async def dep0(response: Response):
    response.headers["x-level0"] = "True"


async def dep1(response: Response):
    response.headers["x-level1"] = "True"


async def dep2(response: Response):
    response.headers["x-level2"] = "True"


async def dep3(response: Response):
    response.headers["x-level3"] = "True"


async def dep4(response: Response):

    limit: int = Field(100, gt=0, le=100)
    offset: int = Field(0, ge=0)
    order_by: Literal["created_at", "updated_at"] = "created_at"
    tags: list[str] = []


@app.get("/items/")
async def read_items(filter_query: Annotated[FilterParams, Query()]):

//// tab | Python 3.10+

```Python hl_lines="1"
async def needy_dependency(fresh_value: Annotated[str, Depends(get_value, use_cache=False)]):
    return {"fresh_value": fresh_value}
```

////

//// tab | Python 3.10+ nicht annotiert

/// tip | Tipp

Bevorzugen Sie die `Annotated`-Version, falls möglich.

///

```Python hl_lines="1"
async def needy_dependency(fresh_value: str = Depends(get_value, use_cache=False)):

    tags: set[str] = set()


@app.post(
    "/items/",
    summary="Create an item",
    description="Create an item with all the information, name, description, price, tax and a set of unique tags",
)
async def create_item(item: Item) -> Item:

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: str | None = Query(
        default=None,
        alias="item-query",
        title="Query string",
        description="Query string for the items to search in the database that have a good match",
        min_length=3,
        max_length=50,
        pattern="^fixedquery$",
        deprecated=True,
    ),
):

    description: str | None = Field(default=None, examples=["A very nice Item"])
    price: float = Field(examples=[35.4])
    tax: float | None = Field(default=None, examples=[3.2])


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

É apenas uma função padrão que pode receber parâmetros.

Pode ser uma função `async def` ou um `def` normal, o **FastAPI** saberá como lidar com isso corretamente.

Neste caso, a função da tarefa escreverá em um arquivo (simulando o envio de um e-mail).

E como a operação de escrita não usa `async` e `await`, definimos a função com um `def` normal:

{* ../../docs_src/background_tasks/tutorial001_py310.py hl[6:9] *}

Але в багатьох випадках читання файлу або схожого на файл об'єкта блокує виконання.

///

Щоб уникнути блокування циклу подій, просто оголосіть функцію операції шляху зі звичайним `def` замість `async def`. Тоді FastAPI виконуватиме її в працівнику пулу потоків, щоб не блокувати головний цикл.

{* ../../docs_src/stream_data/tutorial002_py310.py ln[30:34] hl[31] *}

/// tip | Порада

    assertThat(response1.body.source().readUtf8(3)).isEqualTo("ABC")
    assertThat(response2.body.source().readUtf8(3)).isEqualTo("GHI")
    assertThat(response1.body.source().readUtf8(3)).isEqualTo("DEF")
    assertThat(response2.body.source().readUtf8(3)).isEqualTo("JKL")
    val c0e0 = server.takeRequest()
    assertThat(c0e0.connectionIndex).isEqualTo(0)
    assertThat(c0e0.exchangeIndex).isEqualTo(0)

    images: list[Image] | None = None


class Offer(BaseModel):
    name: str
    description: str | None = None
    price: float
    items: list[Item]


@app.post("/offers/")
async def create_offer(offer: Offer):