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Hey guys, I am working on changing background color of button. I want to know my example is good to use simple business logic in `viewmodel` with `LaunchEffect` . If there is any problem or better way please guide me on this. Thanks

```@Composable
fun ItemColorStateful() {
    var index by remember { mutableStateOf(-1) }
    val vm = koinViewModel&lt;ColorViewModel&gt;()
    LaunchedEffect(key1 = index) {
        vm.changeBackgroundColor(index)
    }
    Column(modifier = Modifier.fillMaxSize()) {
        Text(text = "Different Color")
        ButtonScopeStateless(
            index = index,
            onIndexChange = {
                index = it
            },
            backgroundColor = vm.backgroundColor
        )
    }
}

class ColorViewModel : BaseViewModel() {
    var backgroundColor by mutableStateOf(Color.Blue)

    fun changeBackgroundColor(index: Int) {
        backgroundColor = if (index != -1) {
            Color.Gray
        } else {
            Color.Blue
        }
    }
}

@Composable
fun ButtonScopeStateless(
    index: Int,
    onIndexChange: (Int) -&gt; Unit,
    backgroundColor: Color,
) {
    Button(
        colors = ButtonDefaults.buttonColors(backgroundColor = backgroundColor),
        onClick = { onIndexChange(index + 1) }
    ) {
        Text(text = "Click Me $index")
    }
}```


My main goal is to avoid business logic in `Composable` function.

Your approach makes only sense if you want to do something else with `backgroundColor` except simply changing its value

yes i'll change with different colors with specfic number

If you dont need backgroundColor outside of Compose, you can set value of index directly and Compose will automatically recompose the related components since you have defined you index as `mutableStateOf`

How can I set the background color? Sorry I didn't get it. Can you please provide me example?

What you are doing is correct, but you dont have to involve a viewmodel if you don't need `backgroundColor` outside of Compose scope

Yes I don't need `backgroundColor` outside of compose. I used viewmodel because It can be used for unit testing. Composable functions are not testable.

In my mentor project, testing is mandatory. I cannot find code coverage for composable stuffs. So that's why I moved to all business logic to viewmodel

If you just want to demonstrate how to extract business logic, then it's done properly

Thank you for your guidance. It clears my doubts.