Hi all, I am confused how to use Single with Completable properly. I have a get method that returns ...

# rx

[Jason]

Hi all, I am confused how to use Single with Completable properly.
I have a get method that returns Single<Data> and a other method just do saving data and return nothing ( Completable )

Code looks like below :

fun getUserInfo() : Single<UserInfo>

fun save(token: Token) : Completable

fun initialize() {
    getUserInfo()
        .flatMap { 
            // Get token from UserInfo : val token = userInfor.getToken()
            // Call save(token: Token) method to save data
        }
        .subscribeOn(<http://Schedulers.io|Schedulers.io>())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribeBy(
            onSuccess = {
                // HERE:  Using UserInfo to do somtehing
            },
            onError = {
                Log.d(it)
            }
        )
}

How to write code inside flatMap block ? ( Or is there other operator suitable with this use case?)

[Daniel Rodak]

You can use `andThen`:

.flatMap { 
            // Get token from UserInfo : val token = userInfor.getToken()
            // Call save(token: Token) method to save data: save(token).andThen(Single.just(userInfo))
        }

[uli]

I guess the problem is, you should not use flat map for side effects.

[uli]

How about doOnNext?

[Jason]

.flatMap { userInfo ->
                save(userInfor.token())                    .onErrorComplete()
.toSingleDefault(userInfo)
            }

I wrote like above.

[Jason]

doOnNext can not be applied because this is Single<T> . It’s emit all in one time

[Jason]

@uli I do not use flatmap for side effects

[uli]

@Jason isn't save(token) a side effect? The name suggests, that it modifies global state