'Get the queryset to look an object up against. May not be called if
`get_object` is overridden.'

def get_queryset(self):

    if (self.queryset is None):
        if self.model:
            return self.model._default_manager.all()
        else:
            raise ImproperlyConfigured((u'%(cls)s    is    missing    a    queryset.    Define    %(cls)s.model,    %(cls)s.queryset,    or    override    %(cls)s.get_queryset().' % {u'cls': self.__class__.__name__}))
    return self.queryset._clone()
