How to reset view models?

[ivnsch]

Hi,

I added functionality to restore local database backups (sqldelight).

When restoring, I close the old db driver, re-create it.. but the viewmodels are likely keeping a reference to the old db alive, via observers, e.g:

  init {
        viewModelScope.launch {
            milestonesDao.milestone(milestoneId)
                .mapLeft { it.toUiError() }
                .collectHandling(_error) {
                    _milestone.value = toUiMilestone(it)
                }
        }
}

with dao:

private val milestoneQueries get() = database.milestoneQueries
override fun milestone(id: MilestoneId): Flow<Either<FetchMilestoneDaoError, Milestone>> = ...

java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase: /data/user/0/foo/databases/db.db), msg: UiErrorMsg(msg=Unknown error, debugInfos=java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase: /data/user/0/foo/databases/db.db)

So I figured, I'd like to tear down and recreate all the view models? but not succeeding so far.

I defined a scope

scope(named("viewmodels")) { .. }

and then

koin.getScopeOrNull("viewmodels")?.close()

but e.g. this on viewmodels is never called

override fun onCleared() {
    super.onCleared()
    log.w { "viewmodel cleared: ${this.hashCode()}" }
}

and error persists.

there's also e.g.

(koin.get<Activity>() as? MainActivity)?.viewModelStore?.clear()

but not sure this is what I should use and how to combine with the view models management by koin?

Maybe I'm entirely off track and I need a different approach to solve this, any advice appreciated!

[samyak2403]

To "reset" ViewModels in Koin after a major data event like a database restoration, I'd suggest these two approaches:

Approach A: Reactive UI (Preferred)

If your Repository exposes data as a Flow or LiveData directly from Room, you typically don't need to reset the ViewModel. Room's invalidation tracker will automatically emit the new data to the Flow as soon as the database is updated, and your ViewModel will reflect the change instantly.

Approach B: Custom Koin Scopes

If you need to force-recreate the ViewModel instances, you can define them within a custom Koin Scope. This allows you to close and re-open the scope, which wipes the cached instances.

Approach 1: Define the Scope

val myModule = module {
    scope<MySessionScope> {
        viewModel { MyViewModel(get()) }
    }
}

Approach 2: Reset Logic
When the restore is complete, close the existing scope. The next time you call getScope(), a fresh ViewModel will be injected.

getKoin().getScopeOrNull("session_id")?.close()
val newScope = getKoin().createScope("session_id", named<MySessionScope>())