Create instance of Dependency Injected class in play 2.5.X

Question

In Play 2.5.X we need to use dependency injection. The following code is an example from play-documentation:

class HomeController @Inject() (configuration: play.api.Configuration) extends Controller {
  def index = Action {
    Ok(views.html.index("Your new application is ready."))
  }
}

If I define some additional helper method getXXX in HomeController and need to access it from somewhere else, how can I access this method?

What I am really interested in is how to create instance of HomeController so that I can use homeControllerInstance.getXXX.

If I try to create instance like following:

val homeControllerInstance = new HomeController()

I get error:

Compilation error[not enough arguments for constructor HomeController: (configuration: play.api.Configuration)HomeController

I tried to change HomeController class declaration to:

class HomeController @Inject(configuration: play.api.Configuration) extends Controller

But this gave me error:

classfile annotation arguments have to be supplied as named arguments

Can someone please explain, how can I fix this?

What is this helper method? Are you sure that controller is the best place to keep it? — michaJlS, Oct 14 '16 at 11:21
Your question is not very clear. Are you asking how to declare the Controller as an injectable component? — jacks, Oct 14 '16 at 11:26
Is this for unit testing ? If this is the case, you might want to check out the guides https://www.playframework.com/documentation/2.5.x/ScalaTestingWithGuice — AME, Oct 14 '16 at 11:28
after you marked you controller with @Inject annotation all parameters will be injected to HomeController and you can then inject HomeController itself whenever you need. — iuriisusuk, Oct 14 '16 at 12:25
@michaJlS: This helper method creates HTTP request and send it to some URL. URL is read from application.conf. — Shailesh, Oct 14 '16 at 12:32
@Nio: No, I am not asking "how to declare the Controller as an injectable component?" — Shailesh, Oct 14 '16 at 12:32
I think you probably want to put this re-useable helper method in a service and then you can inject that in your controllers . In my opinion that would be the most reusable and you can keep your controllers slim/focused on what they do and delegate interaction with some external thing to another component — Barry, Oct 14 '16 at 13:26

score 0 · Answer 1 · answered Oct 20 '16 at 05:01

If you want to use your getXXX method of your class HomeController from Xyz class using google juice, try this

import com.google.inject.Inject

class Xyz @Inject()(homeCon: HomeController) {
   homeCon.getXXX
}

Although I am not sure what your actual problem is, but hope this helps.

score 0 · Answer 2 · answered Nov 15 '16 at 10:58

0

You should instantiate the class with

play.api.Play.current.injector.instanceOf(classOf[UID])

answered Nov 15 '16 at 10:58

searchrome

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score 0 · Answer 3 · answered Mar 08 '18 at 10:02

Sometimes you need to put a new line after the @Inject keyword so this:

class HomeController @Inject(a :IWantThisInjected) (configuration: play.api.Configuration)

fails with that error, but moving the first set of params to the next line can fix it:

class HomeController @Inject (a :IWantThisInjected) (configuration: play.api.Configuration)

Create instance of Dependency Injected class in play 2.5.X

3 Answers3