Managed controllers in Play 2.3 with DI (Scaladi / Guice)

Question

thank you in advance for taking the time to take a look at my current problem with play.

I am still trying out the Playframework, currently in version 2.3.

At the moment I try to figure dependency injection out. I followed the tutorials provided in the activator for guice as well as scaladi and always resulting in the same compiler error:

play.PlayExceptions$CompilationException: Compilation error[object Application is not a member of package controllers Note: class Application exists, but it has no companion object.]

This makes me think I am missing a more universal part of the Playframework because the problem is not tied to a specific DI framework.

So let me describe what I tried with scaladi (any working solution with guice would also be appreciated):

defining the route in conf/routes:

GET     /        @controllers.Application.index

(added the @ for support of managed controllers which is supported since play 2.1 afaik)

defining the controller:

package controllers

import scaldi.{Injector, Injectable}
import scala._
import play.api._
import play.api.mvc._
import services.GreetingService

class Application(implicit inj: Injector) extends Controller with Injectable {
  val greetService= inject [GreetingService]

  def index = Action {
    Ok("Here I am")
  }
}

defining the Global for modifing the GlobalSetting under app\Global.scala:

import modules.ApplicationModule
import play.api.GlobalSettings
import scaldi.play.ScaldiSupport

object Global extends GlobalSettings with ScaldiSupport {

  def applicationModule = new ApplicationModule
}

and finally the application module under app\modules\ApplicationModule.scala:

package modules

import controllers.Application
import scaldi.Module

class ApplicationModule extends Module {
  binding to new Application
}

So I really would appreciate any help to figure out why Application class could not be located within the package controllers. Also again I would be happy about any working solution may it be guice or scaladi.

Thank you!

Edit: The problem was a second controller for a different route that was also registered under "/conf/routes/". This controller was not yet manged. So after I adapted the steps I described above to the second Controller everything worked fine.

Answer 1

So it seems the mistake was to have another route configured which was not managed. This caused the object Application is not a member of package controllers Note: class Application exists, but it has no companion object. error.

Because my other controller (User) was indeed an object and not a class. So transfering the UserController to class and scaldi fixed this issue. The transfer of the controller was identical to the Applicationcontroller i described above.

Answer 2

Controller instances (declared in a routing using the @ notation) are initialised using a method in Global:

def getControllerInstance[A](controllerClass: Class[A]): A

So if you want to plug-in a DI framework, you need to override this method to turn a Class[A] into an instance of A.

Answer 3

In my case, I solved by adding the following to build.sbt:

routesGenerator := InjectedRoutesGenerator