如何使用 Dagger Hilt 在动态功能模块中创建 ViewModel？

Question

尝试在具有 private val viewModel: PostDetailViewModel by viewModels()

的动态功能模块中创建 ViewModel

片段中

class PostDetailFragment : DynamicNavigationFragment<FragmentPostDetailBinding>() {

    private val viewModel: PostDetailViewModel by viewModels()
    
    override fun getLayoutRes(): Int = R.layout.fragment_post_detail

    override fun bindViews() {
        // Get Post from navigation component arguments
        val post = arguments?.get("post") as Post
        dataBinding.item = post
        viewModel.updatePostStatus(post)
        
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        initCoreDependentInjection()
        super.onCreate(savedInstanceState)
    }

    private fun initCoreDependentInjection() {

        val coreModuleDependencies = EntryPointAccessors.fromApplication(
            requireActivity().applicationContext,
            DomainModuleDependencies::class.java
        )

        DaggerPostDetailComponent.factory().create(
            coreModuleDependencies,
            requireActivity().application
        )
            .inject(this)

    }
}

结果错误

Caused by: java.lang.InstantiationException: java.lang.Class<com.x.post_detail.PostDetailViewModel> has no zero argument constructor

它适用于应用程序模块中的任何片段，但不适用于动态功能模块。将 ViewModel 添加到动态功能模块的正确方法是什么？我应该使用 ViewModelFactory 在应用模块中创建 ViewModel 并从应用模块获取它们吗？

Answer 1

基于此官方 github 帖子

There's documentation on Hilt and DFM now at https://developer.android.com/training/dependency-injection/hilt-multi-module#dfm

In general though, because we're built off of subcomponents and monolithic components you won't be able to use the standard Hilt mechanisms like @AndroidEntryPoint with DFM.

Unfortunately, no. @ViewModelInject uses the Hilt ActivityRetainedComponent which is monolithic, so any @ViewModelInject class in your DFM won't be recognized.

目前看来，在动态功能模块中仅使用 @ViewModelInject 和 by viewModels() 注入到 ViewModel 似乎是不可能的。

基于 plaid 应用程序，我在动态功能模块中重建了我的 Dagger 模块

@InstallIn(FragmentComponent::class)
@Module
class PostDetailModule {

    @Provides
    fun providePostDetailViewModel(fragment: Fragment, factory: PostDetailViewModelFactory) =
        ViewModelProvider(fragment, factory).get(PostDetailViewModel::class.java)

    @Provides
    fun provideCoroutineScope() = CoroutineScope(Dispatchers.Main.immediate + SupervisorJob())

}

而 ViewModel 和 ViewModelFactory 是

class PostDetailViewModel @ViewModelInject constructor(
    private val coroutineScope: CoroutineScope,
    private val getPostsUseCase: UseCase
) : ViewModel() {
 
    // Do other things
}

class PostDetailViewModelFactory @Inject constructor(
    private val coroutineScope: CoroutineScope,
    private val getPostsUseCase: UseCase
) : ViewModelProvider.Factory {

    @Suppress("UNCHECKED_CAST")
    override fun <T : ViewModel> create(modelClass: Class<T>): T {
        if (modelClass != PostDetailViewModel::class.java) {
            throw IllegalArgumentException("Unknown ViewModel class")
        }
        return PostDetailViewModel(
            coroutineScope,
            getPostsUseCase
        ) as T
    }
}

并注入动态特征模块中的片段

class PostDetailFragment : Fragment() {

    @Inject
    lateinit var viewModel: PostDetailViewModel


    override fun onCreate(savedInstanceState: Bundle?) {
        initCoreDependentInjection()
        super.onCreate(savedInstanceState)
    }

    private fun initCoreDependentInjection() {

        val coreModuleDependencies = EntryPointAccessors.fromApplication(
            requireActivity().applicationContext,
            DomainModuleDependencies::class.java
        )

        DaggerPostDetailComponent.factory().create(
            dependentModule = coreModuleDependencies,
            fragment = this
        )
            .inject(this)
    }
}

如何使用 Dagger Hilt 在动态功能模块中创建 ViewModel？

How to create ViewModel in dynamic feature module with Dagger Hilt?

android

android-viewmodel

dynamic-feature-module

dagger-hilt