RxJava-组合两个观察值

Question

我需要将另一个改装请求中的图像合并到其特定系列中。听起来很简单的任务把我带进了反应式的地狱，没有一丝希望。

具体来说，我还通过可观察创建服务，因为我需要获取身份验证令牌来创建服务。

我的尝试基于以下答案：https://stackoverflow.com/a/28418503/2192545.

public void loadSeries(String searchFor) {

    mainView.showLoadingIndicator();
    if (subscription != null) subscription.unsubscribe();


    TVApplication application = TVApplication .get(mainView.getContext());

    application.getTVService()
            .flatMap(service -> service.searchSeries(searchFor)
                    .flatMap(series -> Arrays.asList(series).stream()
                            .<List<Series>>flatMap(aSeries -> {
                                Observable<Series> obsSeries = Observable.just(aSeries);
                                Observable<ImageListWrapper> obsImages = service.queryImages(aSeries.getId(), "poster");
                                return Observable.zip(obsSeries, obsImages, (Series s, ImageListWrapper i) -> combineSeriesData(s, i));
                            })));
}

private Series combineSeriesData(Series s, ImageListWrapper i) {
    s.setPosters(i.getImages());
    return s;
}

我有点不知所措。我只是在Observable的Func2部分得到了“无法推断函数接口类型”。在IDE中，构建日志显示：

Error:(63, 58) error: incompatible types: bad return type in lambda 

expression
no instance(s) of type variable(s) T1,T2,R exist so that Observable<R> conforms to Stream<? extends List<Series>>
where T1,T2,R are type-variables:
T1 extends Object declared in method <T1,T2,R>zip(Observable<? extends T1>,Observable<? extends T2>,Func2<? super T1,? super T2,? extends R>)
T2 extends Object declared in method <T1,T2,R>zip(Observable<? extends T1>,Observable<? extends T2>,Func2<? super T1,? super T2,? extends R>)
R extends Object declared in method <T1,T2,R>zip(Observable<? extends T1>,Observable<? extends T2>,Func2<? super T1,? super T2,? extends R>)

Answer 1

好吧，首先要做的事；不要将服务创建为可观察的，这会使您的代码更加困难。这是有办法的。

其次，您不需要使用zip：

application
  .getTVService()
  .flatMap(service ->
     service
     .searchSeries(searchFor)
     .flatMapIterable(series -> series)
     .flatMap(aSeries -> 
        service
        .queryImages(aSeries.getId(), "poster")
        .map(i ->  combineSeriesData(aSeries, i))
     )
  );