Код ниже реализует простой экран, который показывает список пользователей, использующих шаблон MVI с сопрограммами kotlin. Код работает, но не дает никаких результатов. После многих отладок я обнаружил, что функция getUsers в UserListVM ничего не излучает. Был бы признателен за помощь здесь. Большое спасибо.
class UserListVM : ViewModel() {
val resultFlows: Channel<Flow<*>> = Channel(Channel.UNLIMITED)
val liveState = MutableLiveData<PModel<*, UserListIntents>>()
val intents: Channel<UserListIntents> = Channel()
lateinit var job: Job
lateinit var currentState: UserListState
fun offer(event: UserListIntents) = intents.offer(event)
suspend fun store(initialState: UserListState): LiveData<PModel<*, UserListIntents>> {
job = viewModelScope.launch {
currentState = initialState
intents.consumeEach { intent ->
resultFlows.send(reduceIntentsToResults(intent, currentState)
.flowOn(Executors.newFixedThreadPool(4).asCoroutineDispatcher())
.map { SuccessResult(it, intent) }
.catch { ErrorEffectResult(it, intent) }
.onStart { emit(LoadingEffectResult(intent)) }
.distinctUntilChanged()
)
}
resultFlows.consumeEach { results ->
results.flatMapMerge {
val states = stateStream(this as Flow<Result<UserListResult, UserListIntents>>, currentState)
val effects = effectStream(this as Flow<Result<UserListEffect, UserListIntents>>)
flowOf(states, effects)
}
.flattenMerge()
.collect { pModel -> liveState.value = pModel }
}
}
job.start()
return liveState
}
private suspend fun reduceIntentsToResults(intent: UserListIntents, currentState: Any): Flow<*> {
Log.d("UserListVM", "currentStateBundle: $currentState")
return when (intent) {
is GetPaginatedUsersIntent -> when (currentState) {
is EmptyState, is GetState -> getUsers()
else -> throwIllegalStateException(intent)
}
is UserClickedIntent -> when (currentState) {
is GetState -> flowOf((SuccessEffectResult(NavigateTo(intent.user), intent)))
else -> throwIllegalStateException(intent)
}
}
}
private suspend fun getUsers(): Flow<UsersResult> {
return flow {
emit(UsersResult(listOf(User("user1", 1), User("user2", 2), User("user3", 3))))
}.flowOn(Dispatchers.IO)
}
override fun onCleared() {
super.onCleared()
job.cancel()
}
}
class UserListActivity : AppCompatActivity() {
var intentStream: Flow<UserListIntents> = flowOf()
lateinit var viewModel: UserListVM
lateinit var viewState: UserListState
private lateinit var usersAdapter: GenericRecyclerViewAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
initialize()
setupUI(savedInstanceState == null)
viewModel.store(viewState).observe(this, Observer {
it?.apply {
when (this) {
is ErrorEffect -> bindError(errorMessage, error, intent)
is SuccessEffect -> bindEffect(bundle as UserListEffect)
is SuccessState -> {
(bundle as UserListState).also { state ->
viewState = state
bindState(state)
}
}
}
toggleLoadingViews(intent)
}
})
}
fun initialize() {
viewModel = getViewModel()
viewState = EmptyState()
}
fun setupUI(isNew: Boolean) {
setContentView(R.layout.activity_user_list)
setSupportActionBar(toolbar)
toolbar.title = title
setupRecyclerView()
}
override fun onResume() {
super.onResume()
if (viewState is EmptyState) {
GlobalScope.launch {
viewModel.offer(GetPaginatedUsersIntent(0))
}
}
}
private fun bindState(successState: UserListState) {
usersAdapter.setDataList(successState.list, successState.callback)
}
private fun bindEffect(effectBundle: UserListEffect) {
when (effectBundle) {
is NavigateTo -> {
// ..
}
}
}
fun bindError(errorMessage: String, cause: Throwable, intent: UserListIntents) {
//..
}
private fun setupRecyclerView() {
usersAdapter = object : GenericRecyclerViewAdapter() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): GenericViewHolder<*> {
return when (viewType) {
R.layout.empty_view -> EmptyViewHolder(layoutInflater
.inflate(R.layout.empty_view, parent, false))
R.layout.user_item_layout -> UserViewHolder(layoutInflater
.inflate(R.layout.user_item_layout, parent, false))
else -> throw IllegalArgumentException("Could not find view of type $viewType")
}
}
}
usersAdapter.setAreItemsClickable(true)
user_list.layoutManager = androidx.recyclerview.widget.LinearLayoutManager(this)
user_list.adapter = usersAdapter
usersAdapter.setAllowSelection(true)
intentStream = flowOf(intentStream, user_list.scrollEvents()
.map { recyclerViewScrollEvent ->
GetPaginatedUsersIntent(
if (ScrollEventCalculator.isAtScrollEnd(recyclerViewScrollEvent))
viewState.lastId
else -1)
}
.filter { it.lastId != -1L }
.conflate()
.onEach { Log.d("NextPageIntent", "fired!") })
.flattenMerge()
}
fun toggleLoadingViews(isLoading: Boolean, intent: UserListIntents?) {
linear_layout_loader.bringToFront()
linear_layout_loader.visibility = if (isLoading) View.VISIBLE else View.GONE
}
}