i have a fragment in my app that i show two list of saparate data in it.i'm using from android architecture components to load my data.
Once the data is fetched from the network, I store it locally using Room DB and then display it on the UI using ViewModel that observes on the LiveData object (this works fine). However, I want to be able to have a refreshLayout which When Refreshing Occurs a refresh action and perform a network request to get new data from the API if and only if there is a network connection.The issue is when Refreshing Occurs data load from locate database and network together .
my question is :How do I manage to get data only from Network when refreshing data?
How do I manage to get data only from Network when refreshing data?
I've seen this question and it didn't help me...
my codes:
repository:
public NetworkResult<LiveData<HomeHealthModel>> getHomeHealth(String query) {
MutableLiveData<String> _liveError = new MutableLiveData<>();
MutableLiveData<HomeHealthModel> data = new MutableLiveData<>();
LiveData<List<GeneralItemModel>> liveClinics = App.getDatabase().getGeneralItemDAO().getTops(GeneralItemType.Clinics, GeneralItemType.TOP);
LiveData<List<GeneralItemModel>> liveDoctors = App.getDatabase().getGeneralItemDAO().getTops(GeneralItemType.Doctors, GeneralItemType.TOP);
setupService(_liveError); //request data from network
data.postValue(new HomeHealthModel(liveClinics, liveDoctors));
_liveError.postValue(String.valueOf(NetworkResponseType.LocaleData));
return new NetworkResult<>(_liveError, data);
}
my viewModel
public class HomeHealthVM extends ViewModel {
private MutableLiveData<String> queryLiveData;
private LiveData<String> networkErrors;
private LiveData<List<GeneralItemModel>> Clinics;
private LiveData<List<GeneralItemModel>> Doctors;
public HomeHealthVM(HealthRepository repository) {
queryLiveData = new MutableLiveData<>();
LiveData<NetworkResult<LiveData<HomeHealthModel>>> repoResult;
repoResult = Transformations.map(queryLiveData, repository::getHomeHealth);
LiveData<HomeHealthModel> model = Transformations.switchMap(repoResult, input -> input.data);
Doctors = Transformations.switchMap(model, HomeHealthModel::getDoctors);
Clinics = Transformations.switchMap(model, HomeHealthModel::getClinics);
networkErrors = Transformations.switchMap(repoResult, input -> input.error);
}
public void search(String queryString) {
queryLiveData.postValue(queryString);
}
public String lastQueryValue() {
return queryLiveData.getValue();
}
public LiveData<String> getNetworkErrors() {
return networkErrors;
}
public LiveData<List<GeneralItemModel>> getClinics() {
return Clinics;
}
public LiveData<List<GeneralItemModel>> getDoctors() {
return Doctors;
}
}
my fragment code:
private void setupViewModel() {
ViewModelFactory<HealthRepository> factory = new ViewModelFactory<>(new HealthRepository());
healthVM = ViewModelProviders.of(this, factory).get(HomeHealthVM.class);
healthVM.getNetworkErrors().observe(this, states -> {
try {
if (Integer.parseInt(states) != WarningDialogType.Success &&
Integer.parseInt(states) != WarningDialogType.Locale) {
stopLoading();
linerNoInternet.setVisibility(View.VISIBLE);
linerContent.setVisibility(View.GONE);
}
} catch (Exception e) {
stopLoading();
linerNoInternet.setVisibility(View.VISIBLE);
linerContent.setVisibility(View.GONE);
}
});
healthVM.getDoctors().observe(this, doctors -> {
if (doctors.size() > 0) {
doctorsAdapter.submitList(doctors);
stopLoading();
} else {
}
});
healthVM.getClinics().observe(this, clinics -> {
if (clinics.size() > 0) {
clinicsAdapter.submitList(clinics);
stopLoading();
} else {
conesClinics.setVisibility(View.GONE);
}
});
healthVM.search("");
}
I want to create change password option for my app which will update the current password with new pasword and Im using rxjava and retrofit to send a update request to server. Sorry if Im having issues with the correct terminologies. Im new to android. Issue im having is Validations I have added to viewmodel does not work properly. I think its because of the fragment class not configured properly. im having trouble with setting it to to show error messages(such as "Old Password is required" and "New Password is required") which should be validated by the viewmodel and change password according to that.
Im currently getting a "cannot resolve method maketext" error from the Toast I have made in the fragment class.
Any help with this matter is highly appreciated.Please find my code here. Also please let me know if my approach is correct or how it can be improved.
