Dependency Injection
If you’d like to introduce dependency injection pattern in Skinny apps, we recommend using Scaldi which is a pretty cool library to inject deps.
An optional module skinny-scaldi is an easy-to-use Scaldi adaptor module which is developed by Skinny Framework team.
See also the following blog article and example:
http://blog.seratch.net/post/90627493988/scaldi-dependency-injection-in-skinny-apps
https://github.com/skinny-framework/skinny-scaldi-example/
Don’t use in Scala 2.10.x
This is an important notice.
Due to SI-6240, Scaldi doesn’t work fine in Scala 2.10.x.
https://github.com/scaldi/scaldi/issues/16
Use Scala 2.11 (or higher).
Setup
skinny-scaldi is an optional module (= not to be enabled by default). Add it to your libraryDependencies.
libraryDependencies += "org.skinny-framework" %% "skinny-scaldi" % "4.0.0"
Simple Usage
A module which injects services
This is a simple module which injects service objects to controllers or else.
package service
trait EchoService {
def echo(msg: String): String
}
class EchoServiceImpl extends EchoService {
override def echo(msg: String) = msg
}
package module
class ServicesModule extends scaldi.Module {
bind[EchoService] to new EchoServiceImpl
}
Yet another module
The following is another module example.
package model
case class AppName(value: String)
package module
class AppModule extends scaldi.Module {
bind[AppName] to AppName("My First Skinny App")
}
Integrating Scaldi modules to Skinny controllers
skinny-scaldi‘s Scaldi integration is pretty simple. Just prepare configuration and add ScaldiFeature trait to controllers.
And add modules to src/main/resources/application.conf like this.
Be aware that module in application.conf should be not an object but a class.
development {
scaldi {
modules: ["module.ServicesModule", "module.AppModule"]
}
}
test {
scaldi {
modules: ["module.ServicesModule", "module.AppModule"]
}
}
The following is the base controller.
import skinny._
import skinny.controller.feature.ScaldiFeature
trait ApplicationController extends SkinnyController
with ScaldiFeature {
}
If you’d like to replace modules after loading from application.conf, just override scaldiModules: Seq[scaldi.Module].
package model
case class Locale(value: String)
object LocaleModule extends scaldi.Module {
bind[Locale] to new Locale("ja")
}
package controller
trait ApplicationController extends SkinnyController
with ScaldiFeature {
// this modules will be used instead of loaded one from application.conf
// you can use singleton objects
override def scaldiModules = Seq(new ServicesModule, LocaleModule)
}
Using Scaldi APIs
Now you can use Scaldi APIs like inject[A].
class InjectedController extends ApplicationController {
def index = {
val service: EchoService = inject[EchoService]
service.echo(params.getAs[String]("echo").getOrElse(""))
}
def appName = inject[AppName].value // "My First Skinny App"
// SkinnyEnv and SkinnyConfig are available by default
// though you can do the same thing by using companion objects
def env = inject[SkinnyEnv].getOrElse("xxx") // "development"
}