CODEWITHSUNDEEP
androidretrofitrx-android
guillaume-tgl
guillaume-tgl

Reputation: 2856

Improve request cancelling in RxJava

I'm starting using RxAndroid in my existing application. I've started with a quite simple activity where I have a search field and I contact an API using Retrofit when the text changes. I also want to cancel the current unfinished request if there's one before starting a new one. Here is what I have so far:

private Subscription currentRequestSubscription = null;

// Create stream of filtered queries
Observable<String> queryObservable = RxTextView.textChanges(searchView)
            .startWith("")
            .debounce(DELAY_BEFORE_REQUEST, TimeUnit.MILLISECONDS)
            .map(new Func1<CharSequence, String>() {
                @Override
                public String call(CharSequence charSequence) {
                    return charSequence.toString();
                }
            })



// Make search request and update UI
queryObservable.observeOn(Schedulers.io())
        .subscribe(new Action1<String>() {
            @Override
            public void call(String query) {
                if (currentRequestSubscription != null) {
                    currentRequestSubscription.unsubscribe();
                }

                currentRequestSubscription = createAPIRequestObservable(query)
                        .observeOn(AndroidSchedulers.mainThread())
                        .subscribe(... update UI with results ...);
            }
        });

I feel like storing the subscription is not really reactive programming compliant. How could I do this in a more standard way?

Upvotes: 1

Views: 1116

Answers (1)

AndroidEx
AndroidEx

Reputation: 15824

No need to create a new subscription each time in this case, switchMap can take care of unsubscribing from the old observable when a new comes in. Something like this:

currentRequestSubscription = RxTextView.textChanges(searchView)
        .observeOn(Schedulers.io())
        .startWith("")
        .debounce(DELAY_BEFORE_REQUEST, TimeUnit.MILLISECONDS)
        .map(CharSequence::toString)
        .switchMap(text -> createAPIRequestObservable(text).subscribeOn(Schedulers.io()))
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(/*... update UI with results ...*/);

Also good example.

Upvotes: 5

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