UpdatePasswordFragment.java
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mViewModel = ViewModelProviders.of(this).get(UpdatePasswordViewModel.class);
binding.setViewModel(mViewModel);
//mViewModel.setUser(new Gson().fromJson(getIntent().getStringExtra(Constants.INTENT_USER), User.class));
mViewModel.setUser(new Gson().fromJson(getArguments().getString("user"), User.class));
binding.setLifecycleOwner(this);
mViewModel.getMessage().observe(this, s -> {
Toast.makeText(this,s, Toast.LENGTH_LONG).show();
});
}
UpdatePassowrdViewModel.java
public class UpdatePasswordViewModel extends ViewModel {
private Repository Repository;
Application application;
public void init(Application application) {
this.application = application;
showSpinner.setValue(false);
Repository = new Repository(application);
updatePasswordMutableLiveData.setValue(new UpdatePassword());
}
private MutableLiveData<UpdatePassword> updatePasswordMutableLiveData = new MutableLiveData<>();
private MutableLiveData<Boolean> showSpinner = new MutableLiveData<>();
private final String SUCCESS_MESSAGE = "Password Successfully Changed";
private User mUser;
public MutableLiveData<String> getOldPassword() {
return oldPassword;
}
public void setOldPassword(MutableLiveData<String> oldPassword) {
this.oldPassword = oldPassword;
}
public MutableLiveData<String> getNewPassword() {
return newPassword;
}
public void setNewPassword(MutableLiveData<String> newPassword) {
this.newPassword = newPassword;
}
public MutableLiveData<String> getConfirmNewPassword() {
return confirmNewPassword;
}
public void setConfirmNewPassword(MutableLiveData<String> confirmNewPassword) {
this.confirmNewPassword = confirmNewPassword;
}
private MutableLiveData<String> oldPassword = new MutableLiveData<>();
private MutableLiveData<String> newPassword = new MutableLiveData<>();
private MutableLiveData<String> confirmNewPassword = new MutableLiveData<>();
private MutableLiveData<Boolean> showLoader = new MutableLiveData<>();
public void setUser(User user) {
this.mUser = user;
}
public MutableLiveData<String> getMessage() {
return message;
}
private MutableLiveData<String> message = new MutableLiveData<>();
public MutableLiveData<Boolean> getShowLoader() {
return showLoader;
}
#SuppressLint("CheckResult")
public void changePassword() {
showSpinner.setValue(true);
Repository.changePassword(mUser.getUserName(), oldPassword.getValue(),newPassword.getValue())
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(s -> {
if(SUCCESS_MESSAGE.equals(s)) {
oldPassword.setValue("");
newPassword.setValue("");
confirmNewPassword.setValue("");
}
showSpinner.setValue(false);
message.setValue(s.toString());
}, throwable -> {
showSpinner.setValue(false);
message.setValue(throwable.getLocalizedMessage());
});
}
public void savePasswordClicked(View view) {
if(oldPassword.getValue().trim().length() == 0) {
message.setValue("Old Password is required");
return;
}
if(newPassword.getValue().trim().length() == 0) {
message.setValue("New Password is required");
return;
}
if(!newPassword.getValue().equals(confirmNewPassword.getValue())) {
message.setValue("New Password and Confirm Password doesn't match");
return;
}
changePassword();
}
Repository.Java
public Observable<ApiResponse<User>> changePassword(String userId, String oldPassword, String newPassword) {
// return mApi.updatePassword(UpdatePassword);
return mApi.updatePassword(userId,oldPassword, newPassword );
}
THis is the retrofit call I have made in the APi
#PUT("user/updatepassword")
Observable<ApiResponse<User>> updatePassword(
#Field("currentPassword") String oldPassword,
#Field("newPassword") String newPassword,
#Field("userId") String userId
);
First of all, you are using not only ViewModel here, but data binding too. First thing you need to do to be able to use data binding is to add to your build.gradle the following:
// enable data binding for app here
android {
...
dataBinding {
enabled = true
}
}
Second mistake is that you are making setters and getters for MutableLiveData, you should change the value of the data by calling .setValue(newValue), the reference of the object should be immutable if you want your observers to be notified of change.
The last thing you need to do is to make sure the required fields are binded correctly in you layout, in your case you need a two-way binding, example:
<CheckBox
android:id="#+id/rememberMeCheckBox"
android:checked="#={viewmodel.rememberMe}"
/>
You can read more about two-way data binding here.
I'm new in RxJava. I have currently executed three API calls parallel which is independent of each other via Retrofit using Single.Zip Operator. On getting a successful response of all three API calls, I have to insert the data from all three APIs into Room database into Different entities which takes 20 seconds.
So I need to execute database operations inside Single.Zip operator. Because the logic is written inside onSuccess method running away before Database Operation performed.
