try:
    from fastapi_cli.cli import main as cli_main

except ImportError:  # pragma: no cover
    cli_main = None  # type: ignore


def main() -> None:
    if not cli_main:  # type: ignore[truthy-function]
        message = 'To use the fastapi command, please install "fastapi[standard]":\n\n\tpip install "fastapi[standard]"\n'
        print(message)
        raise RuntimeError(message)  # noqa: B904

```

기본값 `None`을 `Query(None)`으로 바꿔야 하므로, `Query`의 첫 번째 매개변수는 기본값을 정의하는 것과 같은 목적으로 사용됩니다.

그러므로:

```Python
q: Optional[str] = Query(None)
```

...위 코드는 아래와 동일하게 매개변수를 선택적으로 만듭니다:

```Python
q: Optional[str] = None
```

하지만 명시적으로 쿼리 매개변수를 선언합니다.

/// info | "정보"

FastAPI는 다음 부분에 관심이 있습니다:

```Python
= None
```

또는:

```Python
= Query(None)

		if waypointName == "" {
			waypointName = constants.DefaultNamespaceWaypoint
		} else if waypointName == "none" {
			return nil, fmt.Errorf("invalid name provided for waypoint, 'none' is a reserved value")
		}
		gw := gateway.Gateway{
			TypeMeta: metav1.TypeMeta{
				Kind:       gvk.KubernetesGateway_v1.Kind,
				APIVersion: gvk.KubernetesGateway_v1.GroupVersion(),

    assert response.status_code == 200, response.text
    assert response.json() == {"name": "Wrestlers", "size": None}


def test_create():
    response = client.put("/items/red", json={"name": "Chillies"})
    assert response.status_code == 201, response.text

    assert response.status_code == 200, response.text
    assert response.json() == {"name": "Wrestlers", "size": None}


def test_create():
    response = client.put("/items/red", json={"name": "Chillies"})
    assert response.status_code == 201, response.text

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        Union[str, None],
        Query(
            title="Query string",
            description="Query string for the items to search in the database that have a good match",
            min_length=3,
        ),
    ] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

@app.put("/items/{item_id}")
async def read_items(
    item_id: UUID,
    start_datetime: datetime = Body(),
    end_datetime: datetime = Body(),
    process_after: timedelta = Body(),
    repeat_at: time | None = Body(default=None),
):
    start_process = start_datetime + process_after
    duration = end_datetime - start_process
    return {
        "item_id": item_id,
        "start_datetime": start_datetime,

  rules:
  - apiGroups:
    - metallb.io
    apiVersions:
    - v1beta2
    operations:
    - CREATE
    - UPDATE
    resources:
    - bgppeers
  sideEffects: None
- admissionReviewVersions:
  - v1
  clientConfig:
    service:
      name: webhook-service
      namespace: metallb-system
      path: /validate-metallb-io-v1beta1-bfdprofile
  failurePolicy: Fail

 * future.addListener(new Runnable() {
 *   public void run() {
 *     processedCount.incrementAndGet();
 *     inFlight.remove(name);
 *     lastProcessed.set(name);
 *     logger.info("Done with {0}", name);
 *   }
 * }, executor);
 * }</pre>
 *
 * <h3>How to get an instance</h3>
 *
 * <p>We encourage you to return {@code ListenableFuture} from your methods so that your users can

Isso não é uma limitação do **FastAPI**, é parte do protocolo HTTP.

///

## Upload de Arquivo Opcional

Você pode tornar um arquivo opcional usando anotações de tipo padrão e definindo um valor padrão de `None`:

{* ../../docs_src/request_files/tutorial001_02_an_py310.py hl[9,17] *}

## `UploadFile` com Metadados Adicionais

Você também pode usar `File()` com `UploadFile`, por exemplo, para definir metadados adicionais: