Example usage of GlobalSettings#onRouteRequest in Play framework 2.0.x scala

play20-scala-add-http-response-header.scala

import play.api._
import mvc._

import controllers.Info.VERSION_PROPERTY
import controllers.Info.DEFAULT_VERSION

object Global extends GlobalSettings {
  val VERSION_PROPERTY = "my.property.name"
  val DEFAULT_VERSION = "0.0.0"

  def WithAppVersionHeader[A](action: Action[A]): Action[A] = {
    Action(action.parser) { request =>
      val result = action(request)
      result match {
        case r: PlainResult => r.withHeaders(VERSION_PROPERTY -> System.getProperty(VERSION_PROPERTY, DEFAULT_VERSION))
        case _ => result
      }
    }
  }

  override def onRouteRequest(request: RequestHeader): Option[Handler] = {
    super.onRouteRequest(request).map { handler =>
      handler match {
        case a: Action[_] => WithAppVersionHeader(a)
        case _ => handler
      }
    }
  }

}