http://chriskief.com/2012/12/14/django-class-based-views/

mixins.py

from django.http import HttpResponseRedirect
from django.core.urlresolvers import reverse


class RequireSignIn(object):

    def dispatch(self, request, *args, **kwargs):

        if not request.user.is_authenticated():
            url = '{0}?next={1}'.format(reverse('signin'), request.path)
            return HttpResponseRedirect(url)

        return super(RequireSignIn, self).dispatch(request, *args, **kwargs)