def get_next_id(self):
        try:
            query = {'_id': 'last_id'}
            update = {'$inc': {'id': 1}}
            fn = self.db.internal.find_and_modify
            row = fn(query, update, upsert=True, new=True)
        except Exception as e:
            raise DatabaseException(e)
        return row['id']
def _getProvenanceAfterMetadata(self, item, meta, user):
        resp = self.request(path='/item/%s/metadata' % item['_id'],
                            method='PUT', user=user, body=json.dumps(meta),
                            type='application/json')
        self.assertStatusOk(resp)
        return self._getProvenance(item, user)