| from typing import Optional | |
| from fastapi.concurrency import AsyncExitStack | |
| from starlette.types import ASGIApp, Receive, Scope, Send | |
| class AsyncExitStackMiddleware: | |
| def __init__(self, app: ASGIApp, context_name: str = "fastapi_astack") -> None: | |
| self.app = app | |
| self.context_name = context_name | |
| async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None: | |
| dependency_exception: Optional[Exception] = None | |
| async with AsyncExitStack() as stack: | |
| scope[self.context_name] = stack | |
| try: | |
| await self.app(scope, receive, send) | |
| except Exception as e: | |
| dependency_exception = e | |
| raise e | |
| if dependency_exception: | |
| # This exception was possibly handled by the dependency but it should | |
| # still bubble up so that the ServerErrorMiddleware can return a 500 | |
| # or the ExceptionMiddleware can catch and handle any other exceptions | |
| raise dependency_exception | |