I have defined a custom ToEntityMarshaller for type User. When requesting
/users it returns an empty JSON array. Only when I remove the implicit def
userMarshaller it return the correct representation of the stream.
Anybody has a pointer on what is going wrong?
import akka.NotUsed
import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.common.{EntityStreamingSupport,
JsonEntityStreamingSupport}
import akka.http.scaladsl.model.{HttpEntity, StatusCodes, _}
import akka.http.scaladsl.server.Directives._
import akka.stream.ActorMaterializer
import akka.http.scaladsl.marshallers.sprayjson.SprayJsonSupport._
import akka.http.scaladsl.marshalling.{Marshaller, ToEntityMarshaller,
ToResponseMarshaller}
import akka.http.scaladsl.model.TransferEncodings.gzip
import akka.http.scaladsl.model.headers.{HttpEncoding, HttpEncodings}
import akka.http.scaladsl.model.ws.{Message, TextMessage}
import akka.stream.scaladsl.{Flow, Source}
import akka.util.ByteString
import spray.json.DefaultJsonProtocol
import spray.json.DefaultJsonProtocol._
import scala.concurrent.Future
import scala.io.StdIn
import scala.util.Random
final case class User(name: String, id: String)
trait UserProtocol extends DefaultJsonProtocol {
import spray.json._
implicit val userFormat = jsonFormat2(User)
val `vnd.example.api.v1+json` =
MediaType.applicationWithFixedCharset("vnd.example.api.v1+json",
HttpCharsets.`UTF-8`)
implicit def userMarshaller: ToEntityMarshaller[User] = Marshaller.oneOf(
Marshaller.withFixedContentType(`vnd.example.api.v1+json`) { organisation =>
HttpEntity(`vnd.example.api.v1+json`, organisation.toJson.compactPrint)
})
}
object ApiServer extends App with UserProtocol {
implicit val system = ActorSystem("api")
implicit val materializer = ActorMaterializer()
implicit val executionContext = system.dispatcher
implicit val jsonStreamingSupport: JsonEntityStreamingSupport =
EntityStreamingSupport.json()
.withParallelMarshalling(parallelism = 10, unordered = false)
// (fake) async database query api
def dummyUser(id: String) = User(s"User $id", id.toString)
def fetchUsers(): Source[User, NotUsed] = Source.fromIterator(() =>
Iterator.fill(10000) {
val id = Random.nextInt()
dummyUser(id.toString)
})
val route =
pathPrefix("users") {
get {
complete(fetchUsers())
}
}
val bindingFuture = Http().bindAndHandle(route, "localhost", 8080)
println(s"Server online at http://localhost:8080/\nPress RETURN to stop...")
StdIn.readLine()
bindingFuture.flatMap(_.unbind()).onComplete(_ => system.terminate())
}
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