## 사전정의 값

만약 *경로 매개변수*를 받는 *경로 작동*이 있지만, *경로 매개변수*로 가능한 값들을 미리 정의하고 싶다면 파이썬 표준 <abbr title="열거형(Enumeration)">`Enum`</abbr>을 사용할 수 있습니다.

### `Enum` 클래스 생성

`Enum`을 임포트하고 `str`과 `Enum`을 상속하는 서브 클래스를 만듭니다.

`str`을 상속함으로써 API 문서는 값이 `string` 형이어야 하는 것을 알게 되고 이는 문서에 제대로 표시됩니다.

가능한 값들에 해당하는 고정된 값의 클래스 어트리뷰트들을 만듭니다:

```Python hl_lines="1  6-9"
{!../../docs_src/path_params/tutorial005.py!}
```

from pydantic import BaseModel

app = FastAPI()


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


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")

from typing import Optional

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: bool = Optional[None]


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Optional[str] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")

}

// ParseReplicationTS parse http.TimeFormat first
// will try time.RFC3339Nano when parse http.TimeFormat failed
func ParseReplicationTS(str string) (time.Time, error) {
	tm, err := time.Parse(http.TimeFormat, str)
	if tm.IsZero() || err != nil {
		tm, err = time.Parse(time.RFC3339Nano, str)
	}
	return tm, err

from typing import Union

from fastapi import FastAPI, Header
from typing_extensions import Annotated

app = FastAPI()


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

from typing import List, Union

from fastapi import FastAPI, Header
from typing_extensions import Annotated

app = FastAPI()


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

from typing import Annotated

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Annotated[
        Item,
        Body(
            openapi_examples={

from typing import Annotated

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[str, Query(min_length=3)]):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from fastapi import FastAPI, Query
from typing_extensions import Annotated

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[str, Query(min_length=3)] = ...):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from fastapi import FastAPI, HTTPException

app = FastAPI()

items = {"foo": "The Foo Wrestlers"}


@app.get("/items/{item_id}")
async def read_item(item_id: str):
    if item_id not in items:
        raise HTTPException(status_code=404, detail="Item not found")