gistfile1.py

from django.utils.http import is_safe_url
from django.core.urlresolvers import reverse
from django.utils.safestring import mark_safe


class WithNextUrlMixin(object):
    """
    This view will use whatever value was submitted as `next` as the success
    url, as long as the url resolves correctly.
    """
    def get_success_url(self):
        return self.get_next_url() or super(WithNextUrlMixin, self).get_success_url()

    def get_next_url(self):
        next = self.request.REQUEST.get('next')
        if next and is_safe_url(next):
            return next

    def get_context_data(self, **kwargs):
        kwargs = super(WithNextUrlMixin, self).get_context_data(**kwargs)
        next = self.get_next_url()
        if next:
            kwargs['next'] = next
            kwargs['next_input'] = mark_safe('<input type="hidden" name="next" value="{0}">'.format(next))
        return kwargs

    @classmethod
    def as_view(cls, *args, **kwargs):
        """
        Wraps View.as_view to add a with_next function on the view object.
        with_next will return the reverse of the current view with the query
        string for the next URL appended.
        """
        view = super(WithNextUrlMixin, cls).as_view(*args, **kwargs)

        def with_next(next_url, args=None, kwargs=None):
            return '{0}?{1}'.format(
                reverse(view, args=args, kwargs=kwargs),
                urllib.urlencode({'next': next_url}),
            )

        view.with_next = with_next

        return view

gistfile2.py

class LoginView(WithNextUrlMixin, ...):
  ...
  

login = LoginView.as_view()


class NeedsLoginView(...):
  def get(self, *args, **kwargs):
    if not self.request.user.is_authenticated():
      return redirect(login.with_next(self.request.path))