play-json-找不到参数um的隐式值

Question

I know this question has been asked many times before, however all of them use spray-json. I wanted to use play-json. This might be why the proposed solutions don't solve the problem. The trait with the route is in a separate file named RestApi.scala . The Http.bindAndHandle which makes use of it is in the file named Main.scala . Both files without irrelevant element removed are presented below. If you want to see the whole file please click at the links above.

RestApi.scala

package restApi

import akka.actor.{ActorSystem, Props}
import akka.http.scaladsl.model.StatusCodes
import akka.http.scaladsl.server.Directives._
import akka.pattern.ask
import akka.stream.ActorMaterializer
import akka.util.Timeout

import scala.concurrent.ExecutionContext
import scala.concurrent.duration._

trait RestApi {
  import models._
  import cassandraDB.{WriterActor, ReaderActor}
  implicit val system: ActorSystem
  implicit val materializer: ActorMaterializer
  implicit val ec: ExecutionContext

  implicit val timeout = Timeout(20 seconds)

  val cassandraWriterWorker = system.actorOf(Props[WriterActor], "cassandra-writer-actor")
  val cassandraReaderWorker = system.actorOf(Props[ReaderActor], "cassandra-reader-actor")

  val route =
    pathPrefix("api") {
      pathSuffix("contact") {
        // the line below has the error
        (post & entity(as[Contact])) { contact =>
          complete {
            cassandraWriterWorker ! contact
            StatusCodes.OK
          }
        }
      } ~
      pathSuffix("gps"/ "log") {
        // an analogous error message is shown in the line below
        (post & entity(as[GpsLog])) { gpsLog =>
          complete {
            cassandraWriterWorker ! gpsLog
            StatusCodes.OK
          }
        }
      }
    }
}

Main.scala

package initialization

import akka.actor.{ActorSystem, Props}
import akka.http.scaladsl.Http
import akka.stream.ActorMaterializer
import cassandraDB.{ConfigCassandraCluster, ReaderActor, WriterActor}
import gcm.GcmServer
import restApi.RestApi

object Main extends App with ConfigCassandraCluster with RestApi {

  override implicit val system = ActorSystem()
  override implicit val materializer = ActorMaterializer()
  override implicit val ec = system.dispatcher

  val write = system.actorOf(Props(new WriterActor(cluster)))
  val read = system.actorOf(Props(new ReaderActor(cluster)))
  val gcmServer = system.actorOf(Props(new GcmServer(11054...,"AIzaSyCOnVK...")), "gcm-server")
  val bindingFuture = Http().bindAndHandle(route, "localhost", 8080)


}

I point out the line where the error occurs in RestApi.scala Error Message:

Error:(31, 26) could not find implicit value for parameter um: akka.http.scaladsl.unmarshalling.FromRequestUnmarshaller[models.Contact]
        (post & entity(as[Contact])) { contact =>
                         ^

The Contact is a data model defined in Contact.scala .

I hope this isn't a duplicate, but I really don't think so. Any help is much appreciated.

Answer 1

It turns out there is an easy solution. Simply add resolvers += Resolver.bintrayRepo("hseeberger", "maven") to your build file and then "de.heikoseeberger" %% "akka-http-play-json" % "1.5.3" to your libraryDependencies and import import de.heikoseeberger.akkahttpplayjson.PlayJsonSupport._ into your code. You can now use play-json like you would use spray-json.