Viewmodel Scoped to Compose

ComposeScopedViewModelProvider.kt

import android.os.Bundle
import androidx.compose.runtime.Composable
import androidx.compose.runtime.RememberObserver
import androidx.compose.runtime.remember
import androidx.lifecycle.*
import androidx.lifecycle.viewmodel.CreationExtras
import androidx.lifecycle.viewmodel.MutableCreationExtras
import androidx.lifecycle.viewmodel.compose.LocalViewModelStoreOwner
import androidx.lifecycle.viewmodel.compose.viewModel


//This is creating using help from,Thanks for that
//https://gist.github.com/manuelvicnt/a2e4c4812243ac1b218b24d0ac8d22bb#file-provideviewmodels-kt

//This works with hilt

// This is a way to scope ViewModels to the Composition.
// However, this doesn't survive configuration changes or procress death on its own.
// You can handle all config changes in compose by making the activity handle those in the Manifest file
// e.g. android:configChanges="colorMode|density|fontScale|keyboard|keyboardHidden|layoutDirection|locale|mcc|mnc|navigation|orientation|screenLayout|screenSize|smallestScreenSize|touchscreen|uiMode">


@Composable
public inline fun <reified VM : ViewModel> ComposeScopedViewModelProvider(
    key: String? = null,
    extraParams: Bundle? = null
): VM {
    val originalViewModelStoreOwner = checkNotNull(LocalViewModelStoreOwner.current) {
        "No ViewModelStoreOwner was provided via LocalViewModelStoreOwner"
    }
    val composeViewModelStoreOwner =
        remember() {
            CompositionScopedViewModelStoreOwner(
                originalViewModelStoreOwner as HasDefaultViewModelProviderFactory,
                extraParams
            )
        }
    return viewModel(viewModelStoreOwner = composeViewModelStoreOwner, key = key)
}


class CompositionScopedViewModelStoreOwner(
    private val originalFactoryProvider: HasDefaultViewModelProviderFactory,
    private val extraParams: Bundle?
) :
    ViewModelStoreOwner, RememberObserver, HasDefaultViewModelProviderFactory {


    private val viewModelStoreNew = ViewModelStore()


    override val viewModelStore: ViewModelStore = viewModelStoreNew

    override fun onAbandoned() {
        viewModelStore.clear()
    }

    override fun onForgotten() {
        viewModelStore.clear()
    }

    override fun onRemembered() {
        // Nothing to do here
    }


    override val defaultViewModelCreationExtras: CreationExtras =
        MutableCreationExtras(originalFactoryProvider.defaultViewModelCreationExtras).apply {
            val bundle = Bundle()
            get(DEFAULT_ARGS_KEY)?.let {
                bundle.putAll(it)
            }
            extraParams?.let {
                bundle.putAll(it)
            }
            set(DEFAULT_ARGS_KEY, bundle)
        }

    override val defaultViewModelProviderFactory: ViewModelProvider.Factory
        get() = originalFactoryProvider.defaultViewModelProviderFactory


}

Example.kt

@Composable
fun ExampleCompose(
    modifier: Modifier = Modifier
) {
    val mcqViewModel: TestViewModel = ComposeScopedViewModelProvider()
    
    //or
    
     val viewModel:  TestViewModel = ComposeScopedViewModelProvider(
        key = id,
        extraParams = Bundle().apply {
            putString(EXTRAS_ID, id)
        }
    )
}

For using it with a hilt I added HiltViewModelFactory, otherwise, I had a crash:

@Composable
public inline fun <reified VM : ViewModel> ComposeScopedViewModelProvider(
    key: String? = null,
    extraParams: Bundle? = null
): VM {
    val originalViewModelStoreOwner = checkNotNull(LocalViewModelStoreOwner.current) {
        "No ViewModelStoreOwner was provided via LocalViewModelStoreOwner"
    }
    val composeViewModelStoreOwner =
        remember() {
            CompositionScopedViewModelStoreOwner(
                originalViewModelStoreOwner as HasDefaultViewModelProviderFactory,
                extraParams
            )
        }
    val factory = HiltViewModelFactory(
        context = LocalContext.current,
        navBackStackEntry = originalViewModelStoreOwner as NavBackStackEntry,
    )
    return viewModel(viewModelStoreOwner = composeViewModelStoreOwner, key = key, factory = factory)
}

Yeah , I don't use Compose -navigation, just compose and Hilt , that's why it forced u to handle NavBackStackEntry

But i will suggest just implement it , in CompositionScopedViewModelStoreOwner file the same was i have implemented
ViewModelStoreOwner, RememberObserver, HasDefaultViewModelProviderFactory.

Also , i have fixed a bug related to extra_param for case when parent ViewModel had empty savedStateHandler

Also, on the original link
https://gist.github.com/manuelvicnt/a2e4c4812243ac1b218b24d0ac8d22bb#file-provideviewmodels-kt
Someone has added a way to survive conf changes as well and it looks promising