Callback method called multiply times

[lectricas]

public void loadTeasers(int skip, boolean refresh, Category category) {
        getViewState().showProgress();

        Subscription s2 = ActiveAndroidHelper.getSources()
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(teasers -> {
                    getViewState().onTeasersLoaded(teasers);
                    getViewState().hideProgress();
                }, this::onError);
        unsubscribeOnDestroy(s2);
    }

Suppose we have simple method which loads some data from network. I want to refresh my network data every onResume method.
And, in this case, on each call of loadTeasers(true, new Category()), the callback method onTeasersLoaded(teasers) is called N times, where N is the number of onResume methods (and loadTeasers) executed.
I think I need to unsubscribe and null the previous subsribition, but which method to use here?
Thanks

[senneco]

Well you can use this method to do it =) Just like this:

Subscription loadTeasersSubscription;

public void loadTeasers(int skip, boolean refresh, Category category) {
        if (loadTeasersSubscription != null && !loadTeasersSubscription.isUnsubscribed()) {
                loadTeasersSubscription.unsubscribe();
        }

        getViewState().showProgress();

        loadTeasersSubscription = ActiveAndroidHelper.getSources()
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(teasers -> {
                    getViewState().onTeasersLoaded(teasers);
                    getViewState().hideProgress();
                }, this::onError);

        unsubscribeOnDestroy(loadTeasersSubscription);
    }

[lectricas]

@senneco Nope, this does not work. That was only a guess about necessity to unsubsribe.
loadTeasersSubscription is not null, but unsubsribed.
I think the problem is somewhere else.
Haven't you encountered this issue already??

[senneco]

It seems that I didn't understand what is your problem. Problem is that this method call each time after onResume, or problem that it's not? Or something else?

[A-Zaiats]

What strategy do you use for onTeaserLoaded(teasers) method? Was your view stopped before resume? Are you sure that onTeaserLoaded(teasers) method is called N times from subsrciber#onNext callback?

Looks like you use default strategy. So it can be following behavior:

• the View was stopped
• the View was detached from presenter
• the View was attached to the Presenter
• the ViewState restored state (called all onTeaserLoaded(teasers) that was called before)
• one more onTeaserLoaded(teasers) was called by loadTeasers callback

@senneco can you correct me if I am wrong with Moxy lifecycle?

[lectricas]

I just call loadTeasers() each time my fragment executes OnResume method.
And I get onTeaserLoaded(teasers) executed N times (over and over, after only single OnResume call).
And this N grows every time Fragment executed OnResume method.
Suppose you have two fragments and you just moving to and fro between them. The first fragment has a presenter, where loadTeasers() method is.
So the strategy is the default one, just copied the code from the sample.

[senneco]

@lectricas it seems like bug is in your ActiveAndroidHelper.getSources(), or onTeasersLoaded(teasers) has default or AddToEndStrategy. Try to annotate your onTeasersLoaded(teasers) method with annotation @StateStrategy(AddToEndSingleStrategy.class).

[lectricas]

@senneco
LogCat.

D/MyInteger: startLoadingInFragment 
D/MyInteger: subscribeInPresenter 
D/MyInteger: CallBackInFragment:1
D/MyInteger: startLoadingInFragment
D/MyInteger: CallBackInFragment:1
D/MyInteger: subscribeInPresenter
 D/MyInteger: CallBackInFragment:1
D/MyInteger: startLoadingInFragment
 D/MyInteger: CallBackInFragment:1
D/MyInteger: CallBackInFragment:1
 D/MyInteger: subscribeInPresenter
 D/MyInteger: CallBackInFragment:1
D/MyInteger: startLoadingInFragment
D/MyInteger: CallBackInFragment:1
 D/MyInteger: CallBackInFragment:1
 D/MyInteger: CallBackInFragment:1
 D/MyInteger: subscribeInPresenter
D/MyInteger: CallBackInFragment:1

public void testInteger() {
        getViewState().showProgress();
        s3 = Observable.just(1)
        .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(integer -> {
                    Log.d("MyInteger", "subscribeInPresenter");
                    getViewState().integerTest(integer);
                    getViewState().hideProgress();
                }, this::onError);
        unsubscribeOnDestroy(s3);
    }

Seems like callback method is called by its own. Presenter calls callback method correctly - single time on each subscribe.

[senneco]

@lectricas could you provide me your MvpView interface?

[lectricas]

@senneco

public interface BaseNewsViewState extends BaseViewState {
    void onTeasersLoaded(List<Teaser> teasers);
    void onTeasersQueried(List<Teaser> teasers);
    void onCurrencyLoaded(CurrencyRequestAnswer currencyAnswer);
    void integerTest(Integer integer);
}

public interface BaseViewState extends MvpView {
    void hideProgress();
    void showProgress();
    void onError(Throwable throwable);
}

[senneco]

@lectricas try to apply AddToEndStrategy, like this:

@StateStrategy(AddToEndSingleStrategy.class)
public interface BaseNewsViewState extends BaseViewState {
    void onTeasersLoaded(List<Teaser> teasers);
    void onTeasersQueried(List<Teaser> teasers);
    void onCurrencyLoaded(CurrencyRequestAnswer currencyAnswer);
    void integerTest(Integer integer);
}

[lectricas]

@senneco

D/MyInteger: startLoadingInFragment
D/MyInteger: CallBackInFragment:1
D/MyInteger: subscribeInPresenter
D/MyInteger: CallBackInFragment:1
D/MyInteger: startLoadingInFragment
D/MyInteger: CallBackInFragment:1
D/MyInteger: subscribeInPresenter
D/MyInteger: CallBackInFragment:1
D/MyInteger: startLoadingInFragment
D/MyInteger: CallBackInFragment:1
D/MyInteger: subscribeInPresenter
D/MyInteger: CallBackInFragment:1

Better now, but first callback is kinda redundant.

[A-Zaiats]

I think SkipStrategy.class will be better.
If View is valid, callback will be called. If no, presenter reload data on resume.

[lectricas]

@A-Zaiats
woohoo
works as desired. Thanks.