I have tried to take separate Observer for performing database operation but didn't work.
public void callOfflineDataAPIs() {
setIsLoading(true);
Single<BaseResponse<ProductResponse>> single1 = getDataManager().getOfflineProductListApiCall(getDataManager().getLastTimeStampOfflineProductCall()).subscribeOn(getSchedulerProvider().io()).observeOn(getSchedulerProvider().ui());
Single<BaseResponse<LocationResponse>> single2 = getDataManager().getOfflineLocationListApiCall(getDataManager().getLastTimeStampOfflineLocationCall()).subscribeOn(getSchedulerProvider().io()).observeOn(getSchedulerProvider().ui());
Single<BaseResponse<OfflineMasterData>> single3 = getDataManager().getOfflineMasterDataListApiCall(getDataManager().getLastTimeStampOfflineMasterCall()).subscribeOn(getSchedulerProvider().io()).observeOn(getSchedulerProvider().ui());
DisposableSingleObserver<List<Boolean>> result = Single.zip(single3, single1, single2,
(offlineMasterDataBaseResponse, productResponseBaseResponse, locationResponseBaseResponse) -> {
List<Boolean> apiCalls = new ArrayList<>();
apiCalls.add(masterDataCRUDOperation(offlineMasterDataBaseResponse));
apiCalls.add(productDataCRUDOperation(productResponseBaseResponse));
apiCalls.add(locationDataCRUDOperation(locationResponseBaseResponse));
return apiCalls;
}).subscribeOn(getSchedulerProvider().io()).observeOn(getSchedulerProvider().ui()).subscribeWith(new DisposableSingleObserver<List<Boolean>>() {
#Override
public void onSuccess(List<Boolean> apiCalls) {
setIsLoading(false);
LogHelper.e(TAG, "DisposableSingleObserver- onSuccess");
boolean isSync = true;
for (int i = 0; i < apiCalls.size(); i++) {
if (!apiCalls.get(i)) {
isSync = false;
LogHelper.e(TAG, "DisposableSingleObserver- onSuccess- apiCalls.get(i)", i);
callOfflineDataAPIs();
break;
}
}
if (isSync) {
LogHelper.e(TAG, "IF-isSync");
if (BuildConfig.IS_CLIENT_BUILD) {
LogHelper.e(TAG, "IF-isSync-IS_CLIENT_BUILD-true");
getDataManager().setCurrentWarehouseKey(1);
getNavigator().onGoButtonClick();
} else {
LogHelper.e(TAG, "ELSE-isSync-IS_CLIENT_BUILD-false");
getWarehouseList();
}
}
}
#Override
public void onError(Throwable e) {
LogHelper.e(TAG, "DisposableSingleObserver- Throwable");
setIsLoading(false);
String errorMessage = new NetworkError(e).getAppErrorMessage();
getNavigator().exitApplicationOnError(errorMessage);
}
});
}
Logic written inside onSuccess Method execute once all DB Operation performed.
You can modify your code to something like:
DisposableSingleObserver<List<Boolean>> result = Single.zip(single3, single1, single2,
(offlineMasterDataBaseResponse, productResponseBaseResponse, locationResponseBaseResponse) -> {
List<Boolean> apiCalls = new ArrayList<>();
apiCalls.add(masterDataCRUDOperation(offlineMasterDataBaseResponse));
apiCalls.add(productDataCRUDOperation(productResponseBaseResponse));
apiCalls.add(locationDataCRUDOperation(locationResponseBaseResponse));
return apiCalls;
}).subscribeOn(getSchedulerProvider().io())
.map(new Function<List<Boolean> apiCalls, List<Boolean> apiCalls>() {
#Override
public List<Boolean> apiCalls apply(List<Boolean> apiCalls) throws Exception {
// perform database operations here
return apiCalls;
}
})
.observeOn(getSchedulerProvider().ui())
.subscribe(new Observer<List<Boolean>>() {
#Override
public void onNext(User user) {
// Do something
}
#Override
public void onError(Throwable e) {
// Do something
}
#Override
public void onComplete() {
// Do something
}
});
In my app i am using android MVVM architecture, so for retrieving data from cloud firestore i am using layers so i create one more class (FirebaseQueryLiveData) for getting result from firestore. So with my code i am getting the realtime update but not able to add the Cache Source feature of firestore.I want to enable offline mode by adding cache soure. How to add it.
