"baz": {"name": "Baz", "description": None, "price": 50.2, "tax": 10.5, "tags": []},
}


@app.get("/items/{item_id}", response_model=Item, response_model_exclude_unset=True)
async def read_item(item_id: str):

from fastapi import FastAPI
from fastapi.responses import UJSONResponse

app = FastAPI()


@app.get("/items/", response_class=UJSONResponse)
async def read_items():

Mais dans de nombreux cas, la lecture d'un fichier ou d'un objet de type fichier bloquera.

///

Pour éviter de bloquer la boucle d'événements, vous pouvez simplement déclarer la *fonction de chemin d'accès* avec un `def` classique au lieu de `async def`. Ainsi, FastAPI l'exécutera dans un worker de pool de threads, afin d'éviter de bloquer la boucle principale.

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

/// tip | Astuce

//// 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+ без Annotated

/// tip | Подсказка

Предпочтительнее использовать версию с аннотацией, если это возможно.

///

```Python hl_lines="1"

from fastapi import FastAPI, Request

app = FastAPI()


@app.get("/items/{item_id}")
def read_root(item_id: str, request: Request):
    client_host = request.client.host

你可以跳过这一部分。

///

有一种替代方法可以定义在**启动**和**关闭**期间执行的逻辑。

你可以定义在应用启动前或应用关闭时需要执行的事件处理器（函数）。

事件函数既可以声明为异步函数（`async def`），也可以声明为普通函数（`def`）。

### `startup` 事件 { #startup-event }

使用事件 `"startup"` 声明一个在应用启动前运行的函数：

{* ../../docs_src/events/tutorial001_py310.py hl[8] *}

本例中，`startup` 事件处理器函数为项目“数据库”（只是一个 `dict`）提供了一些初始值。

    size: float


class ItemV2(BaseModelV2):
    name: str
    description: str | None = None
    size: float


app = FastAPI()


@app.post("/items/", response_model=ItemV2)
async def create_item(item: Item):

//// 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+ non annoté

/// tip | Astuce

Privilégiez la version `Annotated` si possible.

///

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

//// 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+ non-Annotated

/// tip | Dica

Utilize a versão com `Annotated` se possível.

///

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

from datetime import datetime, time, timedelta
from uuid import UUID

from fastapi import Body, FastAPI

app = FastAPI()


@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