i might be misunderstanding how `rememberSaveable...

# compose-desktop

[Nikky]

i might be misunderstanding how rememberSaveable works
but i have a few tabs in my app set up with a when (index) 0 -> tabOne() 1 -> tabTwo() } to switch the content
in the content of these tabs i use var text by rememberSaveable(key = "textfield") { mutableStateOf(TextFieldValue("")) }

but every time the tab changes and come back the value resets to empty?

does this get wiped every time it does not get rendered ?

how would i solve this in a way that does not involve storing my own global state (mutablestateflow) for each thing ?

[MR3Y]

This is expected because when you move to a new tab you're disposing the current tab from Composition (based on the way you do it right now) and so any state attached with it will be cleared

[eygraber]

Even when using rememberSaveable?

[MR3Y]

@eygraber Yes, AFAIK. rememberSaveable helps you in saving things like scrolling position on desktop and of course surviving config changes on Android
but basically when you do something like this:

when(something) {
   1 -> show some composable
   2 -> show another composable
}

the two conditions are mutually exclusive so they won't be in composition at the same time.

[MR3Y]

if you want to use rememberSaveable here you'll need to hoist it somewhere up the tree

[Nikky]

so when i switch from 1 to 2 it discards ALL state in branch 1 ?

[MR3Y]

@Nikky yep exactly

[Nikky]

quite annoying since this is a deepdly nested UI with lists of different lengths

[Nikky]

this is what we are doing

https://nikky.catgirl.host/i/cgau2vw8.png▾

and i think the "correct" solution here is to store it all in some stateflow and write / read then out of a map by key

[Nikky]

using a global

private val expandedStates = mutableStateMapOf<String, Boolean>()

fixed the problem.. and now i also understand why, thanks

[SaurabhS]

To use rememberSaveable with tabs you can use:
https://developer.android.com/reference/kotlin/androidx/compose/runtime/saveable/SaveableStateHolder

[Nikky]

so i guess i could pass some MapString, Boolean through that Saveable state holder ?

but i don't actually need it to be saveable.. i just want it to not loose its state when the composition gets discared as you navigate around.. a global to store these flags works well enough and does not complicate the code as much

good to know it exists though.. i am sure there is usecases where i will remember and use this

[Alexander Maryanovsky]

That’s exactly what SaveableStateHolder does