gistfile1.py

class ProjectMixin(object):
    project_url_pk = 'project_id'
    project = None

    def dispatch(self, request, *args, **kwargs):
        self.project = get_object_or_404(Project, pk=kwargs.get(self.project_url_pk))
        return super(ProjectMixin, self).dispatch(request, *args, **kwargs)

    def get_context_data(self, **kwargs):
        context = super(ProjectMixin, self).get_context_data(**kwargs)
        context.update({'project': self.project})
        return context

class MilestonesView(ProjectMixin, generic.ListView):
    model = models.Milestone