```private fun <T : Any> SavedStateHandle.sa...

# compose

[Marko Novakovic]

private fun <T : Any> SavedStateHandle.saveableMutableStateOf(
    key: String,
    saver: Saver<T, out Any> = autoSaver(),
    init: () -> T,
): MutableState<T> {
    @Suppress("UNCHECKED_CAST")
    (saver as Saver<T, Any>)
    val value = mutableStateOf(restoreOrInit(key, saver, init))
    saveToStateHandle(key, saver, value)
    return value
}

private fun <T : Any> SavedStateHandle.restoreOrInit(
    key: String,
    saver: Saver<T, Any>,
    init: () -> T,
): T = run {
    val restored = get<Bundle>(key)?.get("value")?.let(saver::restore)
    restored ?: init()
}

private fun <T : Any> SavedStateHandle.saveToStateHandle(
    key: String,
    saver: Saver<T, Any>,
    value: MutableState<T>,
) = setSavedStateProvider(key) {
    val saverScope = SaverScope { true }
    with(saver) {
        bundleOf("value" to saverScope.save(value.value))
    }
}

...
//usage
private var _state by savedStateHandle.saveableMutableStateOf(STATE) { initialState }

this used to work but now in 1.2.0-alpha07 setting _state doesn’t save value to SavedStateHandle

[Alex Vanyo]

How are you checking whether the value is saved to the SavedStateHandle? The saved state provider utility will only save the value when the entire SavedStateHandle is being saved, so just setting _state won’t immediately change what is stored in the SavedStateHandle.

Also the latest versions of androidx.lifecycle (2.5.0-beta01 was just released!) now includes some of these utilities that you can use.

[Marko Novakovic]

I don’t quite understand what you are trying to say.
btw, are there any examples of how can I bridge SavedStateHandle and MutableState?

[Marko Novakovic]

this is how I use this extension, but it worked and idk when it just stopped working. I ran my unit tests and this one was failing. then I ran the app and tested and state is not neither saved nor restored

abstract class StateStore<State : Any>(
    savedStateHandle: SavedStateHandle,
    initialState: State,
) : ViewModel() {

    private var _state: State by savedStateHandle.saveableMutableStateOf(STATE) { initialState }
    val state: State
        get() = _state

    fun updateState(reducer: State.() -> State) {
        _state = state.reducer()
    }

    companion object {
        private const val STATE = "state"
    }
}

[Alex Vanyo]

In unit tests how are you checking saved state?

And yep! There are examples in the docs here using the new built-in versions of these utilities:
https://developer.android.com/reference/kotlin/androidx/lifecycle/SavedStateHandle#(androidx.lifecycle.SavedStateH[…]aveable.Saver,kotlin.Function0)

[Marko Novakovic]

private var _state: State by savedStateHandle.saveable(STATE) { mutableStateOf(initialState) }
    val state: State
        get() = _state

this doesn’t work, am I doing it right? that’s how it is in the docs. I tried with the app, not unit tests this time

[Alex Vanyo]

Yeah, that should work it seems… can you open up a bug with a reproducing sample for us to take a look at?

[Alex Vanyo]

https://issuetracker.google.com/issues/new?component=413132&template=1096619 should be the correct link

[Marko Novakovic]

I will, thanks for the link