ProductViewModel.java
public class ProductViewModel extends AndroidViewModel {
private FirebaseFirestore db = FirebaseFirestore.getInstance();
private MediatorLiveData<List<ProductModel>> productListLiveData;
private FirebaseQueryLiveData liveData;
public ProductViewModel(#NonNull Application application) {
super(application);
}
public LiveData<List<ProductModel>> getProductList() {
productListLiveData = new MediatorLiveData<>();
completeProductList();
return productListLiveData;
}
private void completeProductList() {
Query query = db.collection("mainCollection").document("productList")
.collection("productCollection");
liveData = new FirebaseQueryLiveData(query);
productListLiveData.addSource(liveData, new Observer<QuerySnapshot>() {
#Override
public void onChanged(QuerySnapshot queryDocumentSnapshots) {
if (queryDocumentSnapshots!= null){
List<ProductModel> productModelList = new ArrayList<>();
for (QueryDocumentSnapshot documentSnapshot : queryDocumentSnapshots){
ProductModel model = documentSnapshot.toObject(ProductModel.class);
productModelList.add(model);
}productListLiveData.setValue(productModelList);
}
}
});
}
FirebaseQueryLiveData.java
public class FirebaseQueryLiveData extends LiveData<QuerySnapshot> {
private MyValueEventListener listener = new MyValueEventListener();
private Query query;
Source source = Source.CACHE;
private boolean listenerRemovePending = false;
private ListenerRegistration registration;
private Handler handler = new Handler();
private final Runnable removeListener = new Runnable() {
#Override
public void run() {
registration.remove();
listenerRemovePending = false;
}
};
public FirebaseQueryLiveData(Query query) {
this.query = query;
}
#Override
protected void onActive() {
super.onActive();
if (listenerRemovePending){
handler.removeCallbacks(removeListener);
}else {
registration= query.addSnapshotListener(listener);
}
listenerRemovePending= false;
}
#Override
protected void onInactive() {
super.onInactive();
handler.postDelayed(removeListener, 2000);
listenerRemovePending=true;
}
private class MyValueEventListener implements EventListener<QuerySnapshot> {
#Override
public void onEvent(#Nullable QuerySnapshot queryDocumentSnapshots, #Nullable FirebaseFirestoreException e) {
setValue(queryDocumentSnapshots);
}
}
}
For Android and iOS, Cloud Firestore has offline persistence enabled by default. This means that your app will work for short to intermediate periods of being disconnected.
And yes, you can specify the source with the help of the DocumentReference.get(Source source) and Query.get(Source source) methods.
By default, get() attempts to provide up-to-date data when possible by waiting for data from the server, but it may return cached data or fail if you are offline and the server cannot be reached. This behavior can be altered via the Source parameter.
So we can now pass as an argument to the DocumentReference or to the Query the source so we can force the retrieval of data from the chache only like this:
FirebaseFirestore db = FirebaseFirestore.getInstance();
DocumentReference docIdRef = db.collection("tests").document("fOpCiqmUjAzjnZimjd5c");
docIdRef.get(Source.CACHE).addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
#Override
public void onSuccess(DocumentSnapshot documentSnapshot) {
//Get data from the documentSnapshot object
}
});
In this case, we force the data to be retrieved from the cache only but why to use this feature when you say that you want to get realtime updates? So for your use-case I don't see why you would get the data from cache.
I am attempting to developed an Android application based on the following talk presented by Jake Wharton
The State of Managing State with RxJava
21 March 2017 – Devoxx (San Jose, CA, USA)
Jake promised a part 2 and/or GITHUB example which I am unable to find (If indeed either exists)
At a high level I can follow/understand the majority of the above talk.
However I have the following questions.
I can see how employing UiEvent, UiModel, Action, and Result keeps concerns separated.
What I am confused about is the following:-
The diagram on slide 194 shows the "flow/stream" of Observables as
Android Device -----> Observable<UiEvent> -----> <application code> -----> Observable<Action> -----> {Backend}
{Backend} -----> Observable<Result> -----> <application code> -----> Observable<UiModel> -----> Android Device
Slide 210 contains this code snippet, showing how the Result(s) stream is "scan"ned into UiModel
SubmitUiModel initialState = SubmitUiModel.idle();
Observable<Result> results = /* ... */;
Observable<SubmitUiModel> uiModels = results.scan(initialState, (state, result) -> {
if (result == CheckNameResult.IN_FLIGHT
|| result == SubmitResult.IN_FLIGHT)
return SubmitUiModel.inProgress();
if (result == CheckNameResult.SUCCESS)
return SubmitUiModel.idle();
if (result == SubmitResult.SUCCESS)
return SubmitUiModel.success();
// TODO handle check name and submit failures...
throw new IllegalArgumentException("Unknown result: " + result);
});
and the final code snippet on slide 215, the code snippet resembles this:-
ObservableTransformer<SubmitAction, SubmitResult> submit =
actions -> actions.flatMap(action -> service.setName(action.name)
.map(response -> SubmitResult.SUCCESS)
.onErrorReturn(t -> SubmitResult.failure(t.getMessage()))
.observeOn(AndroidSchedulers.mainThread())
.startWith(SubmitResult.IN_FLIGHT));
ObservableTransformer<CheckNameAction, CheckNameResult> checkName =
actions -> actions.switchMap(action -> action
.delay(200, MILLISECONDS, AndroidSchedulers.mainThread())
.flatMap(action -> service.checkName(action.name))
.map(response -> CheckNameResult.SUCCESS)
.onErrorReturn(t -> CheckNameResult.failure(t.getMessage()))
.observeOn(AndroidSchedulers.mainThread())
.startWith(CheckNameResult.IN_FLIGHT));
which illustrates conversion from Action(s) to Result(s)
what am I missing from this talk/slide-deck on how to combine the UiEvent/UiModel to the Action/Result stream?
