Assisted Injection with Hilt in Jetpack Compose multi module app

Question

I am having some trouble with assisted Injection in Hilt and Jetpack Compose. I have set stuff up like here https://medium.com/scalereal/providing-assistedinject-supported-viewmodel-for-composable-using-hilt-ae973632e29a

Just for the sake of it... Code look like this:

ViewModel Implementation. The ViewModel is in the "feature" module:

class NoteDetailViewModel @AssistedInject constructor(
    @Assisted private val noteId: String,
    private val notyTaskManager: NotyTaskManager,
    private val noteRepository: NotyNoteRepository
) : ViewModel() {
  
    // Other ViewModel's implementation...
  
    @AssistedFactory
    interface Factory {
        fun create(noteId: String): NoteDetailViewModel
    }

    @Suppress("UNCHECKED_CAST")
    companion object {
        fun provideFactory(
            assistedFactory: Factory,
            noteId: String
        ): ViewModelProvider.Factory = object : ViewModelProvider.Factory {
            override fun <T : ViewModel?> create(modelClass: Class<T>): T {
                return assistedFactory.create(noteId) as T
            }
        }
    }
}

@Module
@InstallIn(ActivityRetainedComponent::class)
interface AssistedInjectModule

Then, in the MainActivity, which is the only Activity in the app anyway (app module):

@AndroidEntryPoint
class MainActivity : AppCompatActivity() {

    @EntryPoint
    @InstallIn(ActivityComponent::class)
    interface ViewModelFactoryProvider {
        fun noteDetailViewModelFactory(): NoteDetailViewModel.Factory
    }
    ...

And lastly, the @Composable looks like this (located in the feature module):

@Composable
fun noteDetailViewModel(noteId: String): NoteDetailViewModel {
    val factory = EntryPointAccessors.fromActivity(
        LocalContext.current as Activity,
        MainActivity.ViewModelFactoryProvider::class.java
    ).noteDetailViewModelFactory()

    return viewModel(factory = NoteDetailViewModel.provideFactory(factory, noteId))
}

Can anybody help? Thanks!

There's a couple of problems: Firstly, the MainActivity.ViewModelFactoryProvider::class.java is not accessible in the feature module. Obviously you can't create a circular reference. That's why I tried replacing it with NoteDetailViewModel.Factory; it should be the same, right? Unfortunately I get an error saying "cannot cast from Singleton_C to NoteDetailViewModel".

Putting the Composable function in the MainActivity file might also be a solution, but that doesn't work either, obviously...

I solved it another way in the end, using an Annotation class. It works, but I'd like to use the assisted injection.

Assisted Injection with Hilt in Jetpack Compose multi module app

0 Answers0