Concurrency with Kotlin Flow
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In this short demo, you’ll see how to handle errors in flows.
@OptIn(ExperimentalCoroutinesApi::class)
private fun moviesForCategory(categoryId: String): Flow<List<MovieViewState>> =
movieRepository.categories()
.filter { it.id == categoryId }
.flatMapLatest { movieCategory -> movieRepository.fetchMoviesForCategory(movieCategory.name) }
.map { movies ->
movies.map { movie ->
val imageRes = movieRepository.fetchMovieImage(movieId = movie.id)
MovieViewState(movie.id, movie.title, "", imageRes)
}
}
.catch { throwable -> // HERE
Log.e("CategoryViewModel", "Error happened", throwable)
emit(emptyList())
}
fun fetchMoviesForCategory(categoryName: String): Flow<List<Movie>> = flow {
if (categoryName == "Action") { // HERE
throw RuntimeException("Error fetching Action movies")
}
val movies = movieService.fetchMoviesForCategory(categoryName)
emit(movies)
}