Reactive Data

rx-transformers-reactive-data.java

public class ReactiveData<T> {

  @Getter
  private final T value;

  @Getter
  private final Throwable error;

  public ReactiveData(T value) {
    this.value = value;
    this.error = null;
  }

  public ReactiveData(Throwable error) {
    this.value = null;
    this.error = error;
  }

  public ReactiveData(T value, Throwable error) {
    this.value = value;
    this.error = error;
  }

  public boolean hasError() {
    return error != null;
  }

  public boolean noError() {
    return error == null;
  }
}




public static <T, R> Observable.Transformer<T, ReactiveData<R>> switchMapReactiveData(Func1<T, Observable<R>> onwardCall) {
    return new Observable.Transformer<T, ReactiveData<R>>() {

      private R previousValue = null;

      @Override
      public Observable<ReactiveData<R>> call(Observable<T> observable) {
        return observable.switchMap(
            a -> onwardCall.call(a)
                .doOnNext(value -> previousValue = value)
                .map(ReactiveData::new)
                .onErrorReturn(e -> new ReactiveData<>(previousValue, e))
        );
      }
    };
  }