CODEWITHSUNDEEP
scalafuture
curiousengineer
curiousengineer

Reputation: 2607

Exception handling with Scala Future failed scenario

I have the following test method

def test() = {
val aa = Future{10} map {
  case x if x%2 == 0 => (x,x)
  case _ => val kk = Future.failed(BadRequestException("dd")); kk
 }
 aa
}

If I remove the case _ then the return type of method is Future[(Int, Int)] which is exactly what I want. However, when I add the case _ scenario the return type becomes Future[Object]. I am not able to understand what should I change as other similar methods in our code base do similar things(I am sure I am missing something subtle) and the return type remains of the nature Future[(Int, Int)]. Afterall, when I am throwing an exception for a scenario, I would not want the return type of the method to be changed. What am I missing or doing wrong?

Upvotes: 1

Views: 466

Answers (1)

rogue-one
rogue-one

Reputation: 11587

you should use flatMap instead of map as shown below. with map method the return type of case _ is Future[BadRequestException] and for case x if x%2 == 0 the return type is (Int, Int). This is leading you to have a net return type of Future[Object]. This can be corrected by using the flatMap instead of map as shown below.

def test() = Future{10} flatMap {
  case x if x%2 == 0 => Future.successful((x,x))
  case _ => Future.failed(BadRequestException("dd"))
 }

Upvotes: 3

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