Koin: How to inject outside a Fragment or an Activity? (Android Lifecycle Architecture)

[StephaneBg]

Hello,
first of all thanks for the lib. I'm wondering how I can inject outside a Fragment?
For example I'd like to access my Repository instance inside my ViewModel.
Thanks.

[arnaudgiuliani]

Hello StephanBg

If it's not an Android class (Activity, Fragment ...), injection is made by constructor. Be sure to provide a definition in your module and use "get()" to resolve the needed dependency.

Here is an example of how I define my presenter class in the sample-app:
https://github.com/Ekito/koin/blob/master/koin-android/koin-sample-app/src/main/kotlin/koin/sampleapp/di/all_modules.kt#L24

and the presenter class : https://github.com/Ekito/koin/blob/master/koin-android/koin-sample-app/src/main/kotlin/koin/sampleapp/weather/WeatherPresenter.kt

Hope it helps.

[StephaneBg]

Hello Arnaud,
thanks for the quick response but WeatherPresenter is injected inside WeatherActivity which is an Activity.
My ViewModel is created inside a Fragment but with android.arch.lifecycle.ViewModelProviders so I'm not able to inject any object into it. I can use a Factory to pass arguments to the constructor but in the Factory I can't use inject keyword.

[arnaudgiuliani]

You can use "by inject()" in Fragment. But if your app is based on Android Lifecycle Architecture components, Koin needs more extensions to help you :/
If you have a Context or ContextApplication object around, you can use the "getKoin()" accessor, for then inject your component.

Android Lifecycle Architecture components is on the roadmap 👍

[arnaudgiuliani]

A factory provider could also help you (coming in 0.4.0)

[arnaudgiuliani]

Koin version 0.5.0 will bring a module to help you inject into ViewModel. Keep in touch !

[NikolaDespotoski]

@StephaneBg I'm using slightly modified version of ViewModelProviders and I'm injecting the constructor with get(). I was looking also a way to inject properties inside ViewModel.

While you are waiting for 0.5.0. have it here

 context(REPORT) {
            provide { CommentRepositoryImpl() } bind CommentRepository::class
            provide { ReportRepositoryFirestoneImpl() } bind ReportRepository::class

            provide { ReportListFragment() }
            provideFactory {
                val reportRepository: ReportRepository = get()
                val commentRepository: CommentRepository = get()
                val reportFragment : ReportListFragment = get()
                val args = arrayOf(commentRepository, reportRepository)
                val viewModel : ReportViewModel = ViewModelParametrizedProvider.get().of(reportFragment).with(args).get(ReportViewModel::class)
                viewModel
            }
        }

[Baresse]

Hi @StephaneBg
There are several ways to achieve that with the current version 0.5.2

The quick and dirty way will be to add into your ViewModel class :

 val repository = StandAloneContext.koinContext.get<MyRepository>()

The cleaner way will be to write an additional function extension like this in a file named for instance KoinComponentExt.kt :

/**
 * Koin component marker interface
 */
interface KoinComponent

/**
 * inject lazily given dependency
 *
 * @param name - bean name / optional
 */
inline fun <reified T> KoinComponent.inject(name: String = "") = lazy { StandAloneContext.koinContext.get<T>(name) }

Then you just have to make your ViewModel implements the KoinComponent marker interface and that's it. You can now inject from your new marked class.

class YourViewModel : KoinComponent {
   val repository by inject<MyRepository>()
   ...
}

[mohamadk]

val repository = StandAloneContext.koinContext.get<MyRepository>()
not working with 1.0.1
I'm trying to inject okhttp client to AppGlideModule class that's not an activity, fragment class and it cannot be added in the constructor.