Combine RxTextView text change events with Retrofit call

Question

I'm new with RxJava and just trying to implement a few examples to better understand whats going on so I what I have thought is an EditText which is an Observable and emits textChangeEvents using RxBinding library :

        RxTextView.textChangeEvents(searchbar.getEditText())
            .debounce(400, TimeUnit.MILLISECONDS)
            .filter(new Func1<TextViewTextChangeEvent, Boolean>() {
                @Override
                public Boolean call(TextViewTextChangeEvent text) {
                    return (text.text().length() > 2);
                }
            })
            .subscribeOn(AndroidSchedulers.mainThread())
            .observeOn(Schedulers.io());

and a Retrofit api call where the text for the call is from the Observable above.

So I have declared a function :

@Override
public Observable<SearchResponse> executeSearch(Observable<RxTextView> queryText) {
    return searchService.getSearch(queryText)
            .subscribeOn(Schedulers.newThread())
            .observeOn(AndroidSchedulers.mainThread());
}

And now I have to combine those two so when text changes there's a new Retrofit call but I don't know how I can "pass" the queryText to the service.

I also tried :

Observable<TextViewTextChangeEvent>  
    searchBarText = RxTextView.textChangeEvents(searchbar.getEditText())
            .debounce(400, TimeUnit.MILLISECONDS)
            .filter(new Func1<TextViewTextChangeEvent, Boolean>() {
                @Override
                public Boolean call(TextViewTextChangeEvent text) {
                    Timber.i("Executes!!! text : %s", text.text().toString());
                    return (text.text().length() > 2);
                }
            })
            .subscribeOn(AndroidSchedulers.mainThread())
            .observeOn(Schedulers.io());

    Observable.combineLatest(executeSearchTypeOne(searchBarText), executeSearchTypeTwo(searchBarText),
                    new Func2<TypeOne, TypeTwo, Object>() {
                        @Override
                        public Object call(TypeOne one, TypeTwo two) {

                            return null;
                        }
                    })
            .subscribe(new Action1<Object>() {
                @Override
                public void call(Object o) {
                    Timber.i("WORKS!!!");
                }
            });

where I want to run two Retrofit calls concurrently based on EditText changes but they don't run at all

Answer 1

I assume searchService.getSearch queryText parameter's type is String, and return an Observable of Data.

I would write it that way:

RxTextView.textChangeEvents(searchbar.getEditText())
        .debounce(400, TimeUnit.MILLISECONDS)
        .map(new Func1<TextViewTextChangeEvent, String>() {
            @Override
            public String call(TextViewTextChangeEvent text) {
                return text.text().toString();
            }
        })
        .filter(new Func1<String, Boolean>() {
            @Override
            public Boolean call(String text) {
                return (text.length() > 2);
            }
        })
        .flatMap(new Func1<String, rx.Observable<Data>>() {
            @Override
            public rx.Observable<Data> call(String text) {
                return getSearch(text);
            }
        })
        .subscribeOn(Schedulers.io()) // Or Schedulers.newThread()
        .observeOn(AndroidSchedulers.mainThread());

This is an Observable of Data, from an Observable of TextViewTextChangeEvent mapped to String to chain with getSearch, an Observable Data.

For Kotlin (initial proposal by Killer):

RxTextView.textChangeEvents(searchbar.getEditText())
                .debounce(400, TimeUnit.MILLISECONDS) // Better store the value in a constant like Constant.DEBOUNCE_SEARCH_REQUEST_TIMEOUT
                .map { it.text().toString() }
                .filter { it.length > 2 }
                .flatMap { getSearch(it) } // Or .flatMap(this::getSearch)
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe { ... }

Note: RxTextView.textChanges will not emit text changes once onError() method is run. Reference: https://github.com/JakeWharton/RxBinding/issues/272