def foo(req: Model) -> dict[str, str | None]:
        return {
            "value": req.value or None,
            "embedded_value": req.embedded_model.value or None,
        }

    client = TestClient(app)

    response = client.post("/", json={})
    assert response.status_code == 200, response.text
    assert response.json() == {
        "value": None,
        "embedded_value": None,
    }

    response2 = client.post(

`responses` parametrenizde açıkça farklı bir media type belirtmediğiniz sürece FastAPI, response'un ana response class'ı ile aynı media type'a sahip olduğunu varsayar (varsayılan `application/json`).

Ancak media type'ı `None` olan özel bir response class belirttiyseniz, FastAPI ilişkili bir model'i olan tüm ek response'lar için `application/json` kullanır.

///

## Bilgileri Birleştirme { #combining-information }

        // Test that empty args (except for goal) work correctly
        String[] args = {"apply"};
        CommonsCliUpgradeOptions options = CommonsCliUpgradeOptions.parse(args);

        // None of the optional flags should be present
        assertFalse(options.plugins().isPresent(), "--plugins should not be present by default");
        assertFalse(options.all().isPresent(), "--all should not be present by default");

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


class User(BaseModel):
    username: str
    full_name: str | None = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item, user: User):

    name: str | None = None
    call: Callable[..., Any] | None = None
    request_param_name: str | None = None
    websocket_param_name: str | None = None
    http_connection_param_name: str | None = None
    response_param_name: str | None = None
    background_tasks_param_name: str | None = None
    security_scopes_param_name: str | None = None
    own_oauth_scopes: list[str] | None = None

app = FastAPI()


class Image(BaseModel):
    url: HttpUrl
    name: str


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    tags: set[str] = set()
    images: list[Image] | None = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):
    results = {"item_id": item_id, "item": item}

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


class User(BaseModel):
    username: str
    full_name: str | None = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: int, item: Item, user: User, importance: Annotated[int, Body()]
):

@app.post("/optional-list-bytes")
async def read_optional_list_bytes(p: Annotated[list[bytes] | None, File()] = None):
    return {"file_size": [len(file) for file in p] if p else None}


@app.post("/optional-list-uploadfile")
async def read_optional_list_uploadfile(
    p: Annotated[list[UploadFile] | None, File()] = None,
):
    return {"file_size": [file.size for file in p] if p else None}


@pytest.mark.parametrize(
    "path",
    [

class ReviewNode(BaseModel):
    author: Author | None = None
    state: str


class Reviews(BaseModel):
    nodes: list[ReviewNode]


class PullRequestNode(BaseModel):
    number: int
    labels: Labels
    author: Author | None = None
    title: str
    createdAt: datetime
    lastEditedAt: datetime | None = None
    updatedAt: datetime | None = None
    state: str
    reviews: Reviews

예를 들어, 어떤 값이 `str` 또는 `None`이 될 수 있다고 선언할 수 있습니다:

```python
from typing import Union


def say_hi(name: Union[str, None]):
        print(f"Hi {name}!")
```

`typing`에는 `None`이 될 수 있음을 선언하는 축약형으로 `Optional`도 있습니다.

아주 개인적인 관점에서의 팁입니다:

- 🚨 `Optional[SomeType]` 사용은 피하세요
- 대신 ✨ **`Union[SomeType, None]`를 사용하세요** ✨.