return err
		}
	case !f.Tag.IsEmpty():
		if err := e.EncodeElement(f.Tag, xml.StartElement{Name: xml.Name{Local: "Tag"}}); err != nil {
			return err
		}
	default:
		// Always print Prefix field when both And & Tag are empty
		if err := e.EncodeElement(f.Prefix, xml.StartElement{Name: xml.Name{Local: "Prefix"}}); err != nil {
			return err
		}

		if f.ObjectSizeLessThan > 0 {

		t.Fatalf("failed preload company: %v", err)
	}
	if got.Company.ID == 0 || got.Company.Name != "Belongs-To-Co" {
		t.Fatalf("expected Company assigned, got %+v", got.Company)
	}
}

// Mixed fields + association: update Age and create a pet together
func TestClauseAssociationSetUpdateMixedFieldAndAssociation(t *testing.T) {
	ctx := context.Background()
	user := User{Name: "TestClauseAssociationSetUpdateMixed", Age: 20}

    static_dir: Path = Path(os.getcwd()) / "static"
    print(static_dir)
    static_dir.mkdir(exist_ok=True)
    from docs_src.custom_docs_ui.tutorial002_py39 import app

    with TestClient(app) as client:
        yield client
    static_dir.rmdir()


def test_swagger_ui_html(client: TestClient):
    response = client.get("/docs")
    assert response.status_code == 200, response.text

///

### Pydantic v1 and v2 on the same app { #pydantic-v1-and-v2-on-the-same-app }

It's **not supported** by Pydantic to have a model of Pydantic v2 with its own fields defined as Pydantic v1 models or vice versa.

```mermaid
graph TB
    subgraph "❌ Not Supported"
        direction TB
        subgraph V2["Pydantic v2 Model"]
            V1Field["Pydantic v1 Model"]
        end

def test_fastapi_error(mod: ModuleType):
    client = TestClient(mod.app)
    with pytest.raises(FastAPIError) as exc_info:
        client.get("/items/portal-gun")
    assert "raising an exception and a dependency with yield" in exc_info.value.args[0]


def test_internal_server_error(mod: ModuleType):
    client = TestClient(mod.app, raise_server_exceptions=False)
    response = client.get("/items/portal-gun")

```JSON
{
    "detail": [
        {
            "loc": [
                "query",
                "needy"
            ],
            "msg": "field required",
            "type": "value_error.missing"
        }
    ]
}
```

La présence de `needy` étant nécessaire, vous auriez besoin de l'insérer dans l'URL :

```

        return ["John Doe", "Jane Doe"]

    async def close(self) -> None:
        pass


async def get_client() -> AsyncGenerator[DummyClient, None]:
    client = DummyClient()
    yield client
    await client.close()


Client = Annotated[DummyClient, Depends(get_client)]


@pytest.fixture(name="client")
def client_fixture() -> TestClient:
    app = FastAPI()

    @app.get("/")

    static_dir: Path = Path(os.getcwd()) / "static"
    print(static_dir)
    static_dir.mkdir(exist_ok=True)
    from docs_src.custom_docs_ui.tutorial001_py39 import app

    with TestClient(app) as client:
        yield client
    static_dir.rmdir()


def test_swagger_ui_html(client: TestClient):
    response = client.get("/docs")
    assert response.status_code == 200, response.text

```JSON
{
  "detail": [
    {
      "type": "missing",
      "loc": [
        "query",
        "needy"
      ],
      "msg": "Field required",
      "input": null
    }
  ]
}
```

Da `needy` ein erforderlicher Parameter ist, müssen Sie ihn in der URL setzen:

```
http://127.0.0.1:8000/items/foo-item?needy=sooooneedy
```

本例把标准的 `dataclasses` 直接替换为 `pydantic.dataclasses`：

```{ .python .annotate hl_lines="1  5  8-11  14-17  23-25  28" }
{!../../docs_src/dataclasses_/tutorial003.py!}
```

1. 本例依然要从标准的 `dataclasses` 中导入 `field`；

2. 使用 `pydantic.dataclasses` 直接替换 `dataclasses`；

3. `Author` 数据类包含 `Item` 数据类列表；

4. `Author` 数据类用于 `response_model` 参数；

5. 其它带有数据类的标准类型注解也可以作为请求体；

    本例使用的是 `Item` 数据类列表；