Hilt ViewModel 构造函数在导航组件范围内不起作用

Question

这是我第一次玩 Hilt。我用 BottomNavigationView 创建了一个演示应用程序。我添加了 @AndroidEntryPoint 和 @HiltAndroidApp。我创建了一个模块 class 并注入了 ViewModel，但我仍然一遍又一遍地遇到同样的错误。

Class <ViewModel> has no zero argument constructor

一些代码：

@HiltAndroidApp
class MyApplication: Application() {
}

<application
    android:name=".MyApplication"

@AndroidEntryPoint
class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val navView: BottomNavigationView = findViewById(R.id.nav_view)

        val navController = findNavController(R.id.nav_host_fragment)
        navView.setupWithNavController(navController)
    }
}

@AndroidEntryPoint
class CampaignsFragment : Fragment() {

    private var _binding: FragmentCampaignsBinding? = null
    private val binding get() = _binding!!

    private val campaignsViewModel: CampaignsViewModel by navGraphViewModels(R.id.mobile_navigation) {
        defaultViewModelProviderFactory
    }

    override fun onCreateView(
            inflater: LayoutInflater,
            container: ViewGroup?,
            savedInstanceState: Bundle?
    ): View? {
        _binding = FragmentCampaignsBinding.inflate(inflater, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        campaignsViewModel.getCampaigns()
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }
}

class CampaignsViewModel @ViewModelInject constructor(
    private val db: FirebaseFirestore,
    @Assisted private val savedStateHandle: SavedStateHandle
): ViewModel() {

    fun getCampaigns() {
        db.collection("campaigns")
            .get()
            .addOnSuccessListener {
                for (document in it) {
                    Log.d(BuildConfig.BUILD_TYPE, "${document.id} => ${document.data}")
                }
            }
            .addOnFailureListener {

            }
    }
}

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

    @Provides
    fun provideFirebaseFirestore(): FirebaseFirestore {
        return Firebase.firestore
    }
}

我已经添加了我正在使用的所有代码。我错过了什么吗？我找不到任何示例或遗漏的错误。我确实阅读了有关 ViewModel 和实现的刀柄文档。

app gradle 文件内容：

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'com.google.gms.google-services'
    id 'kotlin-android-extensions'
    id 'kotlin-kapt'
    id 'dagger.hilt.android.plugin'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.2"

    defaultConfig {
        applicationId "ro.marianpavel.partidulverde"
        minSdkVersion 21
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    buildFeatures {
        viewBinding true
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
}

dependencies {

    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation 'androidx.core:core-ktx:1.3.2'
    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'com.google.android.material:material:1.2.1'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.2'
    implementation 'androidx.navigation:navigation-fragment-ktx:2.3.1'
    implementation 'androidx.navigation:navigation-ui-ktx:2.3.1'
    implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.2.0'
    implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0'
    implementation 'androidx.navigation:navigation-fragment-ktx:2.3.1'
    implementation 'androidx.navigation:navigation-ui-ktx:2.3.1'
    implementation platform('com.google.firebase:firebase-bom:25.12.0')
    implementation 'com.google.firebase:firebase-analytics-ktx'
    implementation 'com.google.firebase:firebase-firestore-ktx'
    testImplementation 'junit:junit:4.13.1'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'

    implementation "com.google.dagger:hilt-android:2.29-alpha"
    implementation 'androidx.hilt:hilt-lifecycle-viewmodel:1.0.0-alpha02'
    kapt "com.google.dagger:hilt-android-compiler:2.29-alpha"
}

Answer 1

我认为这可能与您提供 firebase dependency 的方式有关。使用 FragmentComponent::class，您的 ViewModel 无法访问此依赖项。当用 ApplicationComponent::class.

更改它时，这应该有效

另一个问题可能是您在 gradle

中缺少 kapt "com.google.dagger:hilt-android-compiler:$dagger_hilt_version" 和 kapt "androidx.hilt:hilt-compiler:$dagger_hilt_lc_version"

Hilt ViewModel 构造函数在导航组件范围内不起作用

Hilt ViewModel constructor not working when navigation component scope

android

dagger-hilt