with Session(engine) as session:
        yield session


def get_user(user_id: int, session: Annotated[Session, Depends(get_session)]):
    user = session.get(User, user_id)
    if not user:
        raise HTTPException(status_code=403, detail="Not authorized")


def generate_stream(query: str):
    for ch in query:
        yield ch
        time.sleep(0.1)


@app.get("/generate", dependencies=[Depends(get_user)])

    serves mainly as a marker and sets the correct `Content-Type`.
    """

    media_type = "text/event-stream"


def _check_id_no_null(v: str | None) -> str | None:
    if v is not None and "\0" in v:
        raise ValueError("SSE 'id' must not contain null characters")
    return v


class ServerSentEvent(BaseModel):
    """Represents a single Server-Sent Event.

    When `yield`ed from a *path operation function* that uses

        content={"message": f"Oops! {exc.name} did something. There goes a rainbow..."},
    )


@app.get("/unicorns/{name}")
async def read_unicorn(name: str):
    if name == "yolo":
        raise UnicornException(name=name)

{* ../../docs_src/security/tutorial005_an_py310.py hl[47,117:129] *}

## Verify the `scopes` { #verify-the-scopes }

We now verify that all the scopes required, by this dependency and all the dependants (including *path operations*), are included in the scopes provided in the token received, otherwise raise an `HTTPException`.

    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

    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

    "isbn-9781439512982": "Isaac Asimov: The Complete Stories, Vol. 2",
}


def check_valid_id(id: str):
    if not id.startswith(("isbn-", "imdb-")):
        raise ValueError('Invalid ID format, it must start with "isbn-" or "imdb-"')
    return id


@app.get("/items/")
async def read_items(
    id: Annotated[str | None, AfterValidator(check_valid_id)] = None,
):
    if id:

通常使用している依存関係の*関数*と同じものを使用できます。

### 依存関係の要件 { #dependency-requirements }

これらはリクエストの要件（ヘッダーのようなもの）やその他のサブ依存関係を宣言できます:

{* ../../docs_src/dependencies/tutorial006_an_py310.py hl[8,13] *}

### 例外の発生 { #raise-exceptions }

これらの依存関係は、通常の依存関係と同じように例外を`raise`できます:

{* ../../docs_src/dependencies/tutorial006_an_py310.py hl[10,15] *}

### 戻り値 { #return-values }

そして、値を返すことも返さないこともできますが、値は使われません。

class DictablePet(Pet):
    def __iter__(self):
        return ((k, v) for k, v in self.__dict__.items())


class Unserializable:
    def __iter__(self):
        raise NotImplementedError()

    @property
    def __dict__(self):
        raise NotImplementedError()


class RoleEnum(Enum):
    admin = "admin"
    normal = "normal"


class ModelWithConfig(BaseModel):
    role: RoleEnum | None = None

async def get_cookie_or_token(
    websocket: WebSocket,
    session: str | None = Cookie(default=None),
    token: str | None = Query(default=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,