Completing Source[ByteString, _] in Akka-Http

Question

I wanted to use Alpakka for handling S3 upload and download with Akka Steams. However, I got stuck with using Source produced by S3Client within Akka Http routes. The error message I get is:

[error]  found   : akka.stream.scaladsl.Source[akka.util.ByteString,_$1] where type _$1
[error]  required: akka.http.scaladsl.marshalling.ToResponseMarshallable
[error]     complete(source)

I assume that it is some annoying trivial thing, like missing implicit import, but I was not able to pinpoint what I am missing.

I've created some minimal example to illustrate the issue:

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.server.Directives._
import akka.stream.ActorMaterializer
import akka.stream.scaladsl.Source
import akka.util.ByteString

import scala.concurrent.ExecutionContext

class Test {

  implicit val actorSystem: ActorSystem = ActorSystem()
  implicit val materializer: ActorMaterializer = ActorMaterializer()
  implicit val executionContext: ExecutionContext = actorSystem.dispatcher

  val route = (path("test") & get) {
    def source: Source[ByteString, _] = ??? // just assume that I am able to get that value
    complete(source) // here error happens
  }

  Http().bindAndHandle(route, "localhost", 8000)
}

Do you have some suggestions, what can I try? I am using

libraryDependencies += "com.typesafe.akka"%% "akka-http" % "10.0.5"

Completing Source[ByteString, _] in Akka-Http

1 Answers