How to sharing viewmodel between an activity and each navgraph destination

[mikucat0309]

I already read this document, but it only talks about sharing between destination, in other word, how to get same viewmodel under same acitivity, no matter whether in composable function or navgraph destination.

BTW, koinNavGraphViewModel can not work with Jetpack Compose, since it doesn't need fragments.

[mikucat0309]

@Composable
inline fun <reified T : ViewModel> getActivityViewModel(): T =
    getViewModel(owner = LocalContext.current as ComponentActivity)

[PGautam27]

One of the best alternative to tackle this problem is to use dagger hilt. Which is splendid, as hiltViewModel would take care of this problem. It doesn't matter whether it's a navgraph or in some composables. I'll add the dependencies and a sample code below.

Add this in the plugin in gradle

plugins {
    ....
    id 'kotlin-kapt'
    id 'dagger.hilt.android.plugin'
}

Add this as a dependency

dependencies {
    //Dagger - Hilt
    implementation "com.google.dagger:hilt-android:2.38.1"
    kapt "com.google.dagger:hilt-android-compiler:2.37"
    implementation "androidx.hilt:hilt-lifecycle-viewmodel:1.0.0-alpha03"
    kapt "androidx.hilt:hilt-compiler:1.0.0"
    implementation 'androidx.hilt:hilt-navigation-compose:1.0.0-alpha03'` 
}

Add this to your classpath

dependencies{
       classpath "com.google.dagger:hilt-android-gradle-plugin:2.38.1"
}

Once the you've successfully added this to your gradle files. Then in your composables use these

@Composable
fun compScreen(
    viewModel: ComplViewModel = hiltViewModel()
) {
   //your functions
}

now the viewModel is directly injected to your composable. I hope this helps you.

Happy coding!!

[mikucat0309]

@PGautam27 Your answer should not work, NavHost provides last NavBackStackEntry as ViewModelStoreOwner.

https://github.com/androidx/androidx/blob/2bbe1a293edea26f8af9a8c9dc490e70207d62af/navigation/navigation-compose/src/main/java/androidx/navigation/compose/NavHost.kt#L162-L164

That is, ViewModels in destination bind to each destination, not NavGraph, NavHost or Activity, ViewModels get in destination will not equal to ones get in Activity, sharing ViewModel between destination also not work.

[PGautam27]

I totally agree to this fact. Here since we are using hiltviewnodel(). We are injecting the viewmodle and not sharing them.

[PGautam27]

You could check upto Philip lackner videos from youtube if you are free. I already said. It's just an alternative of doing. And not the exact solution.