Is there a way in a ktor client where I can peek the response body without consuming it? `HttpRespon...

# ktor

[Jason Toms]

Is there a way in a ktor client where I can peek the response body without consuming it? HttpResponse.content is marked as internal, but it is exactly what I need since it is an unconsumed ByteReadChannel that lets me use peekTo...is there a good reason this is marked as internal and do you think I could use it anyway, or is there something else I could be using instead?

[Aleksei Tirman [JB]]

You can stream the response body by getting a ByteReadChannel to read from.

[Jason Toms]

Yes, but if I get the ByteReadChannel the body gets consumed. I have a plugin where I want to read the body to respond to certain types or errors, but the response should still get sent out of this plugin. So I am having a problem being able to see a response body both inside and outside of a plugin

[ephemient]

are you running into something like https://youtrack.jetbrains.com/issue/KTOR-4225/HttpResponseValidator-consumes-HTTP-response-body ?

[Jason Toms]

My problem does sound exactly like what the commenter grasseh in there mentioned two months ago. I want to see the response body in my ClientPlugin but if I do, the final response fails to deserialize (because the response is gone)

[Aleksei Tirman [JB]]

You can split the body's ByteReadChannel into two channels to use one of them and return another. Here is an example:

val client = HttpClient(CIO)

val scope = CoroutineScope(coroutineContext)
client.responsePipeline.intercept(HttpResponsePipeline.Receive) { (type, body) ->
    if (body !is ByteReadChannel) return@intercept

    val (first, second) = body.split(scope)
    println(first.toByteArray().size) // Consume first here
    proceedWith(HttpResponseContainer(type, second))
}

client.prepareGet("<https://httpbin.org/get>").execute { // Stream the response body
    println(it.bodyAsText())
}