*パスパラメータ*を受け取る *path operation* をもち、有効な*パスパラメータ*の値を事前に定義したい場合は、標準のPython <abbr title="Enumeration - 列挙型">`Enum`</abbr> を利用できます。

### `Enum` クラスの作成 { #create-an-enum-class }

`Enum` をインポートし、 `str` と `Enum` を継承したサブクラスを作成します。

`str` を継承することで、APIドキュメントは値が `string` 型でなければいけないことを知り、正確にレンダリングできるようになります。

そして、固定値のクラス属性を作ります。すると、その値が使用可能な値となります:

{* ../../docs_src/path_params/tutorial005_py310.py hl[1,6:9] *}

/// tip | 豆知識

from fastapi import FastAPI, Header

app = FastAPI()


@app.get("/items/")
async def read_items(
    strange_header: str | None = Header(default=None, convert_underscores=False),
):

from fastapi import APIRouter, Body

router = APIRouter()


@router.post("/compute/")
def compute(a: int = Body(), b: str = Body()):

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):

from typing import Annotated

from fastapi import FastAPI, Header

app = FastAPI()


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

///

## Tags { #tags }

You can add tags to your *path operation*, pass the parameter `tags` with a `list` of `str` (commonly just one `str`):

{* ../../docs_src/path_operation_configuration/tutorial002_py310.py hl[15,20,25] *}

They will be added to the OpenAPI schema and used by the automatic documentation interfaces:

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):

from fastapi.exceptions import FastAPIDeprecationWarning
from fastapi.responses import ORJSONResponse, UJSONResponse
from fastapi.testclient import TestClient
from pydantic import BaseModel


class Item(BaseModel):
    name: str
    price: float


# ORJSON


def _make_orjson_app() -> FastAPI:
    with warnings.catch_warnings():
        warnings.simplefilter("ignore", FastAPIDeprecationWarning)

from fastapi import FastAPI
from pydantic_settings import BaseSettings


class Settings(BaseSettings):
    openapi_url: str = "/openapi.json"


settings = Settings()

app = FastAPI(openapi_url=settings.openapi_url)


@app.get("/")
def root():