Inject ViewModel using Dagger 2 + Kotlin + ViewModel

Question

class SlideshowViewModel : ViewModel() {

@Inject lateinit var mediaItemRepository : MediaItemRepository

fun init() {
    What goes here?
}

So I\'m tr

Answer 1

Assuming you have a Repository class that can be injected by Dagger and a MyViewModel class that has a dependency on Repository defined as such:

    class Repository @Inject constructor() {
       ...
    }

    class MyViewModel @Inject constructor(private val repository: Repository) : ViewModel() {
        ...
    }

Now you can create your ViewModelProvider.Factory implementation:

    class MyViewModelFactory @Inject constructor(private val myViewModelProvider: Provider) : ViewModelProvider.Factory {

      @Suppress("UNCHECKED_CAST")
      override fun  create(modelClass: Class): T {
        return myViewModelProvider.get() as T
      }

    }

Dagger setup does not look too complicated:

    @Component(modules = [MyModule::class])
    interface MyComponent {
      fun inject(activity: MainActivity)
    }

    @Module
    abstract class MyModule {
      @Binds
      abstract fun bindsViewModelFactory(factory: MyViewModelFactory): ViewModelProvider.Factory
    }

Here's the activity class (might be fragment as well), where the actual injection takes place:

    class MainActivity : AppCompatActivity() {

      @Inject
      lateinit var factory: ViewModelProvider.Factory
      lateinit var viewModel: MyViewModel

      override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // retrieve the component from application class
        val component = MyApplication.getComponent()
        component.inject(this)

        viewModel = ViewModelProviders.of(this, factory).get(MyViewModel::class.java)
      }

    }