未在 StateFlow observable 中接收更新

Question

I have two classes

class ChildFragment : ParentFragment {
           viewModel.location.collectLatest { result ->
                when (result) {
                    is LocationResult.Unit -> {}
                    is LocationResult.Error -> {}
                    is LocationResult.Success -> {} // Not recieving callback here.
                }
            }
}
class ChildViewModel : ParentViewModel

class ParentFragment
class ParentViewModel {
    private val _location = MutableStateFlow<LocationResult>(LocationResult.Unit)
    val location = _location.asStateFlow()

    fun updateLocation(location: Location) {
        _location.value = LocationResult.Success(location)
    }
}

I am receiving the first Unit result in the flow callback but does not receive it once I call the update method.

Anything, in particular, that is being done wrong? Please help.

Answer 1

I would suggest at your fun updateLocation , implement also with the others like below

fun updateLocation(location: Location) {
    try {
        _location.value = LocationResult.Success(location)
    } catch (e: Exception) {
        _location.value = LocationResult.Error(e.message)
    }
}

with this LocationResult.Error , you are able to know if there is any error or not. Please not to avoid any exception for futures.