Agfdhyk

I have a next root component:

@Singleton

@Component(modules = [AndroidInjectionModule::class,

        AndroidSupportInjectionModule::class, 

        ActivityBuilderModule::class])

interface RootComponent : AndroidInjector<DaggerApplication> {

    fun inject(myApplication: MyApplication)

    override fun inject(photoPartyApplication: DaggerApplication)



    @Component.Builder

    interface Builder {

        @BindsInstance

        fun application(application: Application): Builder

        fun build(): RootComponent

    }

}

In ActivityBuilderModule:

@Module

abstract class ActivityBuilderModule {



    @ContributesAndroidInjector(modules = [MainActivityModule::class,

            ViewModelModule::class])

    @ActivityScope

    abstract fun bindMainActivity(): MainActivity



    @ContributesAndroidInjector(modules = [SecondaryActivityModule::class,

            ViewModelModule::class,

            FragmentBuilderModule::class])

    @ActivityScope

    abstract fun bindSecondaryActivity(): SecondaryActivity



}

ViewModelModule is a trivial module to help making constructor injections in ViewModel classes and consists of @Binds between specific instances and ViewModel type.

MainActivityModule and SecondaryActivityModule define specific dependencies for corresponding activities.

The key thing is that when I added this FragmentBuilderModule - compilation started to emit errors. The stack trace is the next:

error: [Dagger/MissingBinding] some_package.SpecificDependency cannot be provided without an @Inject constructor or an @Provides-annotated method.

public abstract interface RootComponent extends dagger.android.AndroidInjector {

^

A binding with matching key exists in component: some_package.ActivityBuilderModule_BindMainActivity.MainActivitySubcomponent

some_package.SpecificDependency is injected at some_package.MainViewModel(specificDependency, …)

some_package.MainViewModel is injected at some_package.ViewModelModule.mainViewModel(viewModel)

Map<Class<? extends ViewModel>, Provider<ViewModel>> is injected at

      some_package.ViewModelFactory(viewModelProviders)

some_package.ViewModelFactory is injected at some_package.ViewModelModule.bindViewModelFactory(factory)

android.arch.lifecycle.ViewModelProvider.Factory is injected at some_package.MyFragment.viewModelFactory

some_package.MyFragment is injected at dagger.android.AndroidInjector.inject(T)

[some_package.RootComponent → some_package.ActivityBuilderModule_BindSecondaryActivity.SecondaryActivitySubcomponent → some_package.FragmentBuilderModule_ProvideMyFragmentFactoryMyFragmentSubcomponent]

As far as I can understand, Dagger assumes that the whole dependencies graph has to be properly constructed for the map of Class<? extends ViewModel> -> Provider<ViewModel>, and if some ViewModels fall into factory, and that factory is injected into a component, then if component will ask for any viewmodel, it has to be delivered. And in order to deliver all the viewmodels, again, all the dependencies have to be available (what's not true, because specific dependency for the MainViewModel is available only from MainModule, and that's what dagger says before the stack trace).

Is there a workaround to provide dependencies to the map of Class<? extends ViewModel> -> Provider<ViewModel> on demand instead of building the whole graph at compile time (which is leading to the compile-time error)

First add ViewModelModule at RootComponent

 @Singleton

 @Component(modules = [AndroidInjectionModule::class,

            AndroidSupportInjectionModule::class, 

            ActivityBuilderModule::class,

            ViewModelModule::class])                 // add this so you don't have to add for every activity

    interface RootComponent : AndroidInjector<DaggerApplication> {

        fun inject(myApplication: MyApplication)

        override fun inject(photoPartyApplication: DaggerApplication)



        @Component.Builder

        interface Builder {

            @BindsInstance

            fun application(application: Application): Builder

            fun build(): RootComponent

        }

    }

Now in ActivityBuilderModule add only activty

 @Module

 abstract class ActivityBuilderModule {



    @ContributesAndroidInjector

    @ActivityScope

    abstract fun bindMainActivity(): MainActivity

 }

Now In ViewModelModule add all ViewModel

 @Module

 abstract class ViewModelModule {



    @Binds

    @IntoMap

    @ViewModelKey(MainActivityModule::class)

    abstract fun bindMainActivityViewModel(mainActivityViewModel: MainActivityModule): ViewModel

}

Add ViewModelKey

 @MustBeDocumented

 @kotlin.annotation.Target(AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY_GETTER, AnnotationTarget.PROPERTY_SETTER)

 @kotlin.annotation.Retention(AnnotationRetention.RUNTIME)

 @MapKey

 internal annotation class ViewModelKey(val value: KClass<out ViewModel>)

And ViewModelFactory

@Singleton

class KotlinViewModelFactory @Inject

constructor(private val creators: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>) : ViewModelProvider.Factory {



    @Suppress("UNCHECKED_CAST")

    override fun <T : ViewModel> create(modelClass: Class<T>): T {

        var creator: Provider<out ViewModel>? = creators[modelClass]

        if (creator == null) {

            for ((key, value) in creators) {

                if (modelClass.isAssignableFrom(key)) {

                    creator = value

                    break

                }

            }

        }

        if (creator == null) {

            throw IllegalArgumentException("unknown model class $modelClass")

        }

        try {

            Timber.d(creator.toString())

            return creator.get() as T

        } catch (e: Exception) {

            throw RuntimeException(e)

        }

    }

}