Koin: Koin in SDK - by viewModel() doesn't work with custom context

[pawelmarchewka]

Hi.

I use Koin (version 2.0.0-beta-1) in my Android application, and it works great 🙂

Now I am creating an SDK from parts of that application, so I intend to use custom context as described in Koin context isolation

I have an object to store Koin instance

object TcKoinContext {
    lateinit var koin: Koin

    @Synchronized
    fun init(context: Context) {
        val koinApp = koinApplication {
            androidContext(context)
            modules(KoinModules.all)
        }
        koin = koinApp.koin
    }
} 

and interface

interface TcKoinComponent : KoinComponent {
    override fun getKoin(): Koin = TcKoinContext.koin
}

which I implement in my Application class, activity, fragments and other places where I need to inject dependencies.

Although I thought I done everything correctly, after running the app, I immediately got java.lang.IllegalStateException: KoinApplication has not been started

I investigated it and noticed that
fun ComponentCallbacks.getKoin(): Koin = GlobalContext.get().koin
is always using global context and because Application, Activity, Fragment, etc. implements ComponentCallbacks it never uses my instance of Koin from implemented TcKoinComponent.

So I changed imports from org.koin.android.ext.android.inject to org.koin.core.inject and it helped because this version fo inject is using KoinComponent.getKoin() and not ComponentCallbacks.getKoin()

Now I have a problem with by viewModel()

java.lang.IllegalStateException: KoinApplication has not been started
        at org.koin.core.context.GlobalContext.get(GlobalContext.kt:37)
        at org.koin.core.KoinComponent$DefaultImpls.getKoin(KoinComponent.kt:32)
        at org.koin.androidx.viewmodel.ViewModelResolutionKt$makeViewModelProvider$1.getKoin(ViewModelResolution.kt:42)
        at org.koin.androidx.viewmodel.ViewModelResolutionKt$makeViewModelProvider$1.create(ViewModelResolution.kt:44)
        at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:135)
        at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:103)
        at org.koin.androidx.viewmodel.ViewModelResolutionKt.getInstance(ViewModelResolution.kt:22)
        at org.koin.androidx.viewmodel.ViewModelResolutionKt.resolveViewModelInstance(ViewModelResolution.kt:16)

I think there is a bug in makeViewModelProvider function:

private fun <T : ViewModel> makeViewModelProvider(
    vmStore: ViewModelStore,
    parameters: ViewModelParameters<T>
): ViewModelProvider {
    return ViewModelProvider(
        vmStore,
        object : ViewModelProvider.Factory, KoinComponent {
            override fun <T : ViewModel> create(modelClass: Class<T>): T {
                return getKoin().get(parameters.clazz, parameters.name, null, parameters.parameters)
            }
        })
}

It creates anonymous object which implements KoinComponent with default implementaion of getKoin() method which uses Global context and that it is source of this crash. I think it should use activity/fragment (implementing custom KoinComponent) as source of Koin instance.

So instead of object implementing KoinComponent, method create should probalby use fun LifecycleOwner.getKoin() = (this as ComponentCallbacks).getKoin(). But is uses getKoin() from ComponentCallbacks and not from KoinComponent so it won't work with custom context from my TcKoinComponent anyway 🙁

I hope it will be helpful 🙂

Besides the problem with makeViewModelProvider method, it would be great if fun ComponentCallbacks.getKoin() could use KoinComponent.getKoin() so the same org.koin.android.ext.android.inject extension method can be used with Global and custom context.

[arnaudgiuliani]

remind me this proposal: https://github.com/InsertKoinIO/koin/pull/341

[arnaudgiuliani]

Yeah context isolation is not enough on this viewmodel side.

For Android globally, you should rewrite a custom KoinComponent to resuse get/inject with your instance and avoid using the API that uses Global context

[pawelmarchewka]

For Android globally, you should rewrite a custom KoinComponent to resuse get/inject with your instance and avoid using the API that uses Global context

Can you explain what do you mean by that because I thought that implementing custom KoinComponent interface in activities, fragments, etc. will be enough to use custom context on Android? (and it works that way although, as I wrote in my first comment, you have to remember to use core version of get/inject extension methods which is a bit confusing).

[arnaudgiuliani]

@pawelmarchewka check the last version of Koin( has been fixed in beta-3). We better handle Custom KoinComponent & custom Koin instances. You can use directly TcKoinComponent

An example here: https://github.com/InsertKoinIO/koin/blob/master/koin-projects/examples/android-samples/src/main/java/org/koin/sample/android/components/sdk/SDKActivity.kt

[pawelmarchewka]

@arnaudgiuliani It works, thanks! 🙂

[EhsanMashhadi]

@arnaudgiuliani It works. I think you should add this to the documentation too!