Since Composables will eventually replace Fragment...

# compose

[Brady Aiello]

Since Composables will eventually replace Fragments, I was wondering if we'll be able to scope ViewModels to Composables, or Composable destinations within Compose Navigation? Keeping lots of ViewModels all scoped to a single Activity, or keeping one god-ViewModel would both hold data for every page in memory concurrently, and that seems like a bad idea. Am I wrong, or is there another strategy the Compose folks are considering?

[Adam Powell]

see the other thread above regarding replace or not; that's up to you

[Adam Powell]

if you're using all-compose, there's no reason to leave activity recreation for configuration changes enabled since compose knows how to handle them at a much finer granularity

[Adam Powell]

which then means the arch components ViewModel superclass doesn't serve much purpose; any old object you remember {} persists as normal

[Adam Powell]

we have the savedInstanceState APIs in compose already for saving across process restarts, and that doesn't experience the same ViewModel scoping questions

[Adam Powell]

that's the long term

[Adam Powell]

in the short term, I believe the navigation team is closer to the AAC ViewModel scope provider APIs and they intend to use them for navigation destinations - I might be out of date on this 🙂

[Adam Powell]

so yes, scoping ViewModels for situations where you have to keep activity recreation for compatibility with other parts of your code will be possible. I haven't kept up with the current state of the art on this at the moment

[Brady Aiello]

You disable activity recreation for any configuration changes? I wasn't aware this was the recommended practice for pure Compose apps. If we ignore config changes, will Compose still act appropriately with locale or dark theme changes for instance? Gonna test this out tomorrow.

[Shakil Karim]

I hope we can eliminate ViewModel and fragments in Compose only app, that would simplify things so much.

[Brady Aiello]

Thanks, Adam! When you say the savedInstanceState APIs, you mean these? https://developer.android.com/jetpack/compose/interop#savedinstancestate

[Brady Aiello]

Okay, cool. Thank you! 🎄

[Ian Lake]

Navigation already scopes ViewModels to individual destinations and had since it's first alpha 😃