CODEWITHSUNDEEP
scalaplayframework
ps0604
ps0604

Reputation: 1081

Returning response from future inside a yield in Play for Scala

In the following code I have a Play for Scala function with a future inside a yield. I get a compilation error type mismatch; found : scala.concurrent.Future[Nothing] required: play.api.mvc.Result. Shouldn't I flatMap the future inside the yield to return the Ok response? 

  def f1 = Future { 1 }
  def f2 = Future { 2 }

  def index = Action.async (parse.json) { request => 

        for { x1 <- f1 }
        yield {
           val f = f2
           f.flatMap { result =>
              Ok("X")
           }

        }
  }

Upvotes: 1

Views: 657

Answers (1)

Matt Fowler
Matt Fowler

Reputation: 2733

No, when you say flatMap you are saying that the result returned in the function is a Future[T], which in your example it returns a Result, so just using a map would work, but is not super idiomatic as you have to flatten as you wind up with a Future[Future[Result]]:

(for { x1 <- f1 } yield {
    val f = f2
    f.map( result =>
       Ok("X")
    )
}).flatten

What is more idiomatic is to use a for comprehension for the whole thing:

for {
  x1 <- f1
  x2 <- f2
} yield {
  Ok("X")
}

Upvotes: 4

Related Questions