如何使用匕首解决 ViewModel 中的 coroutineScope 依赖关系
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【中文标题】如何使用匕首解决 ViewModel 中的 coroutineScope 依赖关系【英文标题】:How to resolve coroutineScope dependency in a ViewModel using dagger 【发布时间】:2021-11-03 03:12:43 【问题描述】:我正在尝试将协程作用域注入到 viewModel,但我收到 dagger kotlinx.coroutines.CoroutineScope cannot be provided without an @Provides-annotated method.
的错误
Dagger 不知道如何在@Inject 中提供协程作用域
为此我添加了一个新的AppModule,带有一个getCoroutineScope函数,我应该如何在return语句中传递coroutineContext。
这是正确的方法吗?
关于我为什么要传递 coroutineScope 的上下文是为了更改在 unittest 中调度的内容。
错误信息
example/breakingbad/di/AppComponent.java:8: error: [Dagger/MissingBinding] kotlinx.coroutines.CoroutineScope cannot be provided without an @Provides-annotated method.
public abstract interface AppComponent
^
kotlinx.coroutines.CoroutineScope is injected at
com.example.breakingbad.viewModel.MainActivityViewModel(coroutineScopeProvider, …)
com.example.breakingbad.viewModel.MainActivityViewModel is injected at
com.example.breakingbad.CharactersFragment.viewModel
com.example.breakingbad.CharactersFragment is injected at
com.example.breakingbad.di.AppComponent.inject(com.example.breakingbad.CharactersFragment)
MainActivityViewModel
class MainActivityViewModel @Inject constructor(
private val coroutineScopeProvider: CoroutineScope? = null,
private val dataRepository: DataRepository
): ViewModel()
val _charactersLiveData = MutableLiveData<Result<ArrayList<Character>>>()
val charactersLiveData: LiveData<Result<ArrayList<Character>>> = _charactersLiveData
private val coroutineScope = getViewModelScope(coroutineScopeProvider)
fun fetchCharacters()
coroutineScope.launch
_charactersLiveData.value = dataRepository.getCharacters()
新创建的 AppModule - 我稍后将包含在 dagger AppComponent 中
@Module
class AppModule
@Provides
fun getCoroutineScope(): CoroutineScope
return CoroutineScope()
提前致谢 回复
编辑
感谢 Karunesh 的意见
我的单元测试出现错误
java.lang.NullPointerException
at kotlinx.coroutines.CoroutineContextKt.newCoroutineContext(CoroutineContext.kt:33)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch(Builders.common.kt:52)
at kotlinx.coroutines.BuildersKt.launch(Unknown Source)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch$default(Builders.common.kt:47)
at kotlinx.coroutines.BuildersKt.launch$default(Unknown Source)
at com.example.breakingbad.MainActivityViewModelTest.fetchCharacters(MainActivityViewModelTest.kt:60)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
at org.mockito.internal.runners.DefaultInternalRunner$1.run(DefaultInternalRunner.java:79)
at org.mockito.internal.runners.DefaultInternalRunner.run(DefaultInternalRunner.java:85)
at org.mockito.internal.runners.StrictRunner.run(StrictRunner.java:39)
at org.mockito.junit.MockitoJUnitRunner.run(MockitoJUnitRunner.java:163)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
MainActivityViewModelTest
@RunWith(MockitoJUnitRunner::class)
class MainActivityViewModelTest
@Mock
private lateinit var dataRepository: DataRepository
@Mock
private lateinit var applicationScope: CoroutineScope
@Mock
private lateinit var dataObserver: Observer<Result<List<Character>>>
@InjectMocks
private lateinit var mainActivityViewModel: MainActivityViewModel
@Test
fun fetchCharacters()
applicationScope.launch(Dispatchers.IO)
Mockito.`when`(dataRepository.getCharacters())
.thenReturn(Result.success(arrayListOf(Character(
name = "myName",
img = "image",
occupation = arrayListOf(),
status = "status",
nickname = "nickName",
appearance = arrayListOf()
))))
mainActivityViewModel.fetchCharacters()
verify(dataRepository).getCharacters()
Mockito.verify(dataObserver).onChanged(Result.success(listOf(Character (
name = "myName",
img = "image",
occupation = arrayListOf(),
status = "status",
nickname = "nickName",
appearance = arrayListOf()
))))
mainActivityViewModel.charactersLiveData.removeObserver(dataObserver)
MainActivityViewModel 供参考
class MainActivityViewModel @Inject constructor(
@ApplicationScope private val applicationScope: CoroutineScope,
private val dataRepository: DataRepository
): ViewModel()
val _charactersLiveData = MutableLiveData<Result<ArrayList<Character>>>()
val charactersLiveData: LiveData<Result<ArrayList<Character>>> = _charactersLiveData
fun fetchCharacters()
applicationScope.launch(Dispatchers.IO)
//_charactersLiveData.value = dataRepository.getCharacters()
_charactersLiveData.postValue(dataRepository.getCharacters())
【问题讨论】:
【参考方案1】:编写下面的代码来创建一个注释类并在你的 di 类中提供范围
@Retention(AnnotationRetention.BINARY)
@Qualifier
annotation class ApplicationScope
@ApplicationScope
@Provides
@Singleton
fun providesApplicationScope() = CoroutineScope(SupervisorJob())
如何实现:
class WhereCoroutineIsToBeInjected(
@ApplicationScope private val applicationScope: CoroutineScope
)
applicationScope.launch(Dispatchers.IO)
【讨论】:
我试过了,我得到了和以前一样的错误我会根据你的回答用我所做的更新qn 我该如何使用我的单元测试 既然,我用刀柄一定是原因 代码运行良好,但我认为我在单元测试中做错了,让我将错误添加到问题中 我想我已经用单元测试实现更新了这个问题。我没有正确传递所需的调度程序。请问我该如何解决这个问题以上是关于如何使用匕首解决 ViewModel 中的 coroutineScope 依赖关系的主要内容,如果未能解决你的问题,请参考以下文章
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