Hi all, I'm currently trying to implement an SSE ...

# ktor

[sigmadelta]

Hi all,

I'm currently trying to implement an SSE implemention in Ktor for a Compose Multiplatform client, and more specifically the WASM one using a JS Ktor engine. I'm trying to read out the Cohere Chat Stream API (https://docs.cohere.com/v2/reference/chat-stream) but my request always keeps failing because apparently I'm not allowed to add a request body to an SSE request?

Caused by: JsError: Error from javascript[TypeError: Failed to execute 'fetch' on 'Window': Request with GET/HEAD method cannot have body.

My implementation looks like this:

suspend fun sendCohereChatMessage(msg: String) {
        val chatRequest = ChatRequest(
            stream = true,
            model = "command-r-plus-08-2024",
            messages = listOf(RequestMessage(role = "user", content = msg))
        )

        client.serverSentEvents(
            urlString = "<https://api.cohere.com/v2/chat>",
            request = {
                setBody(chatRequest)
                contentType(ContentType.Application.Json)
            }
        ) {
            incoming.collect { event ->
                println(event)
            }
        }
    }

Does anyone know how to get passed this issue or is it simply not supported?

[Daniel Pitts]

If the error is about a HEAD request, then it seems likely the error is happening elsewhere in your code. Unless there is a bug with the SSE plugin

[Daniel Pitts]

Oh, I missed it might also be a GET. In your request block, make sure you set the method correctly. It should probably be POST

[sigmadelta]

Oh wow, I totally missed that 🙈!

Adding method = <http://HttpMethod.Post|HttpMethod.Post> to the request block fixed the issue indeed.

Thanks a bunch!

[Daniel Pitts]

Glad that worked.