jerome jerome - 4 months ago 22
Scala Question

Scala play Guice injection

I'm using scala play 2.5 and I have the following error while trying to inject an object in one of my controllers.
I'm using the default injection framework given with play which is Guice.

ProvisionException: Unable to provision, see the following errors:
1) No implementation for services.MyService was bound.
while locating services.MyService for parameter 0 at controllers.MyController.<init>(MyController.scala:12)
while locating controllers.MyController for parameter 3 at router.Routes.<init>(Routes.scala:55)
while locating router.Routes
while locating play.api.inject.RoutesProvider while locating play.api.routing.Router for parameter 0 at play.api.http.JavaCompatibleHttpRequestHandler.<init>(HttpRequestHandler.scala:200)
while locating play.api.http.JavaCompatibleHttpRequestHandler
while locating play.api.http.HttpRequestHandler for parameter 4 at play.api.DefaultApplication.<init>(Application.scala:221) at play.api.DefaultApplication.class(Application.scala:221)
while locating play.api.DefaultApplication
while locating play.api.Application


Here is the controller:

package controllers

import services.MyService

class MyController @Inject()(myService: MyService, val messagesApi: MessagesApi) extends Controller with I18nSupport {

def someFunctionThatUsesMyService(url: String) = Action {}
}


Here is the service I would like to inject:

package services

import javax.inject._

trait MyService {
def op(param1: String, param2: String): Boolean
}

@Singleton
class BasicMyService extends MyService {
override def op(param1: String, param2: String): Boolean = true
}


That is how I'm using it:

@Singleton
class HomeController @Inject() extends Controller {

/**
* Create an Action to render an HTML page with a welcome message.
* The configuration in the `routes` file means that this method
* will be called when the application receives a `GET` request with
* a path of `/`.
*/
def index = Action {
//Ok(views.html.index("Your new application is ready."))
Redirect(routes.MyController.someFunctionThatUsesMyService(Some(routes.OtherController.welcomePage().url)))
}

}

Answer Source

You should add ImplementedBy annotation to Service trait

package services

import javax.inject._

@ImplementedBy(classOf[BasicMyService])
trait MyService {
    def op(param1: String, param2: String): Boolean
}

@Singleton
class BasicMyService extends MyService {
    override def op(param1: String, param2: String): Boolean = true
}