Hello, does anyone understand when you should use viewmodel + mutablestateOf() vs. using remember?

# compose

[John Aoussou]

Hello, does anyone understand when you should use viewmodel + mutablestateOf() vs. using remember?

[nilTheDev]

I hardly use mutableStateOf in any composable. All states and events are hosted in the viewModel and exposed with flows .

[John Aoussou]

But do you use remember? I'm confused about how viewmodel interacts with remember, or if you only use one or the other.

[nilTheDev]

Nope haven't used yet in any of my projects. But when something is really really local to a specific composable then you may use remember.

[Nathan Castlehow]

remember is for managing state inside of a composable. You won't (and can't) use remember inside of your view model.

[Nathan Castlehow]

An example is you might have a composable with an expanded state which you don't hold on the view model. Inside of the composable you can then go val isExpanded = remember { mutableStateOf(false)}
This state can then be updated independent of your view model.

Overall what you put inside your view model vs what you keep inside a composable comes down to what it is and what architecture you are going for.

[Nathan Castlehow]

https://developer.android.com/jetpack/compose/state is a good article.

[John Aoussou]

@Nathan Castlehow Thanks Nathan, I read the article. I guess what I am trying to understand is whether there are cases when you would both pass a viewmodel to your composable function, and use remember inside the composable. Is correct to say that you can, but as @nilTheDev menitoned, that would only be for variable that are only changed locally in the composable and are not related to the viewmodel?

[Nathan Castlehow]

Yeah that sounds about right 🙂. For example you might remember a card expanded state inside of a card composable (doesn't have to be but for the sake of this lets say it is) but the data for the card (say an image and a description) would come from my viewmodel.

[Steffen Funke]

@John Aoussou This 5 part series from @Zach Klippenstein (he/him) [MOD] helped me A LOT to deepen my knowledge regarding state, remember, and all the likes

https://dev.to/zachklipp/remember-mutablestateof-a-cheat-sheet-10ma

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

There was a really good talk at ADS that talked about state management and when to use ViewModels too:

https://www.youtube.com/watch?v=rmv2ug-wW4U▾