Save User State

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

Lesson 06: CRUD Operations

Demo: Update & Delete Notes from Room Database

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In this section, you’ll add the remaining CRUD operations - update and delete. These new functions will be added to your DAO and repository to update and delete Room database notes.

@Update
suspend fun update(note: NoteEntity)

@Delete
suspend fun delete(note: NoteEntity)

suspend fun update(noteEntity: NoteEntity)

suspend fun delete(noteEntity: NoteEntity)

override suspend fun update(noteEntity: NoteEntity) {
  withContext(ioDispatcher) {
    notesDao.update(noteEntity)
  }
}

override suspend fun delete(noteEntity: NoteEntity) {
  withContext(ioDispatcher) {
    notesDao.delete(noteEntity)
  }
}

data object UpdateNote : CreateNoteEvents

CreateNoteEvents.UpdateNote -> {
  if (createNoteState.value.isValid()) {
    viewModelScope.launch {
      val noteEntity = NoteEntity(
        id = currentNote.value?.id ?: 0,
        title = createNoteState.value.title ?: "",
        description = createNoteState.value.description ?: "",
        priority = createNoteState.value.priority ?: "",
        timestamp = System.currentTimeMillis(),
        noteLocation = createNoteState.value.noteLocation ?: ""
      )
      notesRepository.update(noteEntity)
    }
  }
}

private val _currentNote = MutableStateFlow<NoteEntity?>(null)
val currentNote = _currentNote.asStateFlow()

fun updateNoteWithPreviousDetails(noteEntity: NoteEntity) {
  _currentNote.update {
    noteEntity
  }
  _createNoteState.update {
    it.copy(
      title = noteEntity.title,
      description = noteEntity.description,
      priority = noteEntity.priority,
      noteLocation = noteEntity.noteLocation
    )
  }
}

viewModel.updateNoteWithPreviousDetails(it)

UpdateNoteScreenContent(
  createNoteState = createNoteState,
  onTitleChange = { title ->
    viewModel.handleCreateNoteEvents(CreateNoteEvents.TitleChanged(title))
  },
  onDescriptionChange = { description ->
    viewModel.handleCreateNoteEvents(CreateNoteEvents.DescriptionChanged(description))
  },
  onPriorityChange = { priority ->
    viewModel.handleCreateNoteEvents(CreateNoteEvents.PriorityChanged(priority))
  },
  onUpdateNote = {
    viewModel.handleCreateNoteEvents(CreateNoteEvents.UpdateNote)
    navigateToHome()
  },
  onNoteLocationChange = { noteLocation ->
    viewModel.handleCreateNoteEvents(CreateNoteEvents.NoteLocationChanged(noteLocation))
  }
)

fun delete(noteEntity: NoteEntity) {
  viewModelScope.launch {
    notesRepository.delete(noteEntity)
  }
}

viewModel.delete(it)
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