Save User State

Sep 10 2024 · Kotlin 1.9, Android 14, Android Studio Koala | 2024.1.1

Lesson 06: CRUD Operations

Demo: Create & Read Notes from Room Database

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In this section, you’ll create a repository that performs some of the CRUD operations from your database.

suspend fun saveNote(noteEntity: NoteEntity)
fun getNotes(): Flow<List<NoteEntity>>

class NotesRepositoryImpl(
  private val ioDispatcher: CoroutineDispatcher,
  private val notesDao: NotesDao
): NotesRepository {
  override suspend fun saveNote(noteEntity: NoteEntity) {
    withContext(ioDispatcher) {
      notesDao.insert(noteEntity)
    }
  }

  override fun getNotes(): Flow<List<NoteEntity>> {
    return notesDao.getNotes()
  }
}

val dispatcherModule = module { single { Dispatchers.IO } }

val repositoryModule = module {
  single<NotesRepository> { NotesRepositoryImpl(get(), get()) }
}

val appModules = listOf(
  dataStoreModule,
  viewModelModule,
  notesFileManagerModule,
  roomDatabaseModule,
  repositoryModule,
  dispatcherModule
)

class MainViewModel(
  private val dataStoreManager: DataStoreManager,
  private val internalNotesFileManager: InternalNotesFileManager,
  private val externalNotesFileManager: ExternalNotesFileManager,
  private val notesRepository: NotesRepository
): ViewModel() {
  // Rest of the code
}

"Room Database" -> {
  notesRepository.saveNote(noteEntity)
}

private fun fetchNotes() {
  viewModelScope.launch {
    notesRepository.getNotes().collect { notes ->
      _notes.update {
        notes + externalNotesFileManager.readTextFile() + internalNotesFileManager.readTextFile()
      }
    }
  }
}

  viewModel { MainViewModel(get(), get(), get(), get()) }
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