The stream is driven by UiEvents
How do you complete the flow from UiEvent(s) to Action back to Result then finally UiModel?
UPDATE
Using the Star Wars API I have taken the following approach
I use my UI Events to drive the transformation between UI Events to Results via Actions, then scan the results to map back to UI Model.
Heres my classes and code:-
ACTION CLASSES
==============
public abstract class Action<T> {
Api service = Service.instance();
final T data;
public Action(final T data) {
this.data = data;
}
public T getData() {
return data;
}
public abstract Observable<Response<String>> execute();
}
public class CheckCharacterAction extends Action<String> {
public CheckCharacterAction(final String characterName) {
super(characterName);
}
#Override
public Observable<Response<String>> execute() {
return service.peopleSearch(getData());
}
}
public class CheckFilmAction extends Action<String> {
public CheckFilmAction(final String filmTitle) {
super(filmTitle);
}
#Override
public Observable<Response<String>> execute() {
return service.filmSearch(getData());
}
}
public class SearchAction extends Action<String> {
public SearchAction(final String search) {
super(search);
}
#Override
public Observable<Response<String>> execute() {
return service.filmSearch(getData());
}
}
EVENT CLASSES
=============
public abstract class UiEvent<T> {
private final T data;
public UiEvent(final T data) {
this.data = data;
}
public T getData() {
return data;
}
}
public class CharacterUiEvent extends UiEvent<String> {
public CharacterUiEvent(final String name) {
super(name);
}
}
public class FilmUiEvent extends UiEvent<String> {
public FilmUiEvent(final String title) {
super(title);
}
}
public class SearchUiEvent extends UiEvent<String> {
public SearchUiEvent(final String data) {
super(data);
}
}
UI MODEL CLASSES
================
public class UiModel<T> {
public final boolean isProgress;
public final String message;
public final boolean isSuccess;
public T data;
public UiModel(final boolean isProgress) {
this.isProgress = isProgress;
this.message = null;
this.isSuccess = false;
this.data = null;
}
public UiModel(final T data) {
this.isProgress = false;
this.message = null;
this.isSuccess = true;
this.data = data;
}
public UiModel(final String message) {
this.isProgress = false;
this.message = message;
this.isSuccess = false;
this.data = null;
}
public UiModel(final boolean isProgress, final String message, final boolean isSuccess, final T data) {
this.isProgress = isProgress;
this.message = message;
this.isSuccess = isSuccess;
this.data = data;
}
}
public class CharacterUiModel extends UiModel<JsonData> {
public CharacterUiModel(final boolean isProgress) {
super(isProgress);
}
public CharacterUiModel(final JsonData data) {
super(data);
}
public CharacterUiModel(final String message) {
super(message);
}
public CharacterUiModel(final boolean isProgress, final String message, final boolean isSuccess, final JsonData data) {
super(isProgress, message, isSuccess, data);
}
public static CharacterUiModel inProgress() {
return new CharacterUiModel(true);
}
public static CharacterUiModel success(final JsonData data) {
return new CharacterUiModel(data);
}
public static CharacterUiModel failure(final String message) {
return new CharacterUiModel(message);
}
}
public class FilmUiModel extends UiModel<JsonData> {
public FilmUiModel(final boolean isProgress) {
super(isProgress);
}
public FilmUiModel(final JsonData data) {
super(data);
}
public FilmUiModel(final String message) {
super(message);
}
public FilmUiModel(final boolean isProgress, final String message, final boolean isSuccess, final JsonData data) {
super(isProgress, message, isSuccess, data);
}
public static FilmUiModel inProgress() {
return new FilmUiModel(true);
}
public static FilmUiModel success(final JsonData data) {
return new FilmUiModel(data);
}
public static FilmUiModel failure(final String message) {
return new FilmUiModel(message);
}
}
public class SearchUiModel extends UiModel<JsonData> {
private SearchUiModel(final boolean isProgress) {
super(isProgress);
}
private SearchUiModel(final JsonData data) {
super(data);
}
private SearchUiModel(final String message) {
super(message);
}
private SearchUiModel(final boolean isProgress, final String message, final boolean isSuccess, final JsonData data) {
super(isProgress, message, isSuccess, data);
}
public static SearchUiModel idle() {
return new SearchUiModel(false, null, false, null);
}
public static SearchUiModel inProgress() {
