def test_get_item_oo_field(self):
        """
        REST Api: Test get item with O-O related field
        """
        client = self.app.test_client()
        token = self.login(client, USERNAME_ADMIN, PASSWORD_ADMIN)

        with model_oo_parent_data(self.appbuilder.session, 1) as models:
            model_id = models[0].id
            rv = self.auth_client_get(
                client, token, f"api/v1/modelooparentapi/{model_id}"
            )
            data = json.loads(rv.data.decode("utf-8"))
            self.assertEqual(rv.status_code, 200)
            self.assertEqual(
                data[API_RESULT_RES_KEY],
                {
                    "field_string": "text0",
                    "child": {"field_string": "text0.child", "id": models[0].child.id},
                },
            )

        REST Api: Test get item with O-O related field
        
tests/test_api.py