I am implementing a barcode scanner in Compose. Once it scans a barcode, it needs to do a network request to find the respective item. If an item is found I dismiss the scanner. If it is not found or some error happens, a dialog is shown. In order to accomplish that I think that I will need to do something along these lines:

data class DialogState(val isShown: Boolean = false, val message: String = "")

@Composable
fun Screen(navController: NavController, viewModel: MyViewModel) {
    val dialogState by rememberUpdateState(DialogState)
    val scope = rememberCoroutineScope()
    Button(onClick = { scope.launch { 
        when (val result = viewModel.doRequest()) {
           is Success -> navController.popBackStack()
           is NotFound -> dialogState = DialogState(true, "Not Found")
           else -> dialogState = DialogState(true, "error")
   }})
   if (dialogState.isShown) {
       AlertDialog(.......) 
   } 
          
}

Would this be correct ?

You more or less got the right idea. One suggestion though. i’m gonna assume your viewModel.doRequest() is a suspend function since you wrapped it in a coroutinescope. I would recommend NOT to expose public suspendable functions in your ViewModel to your view. Instead I would recommend using a regular function in the viewmodel and in the implementation of ViewModel, the function uses viewModelScope. And from there you can expose a flow/livedata/rxstream/MutableState for the Composable to observe. Psuedo code

class ViewModel {
    val resultFlow: StateFLow<Result>
     
    fun doRequest() { viewmodelScope.launch{ 
        val result = somerequest()
        resultFlow.value = result
    }
}

@Composable
fun ...() {
    val result viewModel.resultFLowObserveAsState()
    when (result) {
       ....
    }
}

Your

rememberUpdatedState

looks a bit suspicious - are you passing it a companion object? It's definitely not a parameter, which is basically all that function is intended for

@Zach Klippenstein (he/him) [MOD] It has a typo. Pease read it as

val dialogState by rememberUpdateState(DialogState())

The initial state is a new

DialogState

object created with default values for the params