return new SearchUiModel(true);
}
public static SearchUiModel success(final JsonData data) {
return new SearchUiModel(data);
}
public static SearchUiModel failure(final String message) {
return new SearchUiModel(message);
}
}
RESULT CLASSES
==============
public abstract class Result<T> {
public enum LIFECYCLE {
DEPARTURE_LOUNGE,
IN_FLIGHT,
LANDED_SAFELY,
CRASHED_BURNED
}
final LIFECYCLE lifecycle;
final T data;
final String errorMessage;
public Result(final LIFECYCLE lifecycle, final T data, final String errorMessage) {
this.lifecycle = lifecycle;
this.data = data;
this.errorMessage = errorMessage;
}
public T getData() {
return data;
}
public String getErrorMessage() {
return errorMessage;
}
public LIFECYCLE getLifecycle() {
return lifecycle;
}
}
public class CharacterResult extends Result<JsonData> {
private CharacterResult(final LIFECYCLE lifecycle, final JsonData data, final String errorMessage) {
super(lifecycle, data, errorMessage);
}
private CharacterResult(final LIFECYCLE lifecycle) {
super(lifecycle, null, null);
}
public static CharacterResult departureLounge() {
return new CharacterResult(LIFECYCLE.DEPARTURE_LOUNGE);
}
public static CharacterResult inflight() {
return new CharacterResult(LIFECYCLE.IN_FLIGHT);
}
public static CharacterResult landedSafely(final JsonData data) {
return new CharacterResult(LIFECYCLE.LANDED_SAFELY, data, null);
}
public static CharacterResult crashedBurned(final String errorMessage) {
return new CharacterResult(LIFECYCLE.CRASHED_BURNED, null, errorMessage);
}
}
public class FilmResult extends Result<JsonData> {
private FilmResult(final LIFECYCLE lifecycle, final JsonData data, final String errorMessage) {
super(lifecycle, data, errorMessage);
}
private FilmResult(final LIFECYCLE lifecycle) {
super(lifecycle, null, null);
}
public static FilmResult departureLounge() {
return new FilmResult(LIFECYCLE.DEPARTURE_LOUNGE);
}
public static FilmResult inflight() {
return new FilmResult(LIFECYCLE.IN_FLIGHT);
}
public static FilmResult landedSafely(final JsonData data) {
return new FilmResult(LIFECYCLE.LANDED_SAFELY, data, null);
}
public static FilmResult crashedBurned(final String errorMessage) {
return new FilmResult(LIFECYCLE.CRASHED_BURNED, null, errorMessage);
}
}
public class SearchResult extends Result<JsonData> {
private SearchResult(final LIFECYCLE lifecycle, final JsonData data, final String errorMessage) {
super(lifecycle, data, errorMessage);
}
private SearchResult(final LIFECYCLE lifecycle) {
super(lifecycle, null, null);
}
public static SearchResult departureLounge() {
return new SearchResult(LIFECYCLE.DEPARTURE_LOUNGE);
}
public static SearchResult inflight() {
return new SearchResult(LIFECYCLE.IN_FLIGHT);
}
public static SearchResult landedSafely(final JsonData data) {
return new SearchResult(LIFECYCLE.LANDED_SAFELY, data, null);
}
public static SearchResult crashedBurned(final String errorMessage) {
return new SearchResult(LIFECYCLE.CRASHED_BURNED, null, errorMessage);
}
}
I then set up my Rx Streams as follows from my Activity onCreate() method:-
final Observable<SearchUiEvent> searchEvents = RxView.clicks(activityMainBinding.searchButton)
.observeOn(AndroidSchedulers.mainThread())
.subscribeOn(AndroidSchedulers.mainThread())
.map(ignored -> new SearchUiEvent(activityMainBinding.filmTitle.getText().toString()));
final Observable<FilmUiEvent> filmEvents = RxTextView.afterTextChangeEvents(activityMainBinding.filmTitle)
.skipInitialValue()
.observeOn(AndroidSchedulers.mainThread())
.subscribeOn(AndroidSchedulers.mainThread())
.delay(1000, MILLISECONDS, AndroidSchedulers.mainThread())
.map(text -> new FilmUiEvent(text.view().getText().toString()));
final Observable<CharacterUiEvent> characterEvents = RxTextView.afterTextChangeEvents(activityMainBinding.people)
.skipInitialValue()
.observeOn(AndroidSchedulers.mainThread())
.subscribeOn(AndroidSchedulers.mainThread())
.delay(200, MILLISECONDS, AndroidSchedulers.mainThread())
.map(text -> new CharacterUiEvent(text.view().getText().toString()));
/**
*
*/
final Observable<UiEvent> uiEvents = Observable.merge(searchEvents, filmEvents, characterEvents);
/*********
*
*/
final ObservableTransformer<SearchUiEvent, SearchResult> searchAction =
events -> events.flatMap(event -> new SearchAction(event.getData()).execute().subscribeOn(Schedulers.io()))
.map(response -> SearchResult.landedSafely(new JsonData(response.body())))
.onErrorReturn(throwable -> SearchResult.crashedBurned(throwable.getMessage()))
