How to correctly store a list in a mutablestate re...

# compose

[Pablo]

How to correctly store a list in a mutablestate remember variable? I tried with val imagesList by remember *{* _mutableStateListOf_<ImageModel>()*}* but it gives this error Type 'TypeVariable(T)' has no method 'getValue(Nothing?, KProperty<*>)' and thus it cannot serve as a delegate
If I replace by remember with = remember the error dissapears and I dont understand why. Also, the guides says by remember is the correct option so I whould like to understand how to be able to use by remember with this list. Another problem I found is that even using = instead of by, I'm not able to init the variable with a list. remember *{* _mutableStateListOf_<ImageModel>(ImageModelProvider.imageModelList)*}* gives this error: Type mismatch. Required: ImageModel Found:List<ImageModel>

[ephemient]

with MutableState, you can either destructure it to a getter and setter, or operate with its .value getter and .setValue() setter, or use var by delegation to handle that for you

[ephemient]

with SnapshotStateList (returned from mutableStateListOf()), you simply use `.get()`/`.set()` (e.g. [] indexing operators) as normal. so it's =

[ephemient]

it's not a MutableState<List>, it's a MutableList that allows Compose to observe changes

[Pablo]

Well I'm exactly in the same point than before. Maybe can you show me a working sample for initialize that list correctly with by remember and those initial values?

[ephemient]

what you have written is basically the same as writing `mutableListOf(imageModelList)`; it is a list of a single list, not a list of its elements. to convert a list to a mutable state list, you use the conversion function

val imagesList = remember { ImageModelProvider.imageModelList.toMutableStateList() }

[ephemient]

this is covered in the docs, https://developer.android.com/codelabs/jetpack-compose-state#10

[Pablo]

so it is not allowed to use by here, must be used =

[Zach Klippenstein (he/him) [MOD]]

If your ViewModel is the source of truth and you’re getting a new list from your view model when it changes, store the list in a mutableStateOf and just put the new list in there every time you get a new one.

If the list you’re creating in the remember is the source of truth, use mutableStateListOf and then you can mutate the list directly without having to create a whole new list every time. (You can technically use this approach if your VM is the source of truth too but there’s no advantage, you’d have to clear then addAll every time.)