tax: float | None = None
    tags: set[str] = set()


@app.post("/items/", tags=["items"])
async def create_item(item: Item) -> Item:
    return item


@app.get("/items/", tags=["items"])
async def read_items():
    return [{"name": "Foo", "price": 42}]


@app.get("/users/", tags=["users"])
async def read_users():

    return user


async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)]):
    user = fake_decode_token(token)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Not authenticated",
            headers={"WWW-Authenticate": "Bearer"},
        )
    return user


async def get_current_active_user(

from fastapi.routing import APIRoute


class ValidationErrorLoggingRoute(APIRoute):
    def get_route_handler(self) -> Callable:
        original_route_handler = super().get_route_handler()

        async def custom_route_handler(request: Request) -> Response:
            try:
                return await original_route_handler(request)
            except RequestValidationError as exc:
                body = await request.body()

from typing import Annotated

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: Annotated[str, Header()]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: Annotated[str, Header()]):
    if x_key != "fake-super-secret-key":

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


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


@app.patch("/items/{item_id}")
async def update_item(item_id: str, item: Item) -> Item:
    stored_item_data = items[item_id]
    stored_item_model = Item(**stored_item_data)

from fastapi import FastAPI
from fastapi.testclient import TestClient

app_default = FastAPI()


@app_default.post("/items/")
async def app_default_post(data: dict):
    return data


app_lax = FastAPI(strict_content_type=False)


@app_lax.post("/items/")
async def app_lax_post(data: dict):
    return data


client_default = TestClient(app_default)
client_lax = TestClient(app_lax)

当你在**大型代码库**中，在**很多*路径操作***里反复使用**相同的依赖**时，这会特别有用。

## 要不要使用 `async`？ { #to-async-or-not-to-async }

由于依赖项也会由 **FastAPI** 调用（与*路径操作函数*相同），因此定义函数时同样的规则也适用。

你可以使用 `async def` 或普通的 `def`。

你可以在普通的 `def` *路径操作函数*中声明 `async def` 的依赖项；也可以在异步的 `async def` *路径操作函数*中声明普通的 `def` 依赖项，等等。

都没关系，**FastAPI** 知道该怎么处理。

/// note | 注意

如果不了解异步，请参阅文档中关于 `async` 和 `await` 的章节：[异步：*“着急了？”*](../../async.md#in-a-hurry)。

///

```Python
with open("file.txt") as file:
    file.read()
```

В последних версиях Python есть также асинхронный менеджер контекста. Его используют с `async with`:

```Python
async with lifespan(app):
    await do_stuff()
```

from fastapi import FastAPI

app = FastAPI()


@app.get("/users/me")
async def read_user_me():
    return {"user_id": "the current user"}


@app.get("/users/{user_id}")
async def read_user(user_id: str):

8. Nota que esta *path operation function* usa `def` regular en lugar de `async def`.

    Como siempre, en FastAPI puedes combinar `def` y `async def` según sea necesario.

    Si necesitas un repaso sobre cuándo usar cuál, revisa la sección _"¿Con prisa?"_ en la documentación sobre [`async` y `await`](../async.md#in-a-hurry).