How do I know whether to use receive_text or receive_bytes?

[WSH032]

Hi, this is a great library!

I've been using this library recently to implement a reverse WebSocket proxy. I establish WebSocket connections with both the client and the target server, acting as an intermediary to pass messages between the two.

However, I've encountered an issue:

Before receiving messages, how can I determine whether to use receive_text or receive_bytes? If I use the wrong method, I get a WebSocketInvalidTypeReceived error.

server.send_text("Hello World!")
# then
client.receive_bytes()  # Boom !

---

Actually, I know that I can achieve what I want by doing the following:

import wsproto
from httpx_ws import WebSocketInvalidTypeReceived, AsyncWebSocketSession


async def receive(self: AsyncWebSocketSession) -> str | bytes:
    event = await self.receive()
    if isinstance(event, wsproto.events.TextMessage):
        return event.data
    elif isinstance(event, wsproto.events.BytesMessage):
        return event.data
    else:
        raise WebSocketInvalidTypeReceived(event)

But this isn't part of the official API, and I'm not certain whether future updates might cause disruptions.

---

I'm a bit confused. Why does receive_bytes only accept bytes, while receive_text only accepts str?

Because I cannot know in advance what type of data will be sent to me from the upstream.

starlette/discussions/2310

Is this due to specific design purposes?

---

If I don't care about the type of message received, is there an officially supported API that allows receiving messages of any type, something like async def receive(self: AsyncWebSocketSession) -> str | bytes: I mentioned above?

And then I can determine the received data type by using isinstance(data, str).

[frankie567]

Well, generally speaking, you know whether your WebSocket sends you a string or bytes; it's part of how it's implemented. So receive_bytes and receive_text are convenient shortcuts.

Obviously, for a proxy, you don't know in advance. Thus, the way you show with plain receive and check the nature of the message is the way to go. It's part of the API, it's documented: https://frankie567.github.io/httpx-ws/reference/httpx_ws/#httpx_ws.AsyncWebSocketSession.receive

[WSH032]

Thanks for your quick response!

It's part of the API, it's documented:

I'm just a bit concerned because it involves wsproto, but wsproto is a dependency of httpx_ws, so I am not sure wsproto is part of httpx_ws API.
I worry that I might be digging a bit too deep into the lower-level APIs.

Thank you for your reply. I think the question has been resolved. 😄