I'm new into rxJava and it's making my head spin. Basically I'm pulling data from youtube api with retrofit which gives back Observable and with youtubeDataMapper I'm mappng it into Youtube Pojo object which contains String videoID. So my question is, how to make this method return that string instead of Completable?
This is my method:
@Override
public Completable downloadVideoUrl(String query) {
addSubscription(youtubeApi.getYoutubeId(query, Constants.youtubeApi)
.map(youtubeDataMapper::map)
.subscribeOn(subscribeScheduler)
.observeOn(observeScheduler)
.subscribe());
return Completable.complete();
}
You have two choices:
Make your downloadVideoUrl
return Observable
instead of Completable
:
Preferred way:
@Override
public Completable downloadVideoUrl(String query) {
return youtubeApi.getYoutubeId(query, Constants.youtubeApi)
.map(youtubeDataMapper::map)
.subscribeOn(subscribeScheduler)
.observeOn(observeScheduler);
}
Notice lack of subscribe
operator here.
Then wherever you want to get videoId:
downloadVideoUrl(query)
.subscribe(new Subscriber<String>() {
@Override
public void onCompleted() {
}
@Override
public void onError(Throwable e) {
}
@Override
public void onNext(String videoId) {
// do whatever you want with videoId
}
});
Use toBlocking().first()
This is not preffered as you block current Thread
until Observable
finishes
@Override
public String downloadVideoUrl(String query) {
return youtubeApi.getYoutubeId(query, Constants.youtubeApi)
.map(youtubeDataMapper::map)
.subscribeOn(subscribeScheduler)
.observeOn(observeScheduler)
.toBlocking().first();
}
First of all, it is better to make Retrofit return Single instead of Observable because you are expecting a single server response (and not a sequence of responses).
Secondly, Completable.complete() is a factory method for a Completable that does nothing at all. So you don’t need it here.
Regarding String videoID, it depends on what you are planning to do with it. Also, I have no idea what your .addSubscription() is doing.
I would suggest doing something like the following:
class YourClass {
private final CompositeSubscription compositeSubscription = new CompositeSubscription();
// you must call compositeSubscription.clear() either in class .finalize() or on some UI lifecycle event
void yourMethod() {
final Single videoID = youtubeApi.getYoutubeId(query, Constants.youtubeApi)
.map(youtubeDataMapper::map)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread());
final Subscription subscription = videoID.subscribe(new SingleSubscriber() {
@Override
public void onSuccess(String value) {
// TODO: do whatever with the value
}
@Override
public void onError(Throwable error) {
// TODO: log and/or display error
}
});
compositeSubscription.add(subscription);
}
}
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