from fastapi import FastAPI, Path
from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],
    q: Union[str, None] = None,

            script {
                // Because we exclude tests in `distributions-integ-tests` below, `@Flaky` won't work in that subproject.
                // Here we check the existence of `@Flaky` annotation to make sure nobody use that annotation in `distributions-integ-tests` subproject.
                name = "MAKE_SURE_NO_@FLAKY_IN_DISTRIBUTIONS_INTEG_TESTS"
                executionMode = BuildStep.ExecutionMode.ALWAYS

from typing import Any, Callable

from starlette.background import BackgroundTasks as StarletteBackgroundTasks
from typing_extensions import Annotated, Doc, ParamSpec

P = ParamSpec("P")


class BackgroundTasks(StarletteBackgroundTasks):
    """
    A collection of background tasks that will be called after a response has been
    sent to the client.

    Read more about it in the

```

////

//// tab | Python 3.10+ non-Annotated

/// tip

尽可能选择使用 `Annotated` 的版本。

///

```Python hl_lines="18-23"
{!> ../../docs_src/schema_extra_example/tutorial003_py310.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip

尽可能选择使用 `Annotated` 的版本。

///

```Python hl_lines="20-25"

from typing_extensions import Annotated


def say_hello(name: Annotated[str, "this is just metadata"]) -> str:

from typing import Annotated


def say_hello(name: Annotated[str, "this is just metadata"]) -> str:

from typing import List

from fastapi import FastAPI, File, UploadFile
from fastapi.responses import HTMLResponse
from typing_extensions import Annotated

app = FastAPI()


@app.post("/files/")
async def create_files(files: Annotated[List[bytes], File()]):
    return {"file_sizes": [len(file) for file in files]}


@app.post("/uploadfiles/")
async def create_upload_files(files: List[UploadFile]):

```

////

//// tab | Python 3.8+

```Python hl_lines="5  13  21"
{!> ../../docs_src/dependencies/tutorial008_an.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip | 提示

如果可以，请尽量使用 `Annotated` 版本。

///

```Python hl_lines="4  12  20"
{!> ../../docs_src/dependencies/tutorial008.py!}
```

////

所有这些依赖都可以使用 `yield`。

from typing import Annotated

from fastapi import Cookie, FastAPI

app = FastAPI()


@app.get("/items/")
async def read_items(ads_id: Annotated[str | None, Cookie()] = None):

from typing import Annotated

from fastapi import FastAPI, Header

app = FastAPI()


@app.get("/items/")
async def read_items(user_agent: Annotated[str | None, Header()] = None):