Observable fromIterable do not insert item to Room

Question

I faced very strange issue and have no idea why it is happening. When I have stream with fromIterable to insert to Room items one by one, it does not insert. No exceptions, nothing. I even put breakpoint to generated Room DAO implementation class, it call method but does not go inside Completable block, just ignoring it.

repository.insert(mapper.transform(item))
                    .flatMap { id ->
                        Observable.fromIterable(item.tags)
                                .map { tag ->
                                    anotherRepository.insert(
                                            JoinEntity(id, tag.id)
                                    )
                                }
                                .toList()
                                .flatMap { Single.just(id) }
                    }

But if I will remove fromIterable, and replace with direct insert call, it does work and it inserts normally. Without any other changes.

repository.insert(mapper.transform(item))
                    .flatMap { id ->
                        anotherRepository.insert(JoinEntity(1, 1))
                                .andThen(Single.just(id))

                    }

I tried so many things already and still have no ideas. Tried flattenAsFlowable, also does not work.

Will appreciate any help. Thanks!

Answer 1

Okey, found out the issue, maybe will help somebody.

repository.insert(mapper.transform(item))
                    .flatMap { id ->
                        Observable.fromIterable(item.tags)
                                .filter { tag -> tag.id != null }
                                .flatMapSingle { tag -> anotherRepository.insert(JoinEntity(id, tag.id)) }
                                .toList()
                                .flatMap { Single.just(id) }
                    }

I've changed map/flatMap to flatMapSingle, so its actually being emitted.