Class _DefaultLifespan

fastapi/routing.py:242–263

Default lifespan context manager that runs on_startup and on_shutdown handlers. This is a copy of the Starlette _DefaultLifespan class that was removed in Starlette. FastAPI keeps it to maintain backward compatibility with on_startup and on_shutdown event handlers. Ref: https:

class _DefaultLifespan:
    """
    Default lifespan context manager that runs on_startup and on_shutdown handlers.

    This is a copy of the Starlette _DefaultLifespan class that was removed
    in Starlette. FastAPI keeps it to maintain backward compatibility with
    on_startup and on_shutdown event handlers.

    Ref: https://github.com/Kludex/starlette/pull/3117
    """

    def __init__(self, router: "APIRouter") -> None:
        self._router = router

    async def __aenter__(self) -> None:
        await self._router._startup()

    async def __aexit__(self, *exc_info: object) -> None:
        await self._router._shutdown()

    def __call__(self: _T, app: object) -> _T:
        return self


# Cache for endpoint context to avoid re-extracting on every request