Issue
I'm using Single.fromCallable() to make a network call and I want to use the data from the response to make a second call.
How can I chain these two calls instead of nesting them?
private void queryForUser() {
Single.fromCallable(() -> remoteRepository.queryForUser()))
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(response-> {
String username = response.getUsername();
//Perform second call
performSecondQuery(username);
}, err -> {
Log.e(TAG, "Failed to get user", err);
});
}
private void performSecondQuery(String username){
Single.fromCallable(() -> remoteRepository.performSecondQuery(username)))
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(secondQueryResult -> {
Log.d(TAG, "performSecondQuery: " + secondQueryResult);
}, err -> {
Log.e(TAG, "Failed to perform second query", err);
});
}
Solution
My Java lambda syntax is rusty, but using flatMap() should give you something like this:
private Single<Whatever> performSecondQuery(String username){
return Single.fromCallable(() -> remoteRepository.performSecondQuery(username)))
}
private void queryForUser() {
Single.fromCallable(() -> remoteRepository.queryForUser()))
.flatMap { response -> performSecondQuery(response.getUsername()) }
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(
// TODO something with the result
}, err -> {
Log.e(TAG, "Failed to get user", err);
});
}
(note: I don't know what the second query is doing, so I don't know what Whatever is — it would be the return type of remoteRepository.performSecondQuery())
Answered By - CommonsWare
Answer Checked By - Clifford M. (JavaFixing Volunteer)
