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 get_primary_domain(self):
        """
        Returns the primary domain of the tenant
        """
        try:
            domain = self.domains.get(is_primary=True)
            return domain
        except get_tenant_domain_model().DoesNotExist:
            return None