因此，即便上述代码没有显式使用 Pydantic，FastAPI 仍会使用 Pydantic 把标准数据类转换为 Pydantic 数据类（`dataclasses`）。

并且，它仍然支持以下功能：

* 数据验证
* 数据序列化
* 数据存档等

数据类的和运作方式与 Pydantic 模型相同。实际上，它的底层使用的也是 Pydantic。

/// info | "说明"

注意，数据类不支持 Pydantic 模型的所有功能。

因此，开发时仍需要使用 Pydantic 模型。

但如果数据类很多，这一技巧能给 FastAPI 开发 Web API 增添不少助力。🤓

///

## `response_model` 使用数据类

在 `response_model` 参数中使用 `dataclasses`：

    ]


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/dict": {
                "get": {
                    "summary": "Read Dict",
                    "operationId": "read_dict_dict_get",

labels.menu_group=Group
labels.menu_suggest=Suggest
labels.menu_suggest_word=Suggest Word
labels.menu_elevate_word=Additional Word
labels.menu_bad_word=Bad Word
labels.menu_system_log=System Info
labels.menu_system_info=Config Info
labels.menu_crawling_info=Crawling Info
labels.menu_log=Log Files
labels.menu_jobLog=Job Log
labels.menu_searchLog=Search Log
labels.menu_failure_url=Failure URL
labels.menu_search_list=Search

def test_openapi_schema(client: TestClient):
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/items/{item_id}": {
                "put": {
                    "responses": {
                        "200": {

@needs_py39
def test_openapi_schema(client: TestClient):
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/files/": {
                "post": {
                    "responses": {
                        "200": {

@needs_py39
def test_openapi_schema(client: TestClient):
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/login/": {
                "post": {
                    "responses": {
                        "200": {

	routeDump, err := w.GetRouteConfigDump()
	if err != nil {
		return nil, err
	}
	drc := routeDump.GetDynamicRouteConfigs()
	// Support v2 or v3 in config dump. See ads.go:RequestedTypes for more info.
	for i := range drc {
		drc[i].RouteConfig.TypeUrl = v3.RouteType
	}
	sort.Slice(drc, func(i, j int) bool {
		r := &route.RouteConfiguration{}
		err = drc[i].RouteConfig.UnmarshalTo(r)
		if err != nil {

    }
    val urlConnection2 = server.url("/").toUrl().openConnection()
    val in2 = urlConnection2.getInputStream()
    assertThat(in2.read()).isEqualTo('D'.code)
    assertThat(in2.read()).isEqualTo('E'.code)
    assertThat(in2.read()).isEqualTo('F'.code)
    assertThat(in2.read()).isEqualTo(-1)
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(0)

      // Expected.
    }
    val urlConnection2 = server.url("/").toUrl().openConnection()
    val in2 = urlConnection2!!.getInputStream()
    assertThat(in2!!.read()).isEqualTo('D'.code)
    assertThat(in2.read()).isEqualTo('E'.code)
    assertThat(in2.read()).isEqualTo('F'.code)
    assertThat(in2.read()).isEqualTo(-1)
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(0)

```Python hl_lines="6"
{!../../docs_src/events/tutorial002.py!}
```

Hier schreibt die `shutdown`-Eventhandler-Funktion eine Textzeile `"Application shutdown"` in eine Datei `log.txt`.

/// info

In der Funktion `open()` bedeutet `mode="a"` „append“ („anhängen“), sodass die Zeile nach dem, was sich in dieser Datei befindet, hinzugefügt wird, ohne den vorherigen Inhalt zu überschreiben.

///

/// tip | "Tipp"