Play framework 2.3 ActionBuilder composition issue

Question

I really like play framework 2.3's ActionBuilder and the andThen method that allows you to dynamically compose actions.

Here's a snippet of how I want to use action composition:

def showHomepage = RedirectingAction andThen
    AuthenticatedAction andThen NotificationAction async { request =>
      Future {
        Ok(views.html.homepage.render(request.user, request.notifications ))
     }
 }

As you can guess, NotificationAction depends on AuthenticatedAction, and hence needs AuthenticatedRequest which contains the User object.

The code complains on:

object NotificationAction extends ActionBuilder[NotificationAuthRequest] {
    def invokeBlock[A](request: AuthenticatedRequest[A], block: (NotificationAuthRequest[A]) => Future[Result]) = { ...

The error is: object creation impossible, since method invokeBlock in trait ActionFunction of type [A](request: play.api.mvc.Request[A], block: controllers.v3.ScalaHomepageController.NotificationAuthRequest[A] => scala.concurrent.Future[play.api.mvc.Result])scala.concurrent.Future[play.api.mvc.Result] is not defined

Apparently it allows only:

def invokeBlock[A](request: Request[A], block: ...

but not:

def invokeBlock[A](request: AuthenticatedRequest[A], block: ...

I'd really appreciate if someone could throw light on this. Maybe my approach is wrong, but I don't like the idea of precomposed actions (like using ActionFunction) because I could have more actions that I could be mixing in at a later point.

Here's the code:

case class AuthenticatedRequest[A](val user: Option[User], request: Request[A]) extends  WrappedRequest(request)

case class NotificationAuthRequest[A](val user: Option[User], val notifications: Option[List[UserNotificationData]], request: Request[A]) extends  WrappedRequest(request)


  object RedirectingAction extends ActionBuilder[Request] {

      def invokeBlock[A](request: Request[A], block: (Request[A]) => Future[Result]) = {
          Future {
            Redirect(REDIRECT_URL + request.uri + paramString)
          }
      }
  }

  object AuthenticatedAction extends ActionBuilder[AuthenticatedRequest] {

    def invokeBlock[A](request: Request[A], block: (AuthenticatedRequest[A]) => Future[Result]) = {
      request.cookies.get("uid") map {
        cookie =>
          val user = userClient.getUserById(userId(cookie)).get
          block(AuthenticatedRequest[A](user, request))
      } getOrElse {
        block(AuthenticatedRequest[A](userClient.getUserById(uid).get, request))
      }
    }


    def userId(cookie: Cookie) = {
      if(AppUtil.isProd) cookie.value else IMPERSONATE_ID.getOrElse(cookie.value)
    }
  }

  object NotificationAction extends ActionBuilder[NotificationAuthRequest] {
    def invokeBlock[A](request: AuthenticatedRequest[A], block: (NotificationAuthRequest[A]) => Future[Result]) = {
      request.user.map {
        user => block(NotificationAuthRequest[A](Some(user), userClient.getNotifications(user.getId).get.map(_.toList), request))
      }.getOrElse {
        block(NotificationAuthRequest[A](None, None, request))
      }
    }
  }

bjoernhaeuser bjoernhaeuser · Accepted Answer · 2015-01-22T09:47:16

Reading the docs I think you need to have ActionRefiners and ActionTransformers.

This is what I came up with:

package controllers

import play.api.mvc._

import scala.concurrent.Future

case class User(id: Long)

case class UserNotificationData(text: String)

case class AuthRequest[A](user: Option[User], request: Request[A]) extends WrappedRequest(request)

case class AuthNotificationRequest[A](user: Option[User], notifications: Option[List[UserNotificationData]], request: Request[A]) extends WrappedRequest(request)

object RedirectingAction extends ActionBuilder[Request] {

  def invokeBlock[A](request: Request[A], block: (Request[A]) => Future[Result]) = {
    block(request)
  }
}

object AuthenticatedAction extends ActionBuilder[AuthRequest] with ActionTransformer[Request, AuthRequest] {

  def transform[A](request: Request[A]) = Future.successful {
    request.cookies.get("uid") map {
      cookie =>
        val user = Some(User(1))
        AuthRequest[A](user, request)
    } getOrElse {
      AuthRequest[A](Some(User(1)), request)
    }
  }
}

object WithNotifications extends ActionTransformer[AuthRequest, AuthNotificationRequest] {
  def transform[A](request: AuthRequest[A]) = Future.successful {
    request.user.map { user => AuthNotificationRequest[A](Some(user), Some(List(UserNotificationData("Notification"))), request)} getOrElse {
      AuthNotificationRequest[A](None, None, request)
    }
  }
}

object Application extends Controller {

  def index = (RedirectingAction andThen AuthenticatedAction andThen WithNotifications) { request: AuthNotificationRequest[AnyContent] =>
    Ok(views.html.index("Your new application is ready."))
  }

}

Play framework 2.3 ActionBuilder composition issue

1 Answers