MVVM with Databinding and Google's new ViewModel. UA Mobile 2017.
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The document discusses the architecture components in Android, including ViewModel, LiveData, Room, and data binding. It provides an overview of how these components work together in the recommended architecture, how to implement them, common use cases, and answers questions about issues like configuration changes, communication between fragments, and observing data from the ViewModel.
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MVVM with Databinding and Google's new ViewModel. UA Mobile 2017.
- 1. #UAMOBILE ViewMODEL & MVVM & databinding architecture components in ACTION @PreusslerBerlin
- 5. in new suggested architecture
- 6. in new suggested architecture
- 7. In architecture components •A ViewModel provides the data for a specific UI •The ViewModel does not know about the View! •Survives configuration change
- 8. In architecture components •A ViewModel provides the data for a specific UI •The ViewModel does not know about the View! •Survives configuration change
- 9. In architecture components •A ViewModel provides the data for a specific UI •The ViewModel does not know about the View! •Survives configuration change
- 10. In architecture components •A ViewModel provides the data for a specific UI •The ViewModel does not know about the View! •Survives configuration change
- 14. How to use implementation 'android.arch.lifecycle:extensions:1.0.0’ kapt 'android.arch.lifecycle:compiler:1.0.0’
- 15. How to use class MyViewModel() : ViewModel() {
- 16. How to use class MyViewModel(app: Application) : AndroidViewModel(app) {
- 17. How to use override fun onCreate(...) { model = ViewModelProviders .of(this) .get(MyViewModel::class.java) }
- 19. How to use class MyViewModelFactory :ViewModelProvider.Factory(useCase: MyUseCase) { fun <T: ViewModel> create(aClass: Class<T>): T { return MyViewModel(useCase) as T } }
- 20. How to use ViewModelProviders .of(this, MyViewModelFactory(usecase)) .get(MyShowsViewModel::class.java)
- 23. How to use override fun onStopped() { … } No more life cycle forwarding!
- 25. What if… class MyViewModel() : ViewModel() { override fun onCleared() { super.onCleared() cleanupSubscriptions() }
- 27. How does it actually work? class HolderFragment extends Fragment { public HolderFragment() { setRetainInstance(true); } …
- 28. How does it actually work? String HOLDER_TAG = "android.arch.lifecycle.state.StateProviderH olderFragment";
- 30. How does it actually work? @Override public void onDestroy() { super.onDestroy(); mViewModelStore.clear(); }
- 31. Can I do it differently? ViewModel is not life cycle aware?
- 34. Tell us more
- 38. W A I T
- 40. result •Fragment and Activity share the same FragmentManager •But implementation uses Activity’s FragmentManager but ChildFragmentManager for Fragments
- 43. Tell us more
- 44. Other uses cases communication layer between activities and fragments or fragments and fragments
- 46. Tell us more
- 49. ViewModel in MVVM world ModelViewModelView View Presenter Model
- 50. ViewModel in MVVM world ModelViewModelView View ViewModel Model
- 51. Is MVP dead?
- 55. Is MVP dead? •Start by putting the ViewModel behind Presenter
- 59. IntroduciNG LIVE DATA class MyViewModel(): ViewModel() { val message = MutableLiveData<String>()
- 60. IntroduciNG LIVE DATA myModel.message.observe( this, Observer { display(it) })
- 62. Databinding!
- 63. Data binding full picture XML ViewModelbind
- 64. Solves the one big android question once and forever who is the view?
- 65. ViewModel in data binding <TextView … android:id="@+id/all_shows_item_title" android:text="@{viewModel.title}" /> <data> <variable name="viewModel" type="com.vmn.playplex.main.allshows.AllShowsViewModel"/> </data>
- 66. ViewModel in data binding <android.support.v7.widget.CardView … android:onClick="@{() -> viewModel.onClicked()}"> <data> <variable name="viewModel" type="com.vmn.playplex.main.allshows.AllShowsViewModel"/> </data>
- 67. How to use class AllShowsViewModel: ViewModelObservable() { var title : CharSequence = ""
- 68. How to use class AllShowsViewModel: ViewModelObservable() { @Bindable var title : CharSequence = "" private set(value) { if (field != value) { field = value notifyPropertyChanged(BR.title) } }
- 69. How to use class AllShowsViewModel: ViewModelObservable() { @Bindable var title by bindable<CharSequence>("") private set Custom property delegate
- 70. How to use class AllShowsFragment : Fragment () { @Inject lateinit var showsViewModel: AllShowsViewModel
- 71. How to use class AllShowsFragment : Fragment () { @Inject lateinit var showsViewModel: AllShowsViewModel override fun onCreateView(…):View? =
- 72. How to use class AllShowsFragment : Fragment () { @Inject lateinit var showsViewModel: AllShowsViewModel override fun onCreateView(…):View? = FragmentShowsBinding.inflate( inflater, container, false).apply { viewModel = showsViewModel }).root
- 73. How to use class AllShowsFragment : Fragment () { @Inject lateinit var showsViewModel: AllShowsViewModel override fun onCreateView(…):View? = FragmentShowsBinding.inflate( inflater, container, false).apply { viewModel = showsViewModel }).root fragment_shows.xml
- 74. How to use class MyViewModel() :ViewModelObservable() { Coming soon Jose Alcérreca, Google https://medium.com/@dpreussler/add-the-new-viewmodel-to-your-mvvm-36bfea86b159
- 75. How do I…
- 76. .. show a toast class SeriesViewModel : Viewmodel() { … @Bindable var error = ObservableField<String>()
- 77. .. show a toast viewModel.error.addOnPropertyChangedCallback( object : OnPropertyChangedCallback() { override fun onPropertyChanged(…) { showToast(viewModel.error.get() } })
- 78. .. show a toast (alternative) <FrameLayout app:showError="@{viewModel.error}"> @BindingAdapter("showError") fun ViewGroup.onErrorAppeared(error: String?){ errorString?.let { showToast(context, error)) } }
- 79. Data binding full picture XML Activity ViewModel(un)bind bind Life cycle aware class (un)bind
- 80. WAYS TO OBSERVE DATA from VM? •Data binding Observable from xml or code, might need unregister •RxJava Observable from code, needs unregister •LiveData Observable, from code, no unregister, life cycle aware
- 82. Want to know more • https://medium.com/@dpreussler/add-the-new- viewmodel-to-your-mvvm-36bfea86b159 • https://proandroiddev.com/customizing-the-new- viewmodel-cf28b8a7c5fc • http://hannesdorfmann.com/android/arch-components- purist • https://blog.stylingandroid.com/architecture-components- viewmodel/ • https://www.youtube.com/watch?v=QrbhPcbZv0I • https://www.youtube.com/watch?v=c9-057jC1ZA
- 84. viacom.tech
- 87. all problems solved? ViewModels provide a convenient way to retain data across configuration changes but they are not persisted if the application is killed by the operating system https://developer.android.com/topic/libraries/architecture/viewmodel.html#viewm odel_vs_savedinstancestate
- 88. but but WHY?
- 94. but but EditText might have restored it’s state but the ViewModel will not now about it
- 96. store the UI state In Bundles!
- 98. store the UI state The ViewModel
- 99. store the UI state
- 100. lets tweak it class MyModelFactory(val bundle: Bundle?) :ViewModelProvider.Factory() { … fun <T: ViewModel> create(aClass: Class<T>): T { return MyViewModel().apply { readFrom(bundle) } as T } ...
- 101. lets tweak it override onSaveInstanceState(bundle: Bundle){ super.onSaveInstanceState(bundle); viewModel.writeTo(bundle); }