application/json'
            else:
                raise KeyError('application/json not accepted')
        except:
            mimetype = 'text/plain'
        super(JsonResponse, self).__init__(data, mimetype, **kwargs)
        add_never_cache_headers(self)

from django.views.generic import View
from somewhere.above import JsonResponse
from django.views.decorators.csrf import csrf_exempt
from django.utils.decorators import method_decorator

class MyView(View):
    @method_decorator(csrf_exempt)
    def dispatch(self, *args, **kwargs):
        return super(MyView, self).dispatch(*args, **kwargs)

    def get(self, request):
        return JsonResponse(request, { 'foo': 'bar'})

    def post(self, request):
        data = request.POST
        print data
        return JsonResponse(request, {
            'response': data
        })

List

From passing parameters to filter of view, you can override the views get_queryset method:

from django.views.generic.list import ListView

class MyList(ListView):
    def get_queryset(self):
        return Village.objects.filter(county__in='Devon')

Template

from django.views.generic.base import TemplateView

class SomeView(TemplateView):
    template_name = 'my_app/someview.html'

    def get_context_data(self, **kwargs):
        return {'name': 'pat'}

import ...

urlpatterns = patterns(
    url(regex=r'^class_based_view/$',
        view=my_app.views.SomeView.as_view(),
        name='my_view'),

urlpatterns = patterns('',
    url(regex=r'^$',
        view=TemplateView.as_view(template_name='home.html'),
        name='app.home'
    ),

Security

Basic login_required security can be set-up in urls.py:

from django.contrib.auth.decorators import login_required

url(regex=r'^private/$',
    view=login_required(TemplateView.as_view(template_name='private.html')),
    name='private'
),