RxJava为项列表创建可观察链

Question

How do I return an observable which will emit multiple items after performing a webservice call for all items in a List?

So I have a webservice which saves for example a single "car". I retrieve a list of "cars" from the UI and I want to save all these individually but I only want to subscribe to 1 Observable. So I basically want to create some sort of chain of multiple Observables depending on the amount of "cars" received from the UI and I want every result of the webservie emitted by the single Observable. Once all the "cars" are saved int he webservice the single Observable may onComplete.

Answer 1

I am using Retrofit for calling web service with RxJava like this :

Request :

Observable<ResponsePOJO> getCars(Param param);

Call getCars and handle response :

client.getCars(param)
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(Response -> {
                   // Success
                }, e -> {
                    // Error
                });

Answer 2

I might be misunderstanding, but isn't this just a case where you could flatmap from the list to the individual items?

public Observable<Car> getCars() {
   return api.getCars()
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .flatMap(new Func1<List<Car>, Observable<Car>>() {
                @Override public Observable<Car> call(List<Car> carlist) {
                    return Observable.from(carlist);
                }
            });
}

With this, the onNext(Car car) will be called multiple times and whenever the entire list is handled, onCompleted() is called. In this example I used the network as a source for my list, but I imagine this can as well be the UI.

I Hope this is what you are looking for, otherwise, please elaborate and I'll think along with you ;)

Answer 3

I think you just need to use Observable.from and if you need to create an Observable per car just use flatMap operator. Once you finish you just need to subscribe.

@Test
public void flatMapCars() {
    Observable.from(getCars())
            .flatMap(this::saveCar)
            .subscribe();
}

private List<String> getCars() {
    return Arrays.asList("Aston martin", "Renault", "Seat");
}

private Observable<String> saveCar(String car) {
    return Observable.just(car);//You should save the car
}