Django snippets

"""
==========================
James Crasta's RestfulView
==========================

`As posted on Google Groups`__:

.. __: http://groups.google.com/group/django-developers/msg/5f066b7ce2197e82

-----
Usage
-----

Define a class which extends RestfulView in one of your views::

    class BlogComments(RestfulView):
        def _find_post(self, request, year, month, day, slug):
            " Helper function used in all the comment views "
            try:
                return Post.objects.find_post(year, month, day, slug)
            except Post.DoesNotExist:
                raise Http404()

        def handle_GET(self, request, year, month, day, slug):
            post = self._find_post(year, month, day, slug)
            posts = post.comment_set.filter(previewed=True)
            return render_to_response('blog/comments.html', {'posts': posts}

        def handle_POST(self, request, year, month, day, slug):
            post = self._find_post(year, month, day, slug):
            # do AddManipulator stuff here
            return render_to_response(..... )

Now, either instantiate the class in the view::

    comments = BlogComments() # this line goes after the class definition in your view

...then call that instance in your urlconf::

    urlpatterns = patterns('',
        (r'^archive/(?P<year>\d+)/(?P<month>\d+)/(?P<day>\d+)/(?P<slug>[\w-]+)/comments/',
        'myapp.blog.views.comments')

Or call it from your urlconf directly::

    from myapp.views.comments import BlogComments
    urlpatterns = patterns('',
        (r'^archive/(?P<year>\d+)/(?P<month>\d+)/(?P<day>\d+)/(?P<slug>[\w-]+)/comments/',
        BlogComments()) 

-----------
Usage Hints
-----------

You can use Django decorators if you forgo the class method
approach and use static functions. Obviously, you cannot reference
``self`` if you do this.

Here's a quick hint on possible usage with the above static
function and newforms::

    class TheClassName(RestfulView):
        @staticmethod
        def handle_GET(request, form=YourFormName()):
            # ...

        @staticmethod
        @login_required
        def handle_POST(request):
            form = YourFormName(request.POST)
            if form.is_valid():
                # ...
            else:
                return TheClassName.handle_GET(request, form=form)
"""

from django.http import HttpResponseNotAllowed

class RestfulView(object):
    def __call__(self, request, *args, **kw):
        # try and find a handler for the given HTTP method
        method = request.META['REQUEST_METHOD'].upper()
        handler = getattr(self, 'handle_%s' % method, None)

        if handler is None:
            # compile a list of all our methods and return an HTTP 405
            methods = []
            for x in dir(self):
                if x.startswith('handle_'):
                    methods.append(x[7:])
            return HttpResponseNotAllowed(methods)

        return handler(request, *args, **kw)