Dagger-Hilt @ViewModelInject sharedViewModel 没有注入片段

Question

在片段和 activity 之间创建共享注入视图模型

共享视图模型已成功注入到父MyActivity 中，但在呈现子项时，应用程序因依赖项注入失败而崩溃。我在下面提供了导致问题的代码。

提供会话管理器：

@InstallIn(ApplicationComponent::class)
@Module
class AppModule {
    @Provides
    @Singleton
    fun provideSessionManager(
        networkClient: NetworkClient
    ): SessionManager {
        return SessionManager(networkClient)
    }
}

要注入共享视图模型：

class SharedViewModel @ViewModelInject constructor(
    private var sessionManager: SessionManager
) : ViewModel() {

    var name = MutableLiveData<String>("Shared View Model")
}

父片段 activity 和子片段都使用。

class MyActionFragment() : Fragment() {
    private val viewModel: SharedViewModel by viewModels()
    override fun onActivityCreated(savedInstanceState: Bundle?) {
       super.onActivityCreated(savedInstanceState)
       Timber.d("View Model Name 1: ${viewModel.name.value}") // This line crashes
    }
}

class MyActivity : AuthenticatedBaseActivity() {
    private val viewModel: SharedViewModel by viewModels()
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        Timber.d("View Model Name 2: ${viewModel.name.value}") // This line prints
    }
}

但是，当代码为运行时，请注意 activity 创建了 ViewModel 并访问了它的值，但是当片段尝试执行相同操作时，应用程序崩溃了：

**D/MyActivity: View Model Name 2: Shared View Model**
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.xxx.xxx, PID: 16630
    java.lang.RuntimeException: Cannot create an instance of class com.xxx.xxx.ui.main.SharedViewModel
        at androidx.lifecycle.ViewModelProvider$NewInstanceFactory.create(ViewModelProvider.java:221)
        at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:278)
        at androidx.lifecycle.SavedStateViewModelFactory.create(SavedStateViewModelFactory.java:106)
        at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:185)
        at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150)
        at androidx.lifecycle.ViewModelLazy.getValue(ViewModelProvider.kt:54)
        at androidx.lifecycle.ViewModelLazy.getValue(ViewModelProvider.kt:41)
        at com.xxx.xxx.ui.main.MyActionFragment.getViewModel(Unknown Source:2)
        at com.xxx.xxx.ui.main.MyActionFragment.onActivityCreated(**MyActionFragment.kt:140**)
        at androidx.fragment.app.Fragment.performActivityCreated(Fragment.java:2718)

此外，当我删除注入的 Hilt 依赖项时 sessionManager 片段和视图模型的创建没有问题。

已关注但运气不佳。

任何关于使用共享模型的 Hilt 视图模型依赖注入的帮助将不胜感激！谢谢！

Answer 1

您必须提供所有依赖项，在您的情况下未提供 NetworkClient

@Module
@InstallIn(ApplicationComponent::class)
object AppModule {

    @Singleton
    @Provides
    fun provideSessionManager(
        networkClient: NetworkClient
    ): SessionManager = SessionManager(networkClient)

    @Singleton
    @Provides
    fun provideNetworkClient() = NetworkClient()
}

在Activity或Fragment中使用@AndroidEntryPoint

@AndroidEntryPoint
class MyActionFragment() : Fragment()



@AndroidEntryPoint
class MyActivity : AuthenticatedBaseActivity()

Answer 2

在 activity 和片段之间共享数据。使用下面的代码。 Hilt doc 对我也不起作用。

在Activity

    private val vm by viewModels<StartVM>()

在片段中

private val vm: StartVM by lazy {
    obtainViewModel(requireActivity(), StartVM::class.java, defaultViewModelProviderFactory)
}

Kotlin 扩展

fun <T : ViewModel> Fragment.obtainViewModel(owner: ViewModelStoreOwner,
    viewModelClass: Class<T>,
    viewmodelFactory: ViewModelProvider.Factory
) =
    ViewModelProvider(owner, viewmodelFactory).get(viewModelClass)

Answer 3

您可以在Fragment中使用扩展函数:

class MyFragment: Fragment() {
    private val viewModel: SharedViewModel by activityViewModels()
}

并且在Activity中：

class MyActivity : Activity() {
    private val viewModel: SharedViewModel by viewModels()
}

Dagger-Hilt @ViewModelInject sharedViewModel 没有注入片段

Dagger-Hilt @ViewModelInject sharedViewModel not injecting into fragment

android

android-fragments

android-viewmodel

dagger-hilt