Compose Snackbar not appearing on repeated error

Question

I am new to jetpack compose and is trying to show an error snackbar whenever the error message I am observing is not null.

Scaffold(scaffoldState = scaffoldState) {
        LaunchedEffect(errorMessage) {
            if (errorMessage != null) {
                scope.launch {
                    scaffoldState.snackbarHostState.showSnackbar(errorMessage)
                }
            }
        }
        Column(horizontalAlignment = Alignment.CenterHorizontally) {
              //some ui components inside here
        }
    }

The issue in the above code is that, the first time the error message changes from null to a particular message it appears fine. However on a repeated user action that produces the same error message it's not coming again.

P.S - I know this is happening due to placing the errorMessage as key inside the LaunchedEffect. My doubt is that, is there a different approach to achieve what I want?

Answer 1

This is happening because the LaunchedEffect will run again just in case the errorMessage has changed. What you can do is:

LaunchedEffect(errorMessage) {
   if (errorMessage != null) {
        resetErrorMessage() // reset errorMessage
        scope.launch {
            scaffoldState.snackbarHostState.showSnackbar(errorMessage)
        }
   }
}

The resetErrorMessage must set the errorMessage to null, so the LaunchedEffect will run again, but since you're checking if it is not null, nothing will happen. But as soon you receive a new error message, the LaunchedEffect will be executed again.