'Returns a dictionary mapping each of the given IDs to the object with
that ID.'

def in_bulk(self, id_list):

    if (not id_list):
        return {}
    qs = self._clone()
    qs.add_filter(('pk__in', id_list))
    qs._clear_ordering(force_empty=True)
    return dict([(obj._get_pk_val(), obj) for obj in qs])
