Decode gzipped JSON in Akka HTTP

Finally figured this out - this might not be the absolute best to get a bytestring from response but it works .. Turns out you can use Gzip class

and you have two options

1. Gzip.decode
2. Gzip.decoderFlow

Here are my examples in case this helps you:

def getMyDomainObject(resp: HttpResponse):Future[MyDomain] = { for {   byteString <- resp.entity.dataBytes.runFold(ByteString(""))(_ ++ _)   decompressedBytes <- Gzip.decode(byteString)   result <- Unmarshal(decompressedBytes).to[MyDomain]  } yield result}def getMyDomainObjectVersion2(resp:HttpResponse):Future[MyDomain] = {   resp.entity.dataBytes   .via(Gzip.decoderFlow)   .runWith(Sink.head)   .flatMap(Unmarshal(_).to[MyDomain])}

You would expect that compressed content would be managed by akka-http by default, but it only provides PredefinedFromEntityUnmarshallers and inside entity there is not information about Content-encoding header.

To solve this you have to implement your own Unmarshaller and to have it in scope

Example:

implicit val gzipMessageUnmarshaller = Unmarshaller(ec => {      (msg: HttpMessage) => {        val `content-encoding` = msg.getHeader("Content-Encoding")        if (`content-encoding`.isPresent && `content-encoding`.get().value() == "gzip") {          val decompressedResponse = msg.entity.transformDataBytes(Gzip.decoderFlow)          Unmarshal(decompressedResponse).to[String]        } else {          Unmarshal(msg).to[String]        }      }    })