class Drupal2SPIPRouter:
    def db_for_read(self, model, **hints):
        if model._meta.app_label == 'drupal':
            return 'drupal'
        return None

    def db_for_write(self, model, **hints):
        return self.db_for_read(model, **hints)

    def allow_relation(self, obj1, obj2, **hints):
        """
        We disallow cross db relations.
        """
        app1, app2 = obj1._meta.app_label, obj2._meta.app_label
        if 'drupal' in [app1, app2]:
            return app1 == app2
        return None

    def allow_migrate(self, db, app_label, model_name=None, **hints):
        """
        We disallow migrations for those db.
        """
        if db == 'drupal':
            return False
        return None