.startWith(SearchResult.inflight());
final ObservableTransformer<FilmUiEvent, FilmResult> filmAction =
events -> events.flatMap(event -> new CheckFilmAction(event.getData()).execute().subscribeOn(Schedulers.io()))
.map(response -> FilmResult.landedSafely(new JsonData(response.body())))
.onErrorReturn(throwable -> FilmResult.crashedBurned(throwable.getMessage()))
.startWith(FilmResult.inflight());
final ObservableTransformer<CharacterUiEvent, CharacterResult> characterAction =
events -> events.flatMap(event -> new CheckCharacterAction(event.getData()).execute().subscribeOn(Schedulers.io()))
.map(response -> CharacterResult.landedSafely(new JsonData(response.body())))
.onErrorReturn(throwable -> CharacterResult.crashedBurned(throwable.getMessage()))
.startWith(CharacterResult.inflight());
final ObservableTransformer<UiEvent, ? extends Result> whatever = events -> events.publish(shared -> Observable.merge(
shared.ofType(SearchUiEvent.class).compose(searchAction),
shared.ofType(CharacterUiEvent.class).compose(characterAction),
shared.ofType(FilmUiEvent.class).compose(filmAction)));
/**
*
*/
final UiModel initialState = SearchUiModel.idle();
final Observable<? extends Result> results = uiEvents.compose(whatever).doOnSubscribe(COMPOSITE_DISPOSABLE::add);
final Observable<UiModel> models = results.scan(initialState, (state, result) -> {
Log.e(TAG, "scan() state = " + state + " result = " + result);
if (result.getLifecycle().equals(SearchResult.LIFECYCLE.DEPARTURE_LOUNGE) ||
result.getLifecycle().equals(CharacterResult.LIFECYCLE.DEPARTURE_LOUNGE) ||
result.getLifecycle().equals(FilmResult.LIFECYCLE.DEPARTURE_LOUNGE)) {
return SearchUiModel.idle();
}
if (result.getLifecycle().equals(SearchResult.LIFECYCLE.IN_FLIGHT) ||
result.getLifecycle().equals(CharacterResult.LIFECYCLE.IN_FLIGHT) ||
result.getLifecycle().equals(FilmResult.LIFECYCLE.IN_FLIGHT)) {
return SearchUiModel.inProgress();
}
if (result.getLifecycle().equals(SearchResult.LIFECYCLE.LANDED_SAFELY) ||
result.getLifecycle().equals(CharacterResult.LIFECYCLE.LANDED_SAFELY) ||
result.getLifecycle().equals(FilmResult.LIFECYCLE.LANDED_SAFELY)) {
return SearchUiModel.success((JsonData) result.getData());
}
if (result.getLifecycle().equals(SearchResult.LIFECYCLE.CRASHED_BURNED) ||
result.getLifecycle().equals(CharacterResult.LIFECYCLE.CRASHED_BURNED) ||
result.getLifecycle().equals(FilmResult.LIFECYCLE.CRASHED_BURNED)) {
return SearchUiModel.failure(result.getErrorMessage());
}
return null;
});
models.doOnSubscribe(COMPOSITE_DISPOSABLE::add).subscribe(model -> report(model), throwable -> error(throwable));
As soon as my activity displays I get the following logs:-
2018-10-09 14:22:33.310 D/MainActivity: report() called with: model = [UiModel{isProgress=false, message='null', isSuccess=false, data=null}]
2018-10-09 14:22:33.311 E/MainActivity: scan() state = UiModel{isProgress=false, message='null', isSuccess=false, data=null} result = SearchResult{lifecycle=IN_FLIGHT, data=null, errorMessage='null'}
2018-10-09 14:22:33.311 D/MainActivity: report() called with: model = [UiModel{isProgress=true, message='null', isSuccess=false, data=null}]
2018-10-09 14:22:33.313 E/MainActivity: scan() state = UiModel{isProgress=true, message='null', isSuccess=false, data=null} result = CharacterResult{lifecycle=IN_FLIGHT, data=null, errorMessage='null'}
2018-10-09 14:22:33.313 D/MainActivity: report() called with: model = [UiModel{isProgress=true, message='null', isSuccess=false, data=null}]
2018-10-09 14:22:33.313 E/MainActivity: scan() state = UiModel{isProgress=true, message='null', isSuccess=false, data=null} result = FilmResult{lifecycle=IN_FLIGHT, data=null, errorMessage='null'}
2018-10-09 14:22:33.313 D/MainActivity: report() called with: model = [UiModel{isProgress=true, message='null', isSuccess=false, data=null}]
Im guessing I get these IN FLIGHT results due to my .startWith() statements.
When I either click my Search button or enter any text in my EditText views I see the following logs:-
2018-10-09 14:55:19.463 E/MainActivity: scan() state = UiModel{isProgress=false, message='null', isSuccess=true, data=com.test.model.JsonData#5e0b6f1} result = FilmResult{lifecycle=LANDED_SAFELY, data=com.test.model.JsonData#8ae4d86, errorMessage='null'}
2018-10-09 14:55:19.463 D/MainActivity: report() called with: model = [UiModel{isProgress=false, message='null', isSuccess=true, data=com.test.model.JsonData#8ae4d86}]
Why do I not see "IN FLIGHT" then "LANDED SAFELY"?
