Processing Request Headers

Is your feature request related to a problem? Please describe.
When handling invocation requests, I need a reliable mechanism to parse specific headers and pass them to the handler function. I have not found a recommended approach for achieving this within the current framework. While I can implement a Starlette middleware to populate request.state, this state is not accessible within my handler.

Could you please advise on the best practice for accomplishing this?

Describe the solution you'd like
I would like to have the ability to pass request.state (or a similar context containing parsed headers) directly to the handler function. I have included a relevant code snippet below to illustrate the change that would address this need.

Describe alternatives you've considered

• Overriding the internal _build_request_context method, although I am hesitant to do so since it is not intended for external use.
• Adding an additional route via app.routes.append, but this approach requires rewriting significant portions of the existing _handle_invocation logic, which is not ideal.

Additional context
Please see the code snippet below for reference:

    async def _invoke_handler(self, handler, request_context, takes_context, payload):
        try:
            args = (payload, request_context) if takes_context else (payload,)

            if asyncio.iscoroutinefunction(handler):
                return await handler(*args)
            else:
                loop = asyncio.get_event_loop()
                return await loop.run_in_executor(None, handler, *args)

首先阅读内部的 _build_request_context 和 _handle_invocation 路径，然后将其与 issue 中提议的 _invoke_handler 签名进行比较。确定当前解析后的请求标头和 request.state 是如何表示的，以及所请求的 handler context 是否适合该 framework。完成的标准是有一个经 maintainer 批准的方法，并且为 invocation handlers 明确定义行为并提供覆盖。