koin + ViewModelでDialogFragmentから値を受け取る

背景

Share data between fragments
をkoin + DialogFragmentに適用したらこんな感じ？

実装

MainActivity.kt

class MainActivity : AppCompatActivity() {
  private val model by viewModel<MainViewModel>()
  private val sharedViewModel by viewModel<MainDialogFragment.SharedViewModel>() // 2

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val binding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
    binding.button.setOnClickListener {
      MainDialogFragment().show(this.supportFragmentManager, MainDialogFragment.TAG)
    }
    this.sharedViewModel.selected.observe(this, Observer { selected -> // 4
      this.model.string.postValue(selected)
    })
  }
}

MainDialogFragment.kt

class MainDialogFragment : DialogFragment() {
  private val sharedViewModel by sharedViewModel<SharedViewModel>() // 3

  override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
    val binding = DataBindingUtil.inflate<FragmentMainDialogBinding>(inflater, R.layout.fragment_main_dialog, container, false)
    binding.buttonDone.setOnClickListener {
      this.sharedViewModel.selected.postValue(binding.editText.text.toString()) // 5
      this.dismiss()
    }
    return binding.root
  }

  class SharedViewModel : ViewModel() { // 1
    val selected = MutableLiveData<String>()
  }
}

1. SharedViewModelはDialogFragmentの持ち物とする
2. Activity（DialogFragmentを表示する）側：ViewModelをinject
3. DialogFragment側：sharedViewModelでActivityと共有されたViewModelをinject
4. Activity側：DialogFragmentでの変更を待ち受ける
5. DialogFragment側：postValueで変更を伝える