CODEWITHSUNDEEP
listscalafuture
αƞjiβ
αƞjiβ

Reputation: 3246

Size check on future list in Scala

I have a method which return Future[List[Employee]]. I want to check the list size for various purpose. I am not able to call size on list and I think its because its in Future. Any suggestion?

val employees: Future[List[Employee]] = companyService.findEmployeesWorkingOn(someDate) 
employees match {
  case emp if(emp.size == 1) => Logger.info("Only one employee working")
  case emp if(emp.size == 0) => Logger.info("No one working")
  case _ => Logger.info("Multiple employees working")
}

Upvotes: 3

Views: 1261

Answers (3)

Viktor Klang
Viktor Klang

Reputation: 26579

No need to check the size for your use case:

val employees: Future[List[Employee]] = …
val result = employees map {
  case Nil => "no employees"
  case List(e) => "one employee"
  case es => "multiple employees"
}

Upvotes: 0

elm
elm

Reputation: 20415

Use a for comprehension which desugars to a flatMap,

for ( e <- employees ) yield e.size match {...}

Here list e is matched only if the future succeeds.

Upvotes: 0

Sleiman Jneidi
Sleiman Jneidi

Reputation: 23329

You need to "wait" for the future to happen or not. You can use map to map the Future[List[Employee]] to a Future[Int] and use the onSuccess callback.

val sizeFuture = employees.map(_.size) // returns a Future[Int]
sizeFuture onSuccess {
  case size:Int => println(size) // do your stuff here
}

Upvotes: 3

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