I only get "LANDED SAFELY"
Is my approach to transforming between UI Event -> Action -> Result -> UI Model anywhere close to what is described by Mr J Wharton?
Where have I gone wrong?
UPDATE (II)
My mistake was to not include all my downstream Rx within the .flatmap() operation.
CLARIFICATION
Does this pattern of UI Event ---> Action ---> Result ---> UI Model still apply for cases where there is no "Backend" as such? e.g. a Home screen could present the user with a number of options (buttons) to navigate to lower level screens within the application. The UI Event would be "Button Click" the UI Model would return with the associated Activity class to employ with the startActivity() method call.
How can I amalgamate the UI input events of a login screen into a single stream of UI events where I have two EditText fields (User Name and Password) and a Login Button.
I would want the button click UI event to contain the user name and user password entered. If I was using RxBinding to process the EditTexts and the Login button click I cannot see how I can combine these three Observables into my UI event stream and have the EditTexts validated to ensure they have data entered and then pass this user entered data to my back end login API (or maybe Google Sign In for example)
(I was adding a comment but it was too long)
I cannot help with the talks and so on presented by Jake. But regarding your last question:
Does this pattern of UI Event ---> Action ---> Result ---> UI Model
still apply for cases where there is no "Backend" as such?
It does, it is just that the backend is your application state repository.
In this kind of architecture there should only be one place of truth for your application: be it a backend, a local database, a combination of both or whatever solution is appropriate for your usecase.
Having that in mind your Action streams should modify the state either by doing calls to the backend, posting changes to a database or writing elements in the sharedSetting. Similarly, changes in your state should trigger sending Results down your streams.
The specific details would depend on what you use as a source of truth for your application.
DataFlow and State
It uses mainly Paco and Jake Wharton RxState idea plus added some more stuff.
To use UiEvent → Action, Result → UiModel transformers and always act
on a single state with the help of RxJava operators (Forming a single
stream of events, then based on their types handling actions with
different transformers, then combine results again, modifying the
state and then finally render it on the UI.
or not to use transformers and make it a little bit “simpler”.
So here is the “full” view model code without using any transformers:
class SomeViewModel(private val someRepository: SomeRepository): ViewModel() {
val uiEvents: PublishSubject<UiEvent> = PublishSubject.create()
val outputState: MutableLiveData<Result<UiState>> = MutableLiveData()
init {
uiEvents.subscribe {
when (it) {
is FirstEvent -> getSomeResultsFromRepo(it.id)
is SecondEvent -> handleSecondEvent()
}
}
}
fun getSomeResultsFromRepo(id: String) {
someRepository.getResult(id)
.map { UiState(it) }
.map { Result.success(it) }
.startWith(Result.loading())
.onErrorReturn { handleError(it) }
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe({
outputState.postValue(it)
})
}
fun handleSecondEvent() {
/* do something here */
someRepository.getSomeOtherResult()
.map { UiState(it) }
.map { Result.success(it) }
.startWith(Result.loading())
.onErrorReturn { handleError(it) }
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe({
outputState.postValue(it)
})
}
private fun handleError(error: Throwable): Result<UiState> {
return if (error is RetrofitException) {
when (error.kind) {
RetrofitException.Kind.NETWORK -> Result.failure(NetworkError(error))
RetrofitException.Kind.HTTP -> Result.failure(ServerError(error))
RetrofitException.Kind.UNEXPECTED -> Result.failure(UnknownError(error))
else -> Result.failure(UnknownError(error))
}
} else {
Result.failure(UnknownError(error))
}
}
class Factory #Inject constructor(private val someRepo: SomeRepository) : ViewModelProvider.Factory {
override fun <T : ViewModel?> create(modelClass: Class<T>): T {
#Suppress("UNCHECKED_CAST")
return SomeViewModel(someRepo) as T
}
}
}
As you can see here 2 streams: a uiEvents (1st stream) which gets all the input events from the UI. As long as the UI exists it will be catching those events. Based on the event types it calls some repository functions (use cases) that are returning some response and then they are updating the model (2nd stream) with one of the possible outcomes: Success, Error or Loading.
Also transform the errors in API to so called RetrofitErrors, and based on their type it can show different error messages to the User.
There is some duplication as well that can be avoided easily, but what I wanted to show here is that it always start with a Loading result, then either a Success or an Error.
One of the most important thing is that this way "To keep state in the stream, which is a LiveData."
One benefit of this setup (just like using a BehaviourSubject) is that it will always return the last state — on orientation change it is very useful as it just loads the last available state.
Also it is highly testable as each piece can be tested in separation with providing mocked repo or view and it is also very easy to debug as we always have a current state in the stream.