Tukukkk

I have a database table with friend connections:

The next example is just a Imagined example, so please not suggest me to implement this in another way.

FriendConnection:

• id


• humanId

I have a list with these id's.

val friendConnections = arrayListOf(

    FriendConnection(id=10, humanId=141),

    FriendConnection(id=13, humanId=142)

)

I want to make this result list with RxJava.

val friendList = arrayListOf(

    Friend(friendConnectionId = 10, humanId = 141, humanInstance = (...)),

    Friend(friendConnectionId = 13, humanId = 142, humanInstance = (...))

)

How I can get a human?

fun getHumanById(id: Long) : Single<Human>

So I need to iterate the friendConnections and make a Single call for every Human. Than I need to map the FriendConnection with the new Human instance to Friend instance.

I tried it but it's not work:

Observable.fromIterable(arrayListOf(

                FriendConnection(id=10, humanId=141),

                FriendConnection(id=13, humanId=142)

        ))

                .flatMapSingle { friendConnection ->

                    repository.getHumanById(friendConnection.humanId)

                            ?.map {human ->

                                Friend(friendConnection.id,friendConnection.humanId,human)

                            }

                }

                .toList()

                .subscribeOn(Schedulers.io())

                .observeOn(AndroidSchedulers.mainThread())

                .subscribe({ it ->

                    Timber.i("friendList is here: $it")

                }, {

                    throw it 

                })

Someone have idea what's wrong? (I want to implement it with Rx, not with Room)

Is this solution suitable for you?

Observable.fromIterable(

        listOf(

            FriendConnection(1, 101),

            FriendConnection(2, 102)

        )

    )

        .flatMapSingle { connection ->

            getHumanById(connection.humanId)

                .map { human -> Friend(connection.id, connection.humanId, human) }

        }

        .toList()

        .subscribe { list -> println(list) } //method reference generates error due to methods ambiguity

Mock function for getting a human by id:

private fun getHumanById(id: Long): Single<Human> = Single.just(Human(id, id.toString()))

You could do something like this,

Observable.fromIterable(friendConnections)

        .flatMap { Observable.just(Friend(it.id, it.humanId, repository.getHumanById(it.humanId).blockingGet())) }

        .toList()

        .subscribe {it --> /*Your Operation*/