how to make this play scala controller work? - scala

Question

I am trying to create a controller that extracts a file on the fly from an archive and then then renders it as a static asset with the default Asset controller
import play.api.Play.current
// import controllers.Assets
import play.api.Logger
import myextract.Extract
import scala.concurrent.{ExecutionContext, Future}
import play.api.libs.concurrent.Execution.Implicits.defaultContext
object MyAssets extends Controller {
// drop the version and serve the asset
def at(path: String, file: String): Action[AnyContent] = Action.async {
Logger.info("looking for file = %s" format file)
val ret = Future {
Extract.getFile(path, file) // extracts file from an archive
// throws exception if file cannot be extracted
}
ret.map {
v => Assets.at(path, file)
}
}
}
I get these errors at compile
./activator compile
[info] Loading project definition from /home/sylvain/yo-scala/project
[info] Set current project to play-slick-advanced (in build file:/home /sylvain/yo-scala/)
[info] Compiling 1 Scala source and 1 Java source to /home/sylvain/yo-scala/target/scala-2.11/classes...
[error] /home/sylvain/yo-scala/app/controllers/MyAssets.scala:14: overloaded method value async with alternatives:
[error] (block: play.api.mvc.Request[play.api.mvc.AnyContent] => scala.concurrent.Future[play.api.mvc.Result])play.api.mvc.Action[play.api.mvc.AnyContent] <and>
[error] (block: => scala.concurrent.Future[play.api.mvc.Result])play.api.mvc.Action[play.api.mvc.AnyContent]
[error] cannot be applied to (scala.concurrent.Future[play.api.mvc.Action[play.api.mvc.AnyContent]])
[error] def at(path: String, file: String): Action[AnyContent] = Action.async {
[error]
[error] one error found
[error] (compile:compile) Compilation failed

Answer 1

You either have to make sure your action returns a Future:
import play.api.Play.current
// import controllers.Assets
import play.api.Logger
import myextract.Extract
import scala.concurrent.{ExecutionContext, Future}
import play.api.libs.concurrent.Execution.Implicits.defaultContext
object MyAssets extends Controller {
// drop the version and serve the asset
def at(path: String, file: String): Action[AnyContent] = Action.async {
Logger.info("looking for file = %s" format file)
val ret = Future {
Extract.getFile(path, file) // extracts file from an archive
// throws exception if file cannot be extracted
}
ret.map {
v => scala.concurrent.Future {Assets.at(path, file)}
}
}
}
Or change it so it's not async anymore:
import play.api.Play.current
// import controllers.Assets
import play.api.Logger
import myextract.Extract
import scala.concurrent.{ExecutionContext, Future}
import play.api.libs.concurrent.Execution.Implicits.defaultContext
object MyAssets extends Controller {
// drop the version and serve the asset
def at(path: String, file: String): Action[AnyContent] = Action {
Logger.info("looking for file = %s" format file)
val ret = Future {
Extract.getFile(path, file) // extracts file from an archive
// throws exception if file cannot be extracted
}
ret.map {
v => Assets.at(path, file)
}
}
}