CODEWITHSUNDEEP
androidkotlinrx-javaandroid-architecture-componentsandroid-livedata
Jono
Jono

Reputation: 18118

Rxjava return LiveData list

Hi i am trying to use rxjava along with a LiveData that gets transformed using Map before i return it. However it saying i need to return something from inside the map.

I tried doing return Single.just(pianoStorage.getAllFavItems()) and it complains that you are not allowed to return something?

override fun getFavouriteItems() : Single<LiveData<MutableList<Items>>>{
        //check if db has offers
        if (storage.getAllFavItems().value!!.isEmpty()){
             getAllFavItems().map {
                 {offers : ItemsResponse ->
                     storage.saveAllItemsLists(offers)
                     Single.just(storage.getAllFavItems())
                 }
             }.subscribe(
                     {offers ->
                         return@subscribe
                     }
             )
        }else{
            return Single.just(storage.getAllFavItems())
        }
    }

The code below basically checks my persistent database if i have some items there and if not, fetch it from the network using retrofit(the getAllFavItems())

This network call gets all the list of items and then what i need to do is first save it to the storage and then get only the favourite items from it afterwords using the below:

@Query("SELECT * FROM items WHERE state = 'Fav'")
    fun getAllFavItems(): LiveData<MutableList<Item>>

Upvotes: 1

Views: 814

Answers (2)

LordRaydenMK
LordRaydenMK

Reputation: 13321

If you change your DAO definition to:

@Query("SELECT * FROM items WHERE state = 'Fav'")
fun getAllFavItems(): Flowable<MutableList<Item>>

You can do something like this:

getAllFavItems()
    .flatMap({
        if(it.isEmpty()) {
            getAllFavItems().toFlowable(BackpressureStrategy.XXX)
                .doOnNext({storage.saveAllItemsLists(it)})
                .map {/*TODO: convert from ItemsResponse to List<Item>*/}
        } else {
            Flowable.just(it)
        }
    })

The code emits changes to the favorite items. If there are 0 favorite items it will call the getAllFavItems() function and insert the results into db (inserting the results will cause getAllFavitems() to emit again).

Upvotes: 1

Kevin Robatel
Kevin Robatel

Reputation: 8386

Change to:

getAllFavItems().map { offers : ItemsResponse ->
    storage.saveAllItemsLists(offers)
    Single.just(storage.getAllFavItems())
}

You have twice { and } inside map.

Upvotes: 0

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