[AssistedInject] Integration with @HiltViewModel

It’d be nice to have Assisted Injection support for Hilt ViewModels.

A nice API would be something like the following:

@HiltViewModel
class PlantDetailViewModel @AssistedInject constructor(
    savedStateHandle: SavedStateHandle,
    plantRepository: PlantRepository,
    @Assisted private val plantId: String
) : ViewModel() { ... }

@AssistedFactory
interface PlantDetailViewModelFactory {
    fun create(plantId: String): PlantDetailViewModel
}

And use it from the View like:

@AndroidEntryPoint
class PlantDetailFragment : Fragment() {

    private val args: PlantDetailFragmentArgs by navArgs()

    @Inject
    lateinit var plantDetailViewModelFactory: PlantDetailViewModelFactory

    private val plantDetailViewModel: PlantDetailViewModel by viewModels {
        plantDetailViewModelFactory.create(args.plantId)
    }
}

[bompf]

This absolutely should be supported. Injecting ViewModels/Presenters is one of the primary use cases of AssistedInjection on Android.

[tfcporciuncula]

@wbervoets With the new @HiltViewModel you can have the SavedStateHandle as a dependency without having to annotate it with @Assisted. The SavedStateHandle is now a binding from the new ViewModelComponent, so it doesn’t need to be assist-injected anymore.