rendering a page after Future is done with Play2 - scala

Question

Using Play2 framework with Slick DB manager, I have a class that encapsulates DB access, and a controller in charge of returning that information to the user. There are roughly like this:
Class with DB access:
override def getAllAnswersFuture(userID: Int): Future[List[UserAnswer]] = {
(DB QUERY CREATION AS allAnswersQuery)
val myquery : Future[Seq[(Int, String)]] =myDB.run(allAnswersQuery.result)
myquery.map{x => x.map(elem =>(
UserAnswer(elem._1, elem._2).toList}
}
Controller:
def index = Action { request =>
request.session.get("userID").map { userID =>
val myUser = userStorage.getUser(userID.toInt)
val allAnswersFuture = questionStorage.getAllAnswersFuture(myUser.id)
allAnswersFuture onComplete {case _ => Ok(views.html.app.stats())}
Ok(views.html.app.index("Future did not work"))
}.getOrElse {
Unauthorized("Oops, you are not connected")
}
}
For some reason, the content of onComplete is never shown, returning the "future did not work" instead.
My question is, How do I tell Play2 to wait until the DB query has been completed and then print the results?

Answer 1

Use Action.async for dealing with futures and try doing something like:
def index = Action.async { request =>
allAnswersFuture.map{_ => Ok(views.html.app.stats())}.recover {
case ex: Exception =>
Ok(views.html.app.index("Future did not work"))
}
}
Instead of using onComplete on future use Map and recover, If you want to return anything on future callback. OnComplete on Future won't return anything, Its return type is Unit.
In case of Future success, your stats page will be populated and in failure index page will be populated from recover block.
And in your getOrElse block use:
Future.successful(Unauthorized("Oops, you are not connected"))
This will do the needful