class ModelWithDatetimeField(BaseModel):
        dt_field: datetime

        @field_serializer("dt_field")
        def serialize_datetime(self, dt_field: datetime):
            return dt_field.replace(microsecond=0, tzinfo=timezone.utc).isoformat()

    app = FastAPI()
    model = ModelWithDatetimeField(dt_field=datetime(2019, 1, 1, 8))

    @app.get("/model", response_model=ModelWithDatetimeField)
    def get_model():

    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": {
            "/info": {
                "get": {
                    "operationId": "info_info_get",
                    "responses": {
                        "200": {

Sie könnten das beispielsweise verwenden, um Metadaten für eine Frontend-Benutzeroberfläche usw. hinzuzufügen.

///

/// info | Info

OpenAPI 3.1.0 (verwendet seit FastAPI 0.99.0) hat Unterstützung für `examples` hinzugefügt, was Teil des **JSON Schema** Standards ist.

    class ModelWithCustomEncoder(BaseModel):
        dt_field: datetime

        @field_serializer("dt_field")
        def serialize_dt_field(self, dt):
            return dt.replace(microsecond=0, tzinfo=timezone.utc).isoformat()

    class ModelWithCustomEncoderSubclass(ModelWithCustomEncoder):
        pass

    model = ModelWithCustomEncoder(dt_field=datetime(2019, 1, 1, 8))

    mod = importlib.import_module(f"docs_src.settings.{request.param}")
    return mod.app


def test_settings(app):
    client = TestClient(app)
    response = client.get("/info")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "app_name": "Awesome API",
        "admin_email": "******@****.***",
        "items_per_user": 50,

def test_openapi_schema():
    response = client.get("/api/v1/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/": {
                "get": {
                    "summary": "Read Items",

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

* «/// check»: «/// check | Testen»
* «/// danger»: «/// danger | Gefahr»
* «/// info»: «/// info | Info»
* «/// note | Technical Details»: «/// note | Technische Details»
* «/// note»: «/// note | Hinweis»
* «/// tip»: «/// tip | Tipp»
* «/// warning»: «/// warning | Achtung»
* «you»: «Sie»
* «your»: «Ihr»

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": {
            "/items/": {
                "get": {
                    "summary": "Read Items",

def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == snapshot(
        {
            "openapi": "3.1.0",
            "info": {"title": "FastAPI", "version": "0.1.0"},
            "servers": [
                {"url": "/", "description": "Default, relative server"},
                {