Hi I am using clean architecture to develop app bu...

# android-architecture

[Lokik Soni]

Hi I am using clean architecture to develop app but I am confusing in sending states from ViewModel to Compose Screen i.e State to show Sanckbar and State to navigate.
I am getting confuse in handling that state in Compose. Please see the code below:

[Lokik Soni]

State

data class AddEditNoteState(
   val title: String = "",
   val isNoteSaved: Boolean = false,
   val errorMsg: String? = null
)

ViewModel

class AddEditNoteViewModel @Inject constructor(
   savedStateHandle: SavedStateHandle,
   private val _addNoteUseCase: AddNoteUseCase,
   private val _getNoteById: GetNoteUseCase
): ViewModel() {

   // TODO may not need stateIn
   private val _addEditNoteSate = MutableStateFlow(AddEditNoteState())
   val addEditNoteState = _addEditNoteSate
      .asStateFlow()
      .stateIn(viewModelScope, WhileViewSubscribed, AddEditNoteState())

   fun onEvent(addEditNoteEvent: AddEditNoteEvent) {

		when(addEditNoteEvent) {
			is AddEditNoteEvent.SaveNote -> {
				viewModelScope.launch {
					try {
						_addNoteUseCase(
							Note(
								title = _addEditNoteSate.value.title,
							)
						)
						_addEditNoteSate.update { it.copy(isNoteSaved = true, errorMsg = null,) }

					} catch (e: NoteAppException.InvalidNoteException) {
						_addEditNoteSate.update { it.copy(isNoteSaved = false, errorMsg = e.msg) }
					}
				}
			}
		}
	}
}

In viewmodel if not saved success I want to navigate back but on error want to show snackbar.
So for this should I create two LaunchEffect for navigate and snackbar or it is not good to have two LaunchEffect.
In Compose Screen

val message = addEditNoteState.errorMsg
message?.let { msg ->
   LaunchedEffect(scaffoldState, msg) {
      scaffoldState.snackbarHostState.showSnackbar(message = msg)
   }
}

Currently I have handled only snackbar state like above.
I want to follow Google recommended one-off ViewModel event.

[Colton Idle]

one off event from VM is described as an antipattern from google:
https://medium.com/androiddevelopers/viewmodel-one-off-event-antipatterns-16a1da869b95

[Colton Idle]

the arch docs show an example of how to properly use state for displaying a snackbar https://developer.android.com/topic/architecture/ui-layer/events#compose_3