Post Processing Decorator for Flask Smorest - Execute a function after Flask returns response

flask_post_processing.py

class PostProcessingTask:
    def __init__(self, func: Callable[..., None], *args: Any, **kwargs: Any):
        self.func = func
        self.args = args
        self.kwargs = kwargs

    def execute(self) -> None:
        self.func(*self.args, **self.kwargs)


def post_processing(response: Response) -> Response:
    """Provide a way to execute a function AFTER the request has been returned by setting
    request.post_processing with a PostProcessingTask object.

    This is achieved with Werkzeug 'call_on_close' callback on response objects.

    Unlike @app.after_response it:
      - is not meant to modify the request object.
      - trully happen after the request so you don't extend the request delay.
      - won't affect the response if it raise an exception.

    WARNING: if abort is called or an exception is raised during the view execution then the
    post-processing won't happen.

    WARNING: No request context or app context available when the request is executed.

    for more technical details and context checkout:
    https://stackoverflow.com/questions/48994440/execute-a-function-after-flask-returns-response
    """
    if hasattr(request, "post_processing"):
        if not isinstance(request.post_processing, PostProcessingTask):
            raise ValueError()

        response.call_on_close(request.post_processing.execute)

    return response