How to instance a ViewModel class automatically with Hilt when I use Compose?

Issue

The Code A is from the end branch of the official sample project.

The project use Hilt to implement dependency injection.

In my mind, I needn't to instance a ViewModel class manually when I use Hilt, and the system will automatically instance a ViewModel when it needs.

But It seems that the author use the code viewModel: MainViewModel = viewModel() to instance the ViewModel class manually in Code A， how can I instance a ViewMode class automatically with Hilt when I use Compose?

Code A

@OptIn(ExperimentalMaterialApi::class)
@Composable
fun CraneHomeContent(
    onExploreItemClicked: OnExploreItemClicked,
    openDrawer: () -> Unit,
    modifier: Modifier = Modifier,
    viewModel: MainViewModel = viewModel(),
) {
    ...
}



@HiltViewModel
class MainViewModel @Inject constructor(
    private val destinationsRepository: DestinationsRepository,
    @DefaultDispatcher private val defaultDispatcher: CoroutineDispatcher
) : ViewModel() {

   ...
}

Solution

As stated in the documentation

The viewModel() function mentioned in the ViewModel section automatically uses the ViewModel that Hilt constructs with the @HiltViewModel annotation. We've provided documentation with information about Hilt's ViewModel integration.

So as long as your viewmodel has the @HiltViewModel annotation, you don’t have to change anything.

Answered By - Karim0x1