How can I use constructor injection for ViewModel with Dagger2 android?

Question

I want to use ViewModel with Dagger2 but I don't know how to use constructor injection with ViewModelProviders or ViewModelProvider.Factory

How can I use ViewModel with constructor injection? Should I use ViewModelProvider.Factory or ViewModelProviders?

Update: You can find the solution with details in this link

Answer 1

You can create your own custom class extending ViewModelProvider.Factory

class ViewModelFactory @Inject constructor(
private val providers: @JvmSuppressWildcards Map<Class<out ViewModel>, Provider<ViewModel>>
) : ViewModelProvider.Factory {

override fun <T : ViewModel> create(modelClass: Class<T>): T {
    var provider = providers[modelClass]
    if (provider == null) {
        for ((key, value) in providers) {
            if (modelClass.isAssignableFrom(key)) {
                provider = value
                break
            }
        }
    }
    if (provider == null) {
        throw IllegalStateException("unknown model class $modelClass")
    }

    return provider.get() as T
  }
}

Create module for this class and inject the module in your ApplicationComponent class

@Module
abstract class ViewModelFactoryModule {
   @Binds
   abstract fun bindViewModelFactory(viewModelFactory: ViewModelFactory): ViewModelProvider.Factory
}

Then inside your fragment inject this factory

@Inject
lateinit var factory: ViewModelProvider.Factory

and initialize your viewModel like this

val vm: YourViewModel by viewModels { factory }