Kotlin 使用 Hilt 提供首选项数据存储

发布于02月08日

I was trying to provide a common DataStore<Preferences> so that the same preference file could be used in multiple places but I got the helpful error message:

找不到符号:DaggerMyApplication\u HiltComponents\u SingletonC.建筑商()

@Module
@InstallIn(ApplicationComponent::class)
object DataStoreModule {
    
    @Provides
    fun provideDataStore(@ApplicationContext context: Context): DataStore<Preferences> = context.createDataStore("settings")
}

I can however do the following and use it within an @Inject constructor.

@Singleton
class DataStoreProvider @Inject constructor(@ApplicationContext context: Context) {

    val dataStore: DataStore<Preferences> = context.createDataStore("settings")
}

我假设扩展createDataStore正在做一些Hilt不喜欢的事情，但我希望能解释一下发生了什么，即使这个问题是无法解决的.

推荐答案

This worked for me:

    @Provides
    @Singleton
    fun dataStore(@ApplicationContext appContext: Context): DataStore<Preferences> =
        appContext.createDataStore("settings")

The idea is putting @Singleton behind the provider method.

Update on Feb 9, 2021:
Preferably, create a manager and provide that:

class DataStoreManager(appContext: Context) {

    private val settingsDataStore = appContext.createDataStore("settings")

    suspend fun setThemeMode(mode: Int) {
        settingsDataStore.edit { settings ->
            settings[Settings.NIGHT_MODE] = mode
        }
    }

    val themeMode: Flow<Int> = settingsDataStore.data.map { preferences ->
        preferences[Settings.NIGHT_MODE] ?: AppCompatDelegate.MODE_NIGHT_UNSPECIFIED
    }

}

AppModule:

@InstallIn(SingletonComponent::class)
@Module
class AppModule {
    @Provides
    @Singleton
    fun dataStoreManager(@ApplicationContext appContext: Context): DataStoreManager =
        DataStoreManager(appContext)

Update on March 20, 2021:
Version 1.0.0-alpha07

private val Context.dataStore by preferencesDataStore("settings")

class DataStoreManager(appContext: Context) {

    private val settingsDataStore = appContext.dataStore

    suspend fun setThemeMode(mode: Int) {
        settingsDataStore.edit { settings ->
            settings[Settings.NIGHT_MODE] = mode
        }
    }

    val themeMode: Flow<Int> = settingsDataStore.data.map { preferences ->
        preferences[Settings.NIGHT_MODE] ?: AppCompatDelegate.MODE_NIGHT_UNSPECIFIED
    }
}

Update on May 1, 2021:

移除dataStoreManager个提供者.然后

private val Context.dataStore by preferencesDataStore("settings")

@Singleton //You can ignore this annotation as return `datastore` from `preferencesDataStore` is singletone
class DataStoreManager @Inject constructor(@ApplicationContext appContext: Context) {

    private val settingsDataStore = appContext.dataStore

    suspend fun setThemeMode(mode: Int) {
        settingsDataStore.edit { settings ->
            settings[Settings.NIGHT_MODE] = mode
        }
    }

    val themeMode: Flow<Int> = settingsDataStore.data.map { preferences ->
        preferences[Settings.NIGHT_MODE] ?: AppCompatDelegate.MODE_NIGHT_UNSPECIFIED
    }

}