Return Future Message from an Actor

Question

I have an existing `API` which returns a `Future`. Now introducing an `Actor` for one of the use cases and trying to continue using same service `API` from it. From below you can see `MyService.saveValues` return future. ``` object MyActor { implicit val ec = scala.concurrent.ExecutionContext.Implicits.global implicit val timeout = Timeout(1 second) case class SampleMessage(list: List[String]) val actorSystem = //get actorSystem that was created at the startup def saveMessage(list: List[String]) ={ val res = (actorSystem.actorOf(Props[MyActor]) ? SaveMyMessage(list) ).mapTo[Future[\/[Throwable,String]] //res map{ r=> //} } } class MyActor extends Actor { import MyActor._ def receive = { case SaveMyMessage(list) => val originalSender = sender val res : Future[\/[Throwable,String] ] = MyService.saveValues(list) originalSender ! res } } ``` As you can see in `def saveMessage` I am using `ask` to wait for a result from an actor. However `ask` also creates its own future so result (`val re…

Accepted Answer

`pipeTo` forwards the result of a Future to an `ActorRef`.

```
import akka.pattern.pipe

val originalSender = sender
val res : Future[\/[Throwable,String] ] = MyService.saveValues(list)
res pipeTo originalSender
```

If `saveValues` throws, your future never complete and will end up timing something out though.

If you ever end up with `Future[Future[A]]`, but want `Future[A]` as a result of `sequencing/traversing` or something, you can always "flatMap that shit."

```
import ExecutionContext.Implicits.global
val foo: Future[Future[Int]] = ???
val bar: Future[Int] = foo.flatMap(identity)
```

If you already depend on scalaz (and scalaz.contrib if on scalaz 7.0.x), you can use `join` defined in monad syntax.

```
import scalaz.syntax.monad._
import scalaz.contrib.std.scalaFuture._
val bar2: Future[Int] = foo.join
```

Return Future Message from an Actor

Solution

Problem