How can I chain my custom actions when using ActionBuilder - scala

Question

Trying to better understand creating custom actions using action builder.
I have a custom action like:
class LogginInRequest[A](val currentUser: User, request: Request[A]) extends WrappedRequest[A](request)
object ActionWithContext extends ActionBuilder[LogginInRequest] {
def invokeBlock[A](request: Request[A], block: (LogginInRequest[A]) => Future[SimpleResult]) = {
val u = /// load User
block(new LogginInRequest(user, request)
}
}
Could I someone create another custom action like the above that inherits from the above one and builds upon it i.e. chain in the action and access the user object
e.g. Say I now create a new section on my website for admins, so I check the user object in this new action for:
user.isAdmin
If isAdmin is false, then I redirect using the Future.successful(Forbidden) call.
So I would create LoggedInAdmin based on LogginInRequest but simply checking for the property isAdmin (this is just an example but I want to know if I can do this).
Is it possible to pass an argument to my custom action that I created using action builder so I can do this?
def someAction(...):= MyCustomActionBuilder(userService) {
// ...
}
i.e. I am passing in a argument to it.

Answer 1

With Play 2.3, action composition using ActionBuilder got a whole lot better. The example below shows how you can define a standard ActionBuilder that creates a wrapped request, and then chain that builder together with an ActionTransformer to create a new wrapped request.
import scala.concurrent.Future
import org.scalatest.{MustMatchers, WordSpec}
import play.api.mvc._
import play.api.test.FakeRequest
import play.api.test.Helpers._
class ChainingTest extends WordSpec with MustMatchers {
class WrappedReq1[A](val str: String, request: Request[A]) extends WrappedRequest[A](request)
object ActionWithReq1 extends ActionBuilder[WrappedReq1] {
def invokeBlock[A](request: Request[A], block: (WrappedReq1[A]) => Future[Result]) = {
block(new WrappedReq1(request.headers("1"), request))
}
}
class WrappedReq2[A](val str1: String, val str2: String, request: Request[A]) extends WrappedRequest[A](request)
val ActionWithReq2 = ActionWithReq1 andThen new ActionTransformer[WrappedReq1, WrappedReq2] {
override protected def transform[A](request: WrappedReq1[A]): Future[WrappedReq2[A]] = {
Future.successful(new WrappedReq2[A](request.str, request.headers("2"), request))
}
}
"chained actions" should {
"work" in {
val request = FakeRequest().withHeaders("1" -> "one", "2" -> "two")
val response = ActionWithReq2 { r => Results.Ok(r.str1 + "-" + r.str2) }(request)
contentAsString(response) must equal("one-two")
}
}
}
There is an ActionTransformer trait for modifying your request wrapper, and an ActionFilter for intercepting certain requests and immediately returning a result.
ScalaActionsComposition describes the traits in more detail.