How to use Zip operator of kotlin flow in Android

Question

In my application I want combine two deferent API with ZIP operator of Kotlin flow.!
Api 1 is Movies list and Api 2 is genres list!
I want loaded each 2 Apis in one time, for this I used zip operator!
My work is true? Can I combine 2 deferent Apis with them?

ApiServices :

interface ApiServices {
    @GET("movies")
    suspend fun moviesList(): Response<MoviesList>

    @GET("genres")
    suspend fun genresList(): Response<GenresList>
}

Repository class:

class Repository @Inject constructor(private val api: ApiServices) {

    suspend fun moviesList(): Flow<Response<MovieList>> {
        return flow {
            emit(api.moviesList(1))
        }
    }

    suspend fun genresList(): Flow<Response<GenresList>> {
        return flow {
            emit(api.genresList())
        }
    }
}

I know show error for add deferent model class in moviesList !

But I want know how can I use Zip operator for combine 2 deferent Apis?

Answer 1

You could use combine(flow1,flow2) method to combine the flow and zipping your api response using zip , for example :

class ViewModel @Inject constructor(private val repository: Repository) : ViewModel() {

    val moviesFlow = repository.moviesList()
    val genresFlow = repository.genresList()

    fun loadMoviesAndGenres() : Flow<List<Pair<Type1,Type2>>> = combine(moviesFlow, genresFlow) { movieList: Response<MovieList>, genreList:Response<GenresList> ->
       val movies = movies.body()?.data
       val genres = genres.body()
       return@combine movies?.zip(genres)
    }
}

How to use zip :

val listMovieTittle = listOf("avanger", "conjuring", "other")
val listGenre = listOf("action", "horror", "fantasy", "thriller")

val result1 : List<Pair<String,String>> = listMovieTittle .zip(listGenre)
println(result1 ) // [(avanger, action), (bconjuring, horror), (other, fantasy)]

val result2  : List<String> = listMovieTittle .zip(listGenre) { a, b -> "$a + $b" }
println(result2) // [avanger + action, conjuring + horror, other + fantasy]