def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def _swdb_group_remove(self, group_id, pkg_types, pkgs):
        if not self._base.history.group.get(group_id):
            self._raise_or_warn(self._ignore_installed, _("Group id '%s' is not installed.") % group_id)
            return

        swdb_group = self._create_swdb_group(group_id, pkg_types, pkgs)

        if swdb_group is not None:
            self._base.history.group.remove(swdb_group)