Hi guys, I'm trying to create a simple logging Fea...

# ktor

[legzo]

Hi guys, I'm trying to create a simple logging Feature around client calls (using Apache as engine)
I looked into JsonFeature and HttpPlainText as inspiration, and managed to log output requests bodies (if present) and input responses.
But, logging the responses consumes the stream, and I have no clue about how to write again the raw content to the response, for the following features (such as Json serialization..) as the HttpResponse.content is a ByteReadChannel (so readonly..)

[e5l]

You could try to intercept replace response ByteReadChannel with new one from:
reader(...) { ... } or writer(...) { ... }

[e5l]

and perform piping and logging inside the block

[e5l]

JsonFeature expects specific body content type.

[legzo]

Yes, that is what I used to do when in Java and dealing with CXF interceptors : logging consumed the stream, so I had to pipe it to another writer

[legzo]

But I don't know how to write it back

[e5l]

https://github.com/ktorio/ktor-samples

[e5l]

You could take a look at the reverse-proxy sample.

[legzo]

huhhh I might be dumb be which one would it be ?

[Jonas Bark]

inside other/reverse-proxy

[legzo]

Thanks !

[legzo]

I can't quite understand what needs to be done...
In order to get my response marshalled from Json to Object, I need to do something like

proceedWith(HttpResponseContainer(info, message))

[legzo]

right ?

[legzo]

But I can't figure out what the type of message should be in this case

[e5l]

Something like this:

proceedWith(HttpResponseContainer(info, channel))

[legzo]

with channel being a WriteChannelContent ?
because I just tried passing an anonymous WriteChannelContent with an overriden writeTo() like in the example

[e5l]

ByteReadChannel

[legzo]

but I still get No transformation found: class com.xxx.yyy.LoggingFeature$Feature$install$2$res$1 -> class com.xxx.yyy.MyModel

[legzo]

I can't make it work with the ByteReadChannel either : even without consuming the stream : No transformation found: class kotlinx.coroutines.io.ByteBufferChannel -> class com.xxx.yyy.MyModel

[legzo]

Doing just:

val byteReadChannel = response.content
                proceedWith(HttpResponseContainer(info, byteReadChannel))

[e5l]

Ok, let me check. I’ll try to make test interceptor for you :)

[legzo]

Ah ! You're so nice, maybe I just haven't found the good documentation page, but I found it a bit hard to understand how the custom features work (apart from the simple "adding a header" example)

[e5l]

It looks like there is a problem with intercepting content for now. Could you file an issue?

[legzo]

Hi @e5l, I sure could, but I'm not sure what to report... I am able to read the content, is the problem the fact that the proceedWith() fails ?

[e5l]

Nope. It looks like content intercept problem. You have to proceedWith(HttpClientCall(typeInfo, response)) for now. And there is no obvious way to observe the data in the response channel.