如何使用 Hilt 注入在 fragmentComponent 中安装视图模型？

Question

我想要范围 ViewModel，它是 Fragment 而不是活动的依赖项，

interface MarsRepository {
    suspend fun getProperties(): List<Mars>
}



@Module
@InstallIn(FragmentComponent::class)
class MarsRepositoryModule {
    
    @Provides
    fun bindRemoteMarsDataSource(): MarsRepository{
        return RemoteMarsStorageImp()
    }
}



class MarsViewModel @ViewModelInject constructor(private val repository: MarsRepository): ViewModel()



@AndroidEntryPoint
class MarsFragment: Fragment() {
    
    val viewModel by viewModels<MarsViewModel>()
}

但我得到了这个

/app/build/generated/source/kapt/debug/com/Sample/bestcase/DevByteApplication_HiltComponents.java:111: error: [Dagger/MissingBinding] com.Sample.domain.repository.MarsRepository cannot be provided without an @Provides-annotated method.
  public abstract static class SingletonC implements DevByteApplication_GeneratedInjector,
                         ^
      javax.inject.Provider<com.Sample.domain.repository.MarsRepository> is injected at
          com.Sample.bestcase.features.mars.MarsViewModel_AssistedFactory(repository)
      com.Sample.bestcase.features.mars.MarsViewModel_AssistedFactory is injected at
          com.Sample.bestcase.features.mars.MarsViewModel_HiltModule.bind(factory)
      java.util.Map<java.lang.String,javax.inject.Provider<androidx.hilt.lifecycle.ViewModelAssistedFactory<? extends androidx.lifecycle.ViewModel>>> is injected at
          androidx.hilt.lifecycle.ViewModelFactoryModules.ActivityModule.provideFactory(…, viewModelFactories)
      @dagger.hilt.android.internal.lifecycle.DefaultActivityViewModelFactory java.util.Set<androidx.lifecycle.ViewModelProvider.Factory> is requested at
          dagger.hilt.android.internal.lifecycle.DefaultViewModelFactories.ActivityEntryPoint.getActivityViewModelFactory() [com.Sample.bestcase.DevByteApplication_HiltComponents.SingletonC → com.Sample.bestcase.DevByteApplication_HiltComponents.ActivityRetainedC → com.Sample.bestcase.DevByteApplication_HiltComponents.ActivityC]
  The following other entry points also depend on it:
      dagger.hilt.android.internal.lifecycle.DefaultViewModelFactories.FragmentEntryPoint.getFragmentViewModelFactory() [com.Sample.bestcase.DevByteApplication_HiltComponents.SingletonC → com.Sample.bestcase.DevByteApplication_HiltComponents.ActivityRetainedC → com.Sample.bestcase.DevByteApplication_HiltComponents.ActivityC → com.Sample.bestcase.DevByteApplication_HiltComponents.FragmentC]

只有通过 ActivityComponent 安装才能工作

@Module
@InstallIn(ActivityComponent::class)
class MarsRepositoryModule { 
    @Provides
    fun bindRemoteMarsDataSource(): MarsRepository{
        return RemoteMarsStorageImp()
    }
}

当我跟踪代码时，它使用 DefaultActivityViewModelFactory 而不是 DefaultFragmentViewModelFactory

 /**
     * Hilt Modules for providing the activity level ViewModelFactory
     */
    @Module
    @InstallIn(ActivityComponent.class)
    public abstract static class ActivityModule {

        @NonNull
        @Multibinds
        abstract Map<String, ViewModelAssistedFactory<? extends ViewModel>> viewModelFactoriesMap();

        @Provides
        @IntoSet
        @NonNull
        @DefaultActivityViewModelFactory
        static ViewModelProvider.Factory provideFactory(
                @NonNull Activity activity,
                @NonNull Application application,
                @NonNull Map<String, Provider<ViewModelAssistedFactory<? extends ViewModel>>>
                        viewModelFactories) {
            // Hilt guarantees concrete activity is a subclass of ComponentActivity.
            SavedStateRegistryOwner owner = (ComponentActivity) activity;
            Bundle defaultArgs = activity.getIntent() != null
                    ? activity.getIntent().getExtras() : null;
            SavedStateViewModelFactory delegate =
                    new SavedStateViewModelFactory(application, owner, defaultArgs);
            return new HiltViewModelFactory(owner, defaultArgs, delegate, viewModelFactories);
        }
    }

    /**
     * Hilt Modules for providing the fragment level ViewModelFactory
     */
    @Module
    @InstallIn(FragmentComponent.class)
    public static final class FragmentModule {

        @Provides
        @IntoSet
        @NonNull
        @DefaultFragmentViewModelFactory
        static ViewModelProvider.Factory provideFactory(
                @NonNull Fragment fragment,
                @NonNull Application application,
                @NonNull Map<String, Provider<ViewModelAssistedFactory<? extends ViewModel>>>
                        viewModelFactories) {
            Bundle defaultArgs = fragment.getArguments();
            SavedStateViewModelFactory delegate =
                    new SavedStateViewModelFactory(application, fragment, defaultArgs);
            return new HiltViewModelFactory(fragment, defaultArgs, delegate, viewModelFactories);
        }

        private FragmentModule() {
        }
    }

Answer 1

视图模型已被其片段限定。编译器试图告诉您的是，您正在尝试将 repository 注入到组件中，该组件的寿命比片段长。

正如它在组件部分中所说的here：

每个组件负责注入不同类型的 Android 类。如下表所示：

为了在视图模型中注入依赖项，它必须至少是ActivityRetainedScoped

---

修复

将FragmentComponent::class 更改为ActivityRetainedComponent::class 或SingletonComponent::class

@Module
@InstallIn(SingletonComponent::class) // or at least ActivityRetainedComponent
class MarsRepositoryModule { 
    @Provides
    fun bindRemoteMarsDataSource(): MarsRepository{
        return RemoteMarsStorageImp()
    }
}