I have a simple Todo Compose View as ```class App...

# compose

[elye]

I have a simple Todo Compose View as

class AppViewModel : ViewModel() {
    private var todoList = listOf(
        TodoItem(0, "My First Task"),
        TodoItem(1, "My Second Task", true)
    )
    private val _todoListFlow = MutableStateFlow(todoList)

    val todoListFlow: StateFlow<List<TodoItem>> get() = _todoListFlow

    fun setUrgent(index: Int, value: Boolean) {
        val modified = todoList.toMutableList()
        modified[index] = modified[index].copy(urgent = value)
        todoList = modified
        _todoListFlow.value = modified
    }
}

val viewModel = AppViewModel()

@Composable
fun MyTodoList {
    val todoListState = viewModel.todoListFlow.collectAsState()

   LazyColumn(modifier = Modifier.fillMaxHeight()) {
        items(items = todoListState.value, itemContent = { item ->
            Row {
                Text(text = item.title)
                Checkbox(
                    checked = item.urgent,
                    onCheckedChange = {
                        val index = todoListState.value.indexOf(item)
                        viewModel.setUrgent(index, it)
                    }
                )
            }
        })
    }
}

But I dislike to update a field in the list, I have to create a modify list to pass to the stateFlow.

fun setUrgent(index: Int, value: Boolean) {
        val modified = todoList.toMutableList()
        modified[index] = modified[index].copy(urgent = value)
        todoList = modified
        _todoListFlow.value = modified
    }

I can fix it using Solution in https://stackoverflow.com/a/75004437/3286489, but feel it is wrong, as that solution is having MutableState in ViewModel.

I wonder how can I avoid the need to create the entire list to send through the StateFlow, if I just need to change a variable that update the compose view?

[Zun]

I’ve never directly tried to change a List. Have you considered using a reactive database such as Room and instead just update the entry in your database? Room will then emit the updated todo list

[Mark Murphy]

I can fix it using Solution in

That does not appear to be a solution to your problem. Your "problem" is:

I dislike to update a field in the list, I have to create a modify list to pass to the stateFlow

That seems to be what SnapshotStateList does (see its mutate() function), and SnapshotStateList is what backs mutableStateListOf(). If your sole concern is that you feel that the code for updating an immutable list is ugly, implement an extension function that hides the ugly bits.