Dagger 2 - IncompatiblyScopedBindings

Question

I’m trying to create an basic architecture with Dagger 2 for my study project but I have encountered several problems with it…

The current error daggers tell me

FeedMeApplicationComponent.java:7: error: [Dagger/IncompatiblyScopedBindings] .FeedMeApplicationComponent (unscoped) may not reference scoped bindings:

I only have this problem when I add the ActivityMainModule as a module of the application

and ActivityMainModule contains a sub component only related to the MainActivity.

I don’t understand why I cannot add this module of sub component to the Application Graph :confusing

Those are my Dagger classes…

class FeedMeApplication : DaggerApplication() {

    override fun applicationInjector(): AndroidInjector<out DaggerApplication> {
        return DaggerFeedMeApplicationComponent.factory().create(this)
    }
}

@Component(modules = [AndroidInjectionModule::class, NetworkModule::class, NutritionModule::class, ActivityMainModule::class])
interface FeedMeApplicationComponent : AndroidInjector<FeedMeApplication> {

    @Component.Factory
    interface Factory {
        fun create(@BindsInstance context: Context): FeedMeApplicationComponent
    }

    override fun inject(instance: FeedMeApplication?)
}

@Module
object NetworkModule {

    @Singleton
    @Provides
    @JvmStatic
    fun provideNutritionService(retrofit: Retrofit): NutritionService {
        return retrofit.create(NutritionService::class.java)
    }

    @Singleton
    @Provides
    @JvmStatic
    fun provideRetrofit(okHttpClient: OkHttpClient): Retrofit {
        return Retrofit.Builder()
            .addConverterFactory(MoshiConverterFactory.create())
            .baseUrl("https://api.edamam.com/api")
            .client(okHttpClient)
            .build()
    }

    @Singleton
    @Provides
    @JvmStatic
    fun provideOkHttp(): OkHttpClient {
        return OkHttpClient()
            .newBuilder()
            .addInterceptor(ApiInterceptor())
            .build()
    }

    private class ApiInterceptor : Interceptor {
        override fun intercept(chain: Interceptor.Chain): Response {
            val request = chain.request().newBuilder()
            request
                .addHeader("api_id", “abc")
                .addHeader("app_key", “123")
            return chain.proceed(request.build())
        }
    }
}

@Module
object NutritionModule {

    @Singleton
    @Provides
    @JvmStatic
    fun provideNutritionRepository(nutritionService: NutritionService): NutritionRepository {
        return NutritionRepository(nutritionService)
    }
}

@Module(subcomponents = [MainActivityComponent::class], includes = [MainModule::class])
abstract class ActivityMainModule {
    @Binds
    @IntoMap
    @ClassKey(MainActivity::class)
    abstract fun bindAndroidInjector(factory: MainActivityComponent.Factory): AndroidInjector.Factory<*>
}

@Module
object MainModule {

    @Singleton
    @Provides
    @JvmStatic
    fun provideMainViewModelFactory(nutritionRepository: NutritionRepository): MainViewModel.Factory {
        return MainViewModel.Factory(nutritionRepository)
    }

    @Provides
    @JvmStatic
    fun provideMainViewModel(
        viewModelFactory: MainViewModel.Factory,
        fragmentActivity: FragmentActivity
    ): MainViewModel {
        return ViewModelProviders.of(fragmentActivity, viewModelFactory)
            .get(MainViewModel::class.java)
    }
}

@ActivityScope
@Subcomponent
interface MainActivityComponent : AndroidInjector<MainActivity> {

    @Subcomponent.Factory
    interface Factory : AndroidInjector.Factory<MainActivity> {}
}

class MainActivity : DaggerAppCompatActivity() {

    @Inject
    lateinit var mainViewModel: MainViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        mainViewModel.liveDataFoodAnalysis.observe(this, Observer { food ->
            Log.d("Food answer", food.uri)
        })
        mainViewModel.getFoodAnalysisResponse("egg")
    }
}

Answer 1

You will have to annotate FeedMeApplicationComponent with @Singleton. because both NetworkModule and NutritionModule define @Provides functions scoped with @Singleton, any component that uses these modules must also specify its own scope as @Singleton.

From Dagger docs: -

Since Dagger 2 associates scoped instances in the graph with instances of component implementations, the components themselves need to declare which scope they intend to represent. For example, it wouldn’t make any sense to have a @Singleton binding and a @RequestScoped binding in the same component because those scopes have different lifecycles and thus must live in components with different lifecycles. To declare that a component is associated with a given scope, simply apply the scope annotation to the component interface.