我在使用 Dagger 2.2 实现 MultiBinding 时遇到问题。我正在使用带有 MVVM 架构的 Dagger 。我注入(inject)了 ViewModelProvideFactory
构造函数并绑定(bind)了模块的依赖项。
我已经从 youtube 上学习了 Mitch 的教程
https://www.youtube.com/watch?v=DToD1W9WdsE&list=PLgCYzUzKIBE8AOAspC3DHoBNZIBHbIOsC&index=13
我在这些链接上搜索了解决方案,但仍然面临同样的问题。
Dagger2: ViewModel cannot be provided without an @Provides-annotated method
https://github.com/google/dagger/issues/1478
代码 fragment
ViewModelKey
@MapKey
@Documented
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface ViewModelKey {
Class<? extends ViewModel> value();
}
ViewModelFactoryModule
/**
* ViewModelFactoryModule responsible for providing [ViewModelProviderFactory]
*
* Annotated with Module to tell dagger it is a module to provide [ViewModelProviderFactory]
*
* Annotated with bind annotation to efficiently provide dependencies similar to provides annotation
*/
@Module
abstract class ViewModelFactoryModule {
@Binds
abstract fun bindViewModelFactory(viewModelFactory: ViewModelProviderFactory) : ViewModelProvider.Factory
}
ViewModelProviderFactory
@Singleton
class ViewModelProviderFactory @Inject
constructor(private val creators: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>) :
ViewModelProvider.Factory {
override fun <T : ViewModel> create(modelClass: Class<T>): T {
var creator: Provider<out ViewModel>? = creators[modelClass]
if (creator == null) { // if the viewmodel has not been created
// loop through the allowable keys (aka allowed classes with the @ViewModelKey)
for ((key, value) in creators) {
// if it's allowed, set the Provider<ViewModel>
if (modelClass.isAssignableFrom(key)) {
creator = value
break
}
}
}
// if this is not one of the allowed keys, throw exception
if (creator == null) {
throw IllegalArgumentException("unknown model class $modelClass")
}
// return the Provider
try {
return creator.get() as T
} catch (e: Exception) {
throw RuntimeException(e)
}
}
companion object {
private val TAG = "ViewModelProviderFactor"
}
}
堆栈跟踪
> Task :app:kaptDebugKotlin FAILED
e: /Users/fazal/Documents/fazal/demo/AdvanceDagger2/app/build/tmp/kapt3/stubs/debug/com/example/advancedagger2/di/AppComponent.java:22: error: [Dagger/MissingBinding] java.util.Map<java.lang.Class<? extends androidx.lifecycle.ViewModel>,javax.inject.Provider<androidx.lifecycle.ViewModel>> cannot be provided without an @Provides-annotated method.
public abstract interface AppComponent extends dagger.android.AndroidInjector<com.example.advancedagger2.BaseApplication> {
^
java.util.Map<java.lang.Class<? extends androidx.lifecycle.ViewModel>,javax.inject.Provider<androidx.lifecycle.ViewModel>> is injected at
com.example.advancedagger2.viewmodel.ViewModelProviderFactory(viewModelsMap)
com.example.advancedagger2.viewmodel.ViewModelProviderFactory is injected at
com.example.advancedagger2.ui.AuthActivity.viewModelFactory
com.example.advancedagger2.ui.AuthActivity is injected at
dagger.android.AndroidInjector.inject(T) [com.example.advancedagger2.di.AppComponent → com.example.advancedagger2.di.ActivityBuilderModule_ContributeAuthActivity.AuthActivitySubcomponent]
我已经降级了 Kotlin 版本,但仍然面临同样的问题。告诉我什么,我做错了吗?
编辑 1
我还通过 Activity 范围内的 AuthViewModel 提供 ViewModel。当 Activity 销毁其组件时,依赖项也会销毁。
AuthViewModelModule
@Module
abstract class AuthViewModelModule {
/**
* Binds the auth view model dependency with [ViewModelKey] to group similar [ViewModel]
*
* Under the hood it is providing [com.example.advancedagger2.viewmodel.AuthViewModel]
*/
@Binds
@IntoMap
@ViewModelKey(AuthViewModel::class)
abstract fun bindAuthViewModel(authViewModel: AuthViewModel) : ViewModel
}
ActivityBuilderModule
/**
* This Class {@linkplain ActivityBuilderModule} is responsible for for android injection
* for the activity with in the application to avoid the seprate injection in each activity
*
* {@linkplain dagger.android.AndroidInjection#inject(Activity)}
*
* {@link com.example.advancedagger2.viewmodel.AuthViewModel} can be access from Auth Activity
* only so it is the concept of sub-modules
*
*/
@Module
public abstract class ActivityBuilderModule {
@ContributesAndroidInjector(
modules = AuthViewModelModule.class
)
abstract AuthActivity contributeAuthActivity();
}
最佳答案
根据评论我已经解决了这个问题
Your factory probably shouldn't be @Singleton. It's lightweight, doesn't carry any state, and your viewmodels probably get bound in an activity related scope and aren't available in @Singleton anyways
我用 @Singleton
注释了工厂,它在 Activity 范围内不可用。我刚刚删除了 @Singleton
注释。一切都按预期工作
关于android - 错误 [Dagger/MissingBinding] androidx.lifecycle.ViewModelProvider.Factory cannot be provided without an @Provides-annotated method,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/56737938/