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


async def get_query_token(token: str):
    if token != "jessica":

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":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key

    raw_body = await request.body()
    try:
        data = yaml.safe_load(raw_body)
    except yaml.YAMLError:
        raise HTTPException(status_code=422, detail="Invalid YAML")
    try:
        item = Item.model_validate(data)
    except ValidationError as e:
        raise HTTPException(status_code=422, detail=e.errors(include_url=False))

from fastapi import FastAPI, HTTPException

app = FastAPI()

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


@app.get("/items-header/{item_id}")
async def read_item_header(item_id: str):
    if item_id not in items:
        raise HTTPException(
            status_code=404,
            detail="Item not found",
            headers={"X-Error": "There goes my error"},
        )

➡️ 💬 👆 ✔️ 🛃 ⚠ `UnicornException` 👈 👆 (⚖️ 🗃 👆 ⚙️) 💪 `raise`.

& 👆 💚 🍵 👉 ⚠ 🌐 ⏮️ FastAPI.

👆 💪 🚮 🛃 ⚠ 🐕‍🦺 ⏮️ `@app.exception_handler()`:

```Python hl_lines="5-7  13-18  24"
{!../../../docs_src/handling_errors/tutorial003.py!}
```

📥, 🚥 👆 📨 `/unicorns/yolo`, *➡ 🛠️* 🔜 `raise` `UnicornException`.

✋️ ⚫️ 🔜 🍵 `unicorn_exception_handler`.

    print(f"OMG! The client sent invalid data!: {exc}")
    return await request_validation_exception_handler(request, exc)


@app.get("/items/{item_id}")
async def read_item(item_id: int):
    if item_id == 3:
        raise HTTPException(status_code=418, detail="Nope! I don't like 3.")

    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )
    if not (is_correct_username and is_correct_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Basic"},
        )
    return credentials.username

あなた（または使用しているライブラリ）が`raise`するかもしれないカスタム例外`UnicornException`があるとしましょう。

そして、この例外をFastAPIでグローバルに処理したいと思います。

カスタム例外ハンドラを`@app.exception_handler()`で追加することができます:

```Python hl_lines="5 6 7  13 14 15 16 17 18  24"
{!../../../docs_src/handling_errors/tutorial003.py!}
```

ここで、`/unicorns/yolo`をリクエストすると、*path operation*は`UnicornException`を`raise`します。

しかし、これは`unicorn_exception_handler`で処理されます。

async def get_cookie_or_token(
    websocket: WebSocket,
    session: Annotated[str | None, Cookie()] = None,
    token: Annotated[str | None, Query()] = None,
):
    if session is None and token is None:
        raise WebSocketException(code=status.WS_1008_POLICY_VIOLATION)
    return session or token


@app.websocket("/items/{item_id}/ws")
async def websocket_endpoint(
    *,
    websocket: WebSocket,
    item_id: str,

    async def __call__(self, request: Request) -> Optional[str]:
        authorization = request.headers.get("Authorization")
        if not authorization:
            if self.auto_error:
                raise HTTPException(
                    status_code=HTTP_403_FORBIDDEN, detail="Not authenticated"
                )
            else:
                return None
        return authorization