I have the following method:
internal typealias MaybeError<T> = Either<GenericError, T>
override fun createCompany(companyDomain: CompanyDomain): MaybeError<CompanyDomain> =
checkCompany(companyDomain).map { it.toEntity() }.fold({ Either.left(it) }) { company ->
with (companyRepository) {
isCompanyExists(company).fold({ Either.left(it) }) { isExists ->
if (isExists) return#with Either.left(CompanyNameExists(companyDomain))
createCompany(company).fold({ Either.right(companyDomain) }) { Either.left(it) }
}
}
}
Is there a better/more idiomatic way to write this using Arrow?
It is hard to refactor because I can only assume what used methods should return. But I guess the methods returns MaybeError. In this case we can omit fold({ Either.left(it) }) and we can use map or flatMap.
internal typealias MaybeError<T> = Either<GenericError, T>
override fun createCompany(companyDomain: CompanyDomain): MaybeError<CompanyDomain> =
checkCompany(companyDomain)
.map { it.toEntity() }
.flatMap { company ->
companyRepository.isCompanyExists(company)
.flatMap { isExists ->
if (isExists) {
MaybeError.left(CompanyNameExists(companyDomain))
} else {
companyRepository.createCompany(company)
}
}
}
Related
I have this:
val navigateToMainFragmentEvent: StateFlow<State<Event<Boolean>>>
if (navigateToMainFragmentEvent.collectAsState().value is State.TriggerState) {
(viewModel.navigateToMainFragmentEvent.collectAsState().value
as State.TriggerState).data.getContentIfNotHandled()
?.let {
if (it) {
Timber.tag("Nurs").d("collect as state ")
navController.popBackStack()
navController.navigate(MAIN_SCRENN)
}
}
}
is it possible to shorten with generics the if statement?
val state = navigateToMainFragmentEvent.value
if (state is State.TriggerState) {
state.data.getContentIfNotHandled()?.let {
// do sth
}
}
As an advice: You can define ifNotHandled method with a lambda argument in your Event class to more shortening:
fun ifNotHandled(callback: () -> T) {
if (!hasBeenHandled) {
hasBeenHandled = true
callback.invoke(content)
}
}
val state = navigateToMainFragmentEvent.value
if (state is State.TriggerState) {
state.data.ifNotHandled {
// do sth
}
}
var responseMap = mutableMapOf<VendorType, ChargeResponse>()
requests.forEach {
val response = when (it.vendorType) {
VendorType.Type1 -> service.chargeForType1()
VendorType.Type2 -> service.chargeForType2()
else -> {
throw NotImplementedError("${it.vendorType} does not support yet")
}
}
responseMap[it.vendorType] = response
}
responseMap
So I want all the service.charge function run in separate thread. Return the map when all is done
Hope to solve your problem:
Assume your service and request like this:
interface Service {
suspend fun chargeForType1(): ChargeResponse
suspend fun chargeForType2(): ChargeResponse
}
data class Request(val vendorType: VendorType)
suspend fun requestAll(requests: List<Request>): Map<VendorType, ChargeResponse> {
return coroutineScope {
requests
.map { request ->
async {
request.vendorType to when (request.vendorType) {
VendorType.Type1 -> service.chargeForType1()
VendorType.Type2 -> service.chargeForType2()
else -> throw NotImplementedError("${request.vendorType} does not support yet")
}
}
}
.awaitAll()
.toMap()
}
}
Please have a look at the piece of code below. Now suppose i'll have hundreds of entity like "person". How would you code such a thing to get it clean, concise, efficient, well structured ? Tx
class HttpEntryPoint : CoroutineVerticle() {
private suspend fun person(r: RoutingContext) {
val res = vertx.eventBus().requestAwait<String>("/person/:id", "1").body()
r.response().end(res)
}
override suspend fun start() {
val router = Router.router(vertx)
router.get("/person/:id").coroutineHandler { ctx -> person(ctx) }
vertx.createHttpServer()
.requestHandler(router)
.listenAwait(config.getInteger("http.port", 8080))
}
fun Route.coroutineHandler(fn: suspend (RoutingContext) -> Unit) {
handler { ctx ->
launch(ctx.vertx().dispatcher()) {
try {
fn(ctx)
} catch (e: Exception) {
e.printStackTrace()
ctx.fail(e)
}
}
}
}
}
You're looking for subrouter.
https://vertx.io/docs/vertx-web/java/#_sub_routers
From the top of my head:
override suspend fun start() {
router.mountSubrouter("/person", personRouter(vertx))
// x100 if you'd like
}
Then in your PersonRouter.kt:
fun personRouter(vertx: Vertx): Router {
val router = Router.router(vertx)
router.get("/:id").coroutineHandler { ctx -> person(ctx) }
// More endpoints
return router
}
Try in rxJava2 Kotlin combine Single with Flowable but nothing not happening:
Does not undrstand what wrong
Flowable.create<Int>({ emmit ->
loadNewListener = object :Listener {
override fun onEmit(id: Int) {
emmit.onNext(id)
}
}
}, BackpressureStrategy.LATEST)
.debounce(500, TimeUnit.MILLISECONDS)
.flatMapSingle {
loadNew(id = it.id)
}
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe({ (data:Data) ->
}, {
Timber.e("Failed load data ${it.message}")
})
my method is returning Single:
private fun loadNew(id: Int): Single<Data> {
return when (pdfType) {
CASE_0 -> {
Single.create<Data> { emmit ->
service.get("data")
.enqueue(
object : Callback<Void> {
override fun onFailure(call: Call<Void>?, t: Throwable?) {
// failure
}
override fun onResponse(call: Call<Void>?, response: Response<Void>?) {
emmit.onSuccess(it.data)
}
}
}//single
}//case_0
CASE_1 -> 1Repository.loadsome1Rx(id = id).map { it.getData() }
CASE_2 -> 2Repository.loadsom2LocalRx(id = id).map { it.getData() }
else -> {
throw java.lang.RuntimeException("$this is not available type!")
}
}
What is wrong im my code?
Need Maby call Single in Flowable subscribe() seppurate
like this?
Flowable.create<Int>({ emmit ->
loadNewListener = object :Listener {
override fun onEmit(id: Int) {
emmit.onNext(id)
}
}
}, BackpressureStrategy.LATEST)
.debounce(500, TimeUnit.MILLISECONDS)
.subscribe({
loadNew(id = it.id)
}, {
Timber.e("")
})
This code is workin but looks not simple as via combine try.
This simple example based on your code is working
var i = 0
fun foo() {
Flowable.create<Int>({ emmit ->
emmit.onNext(i)
i++
}, BackpressureStrategy.LATEST)
.debounce(500, TimeUnit.MILLISECONDS)
.flatMapSingle {
Single.create<String> { emmit ->
emmit.onSuccess("onSuccess: $it")
}
}
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe({
Log.i("RX", "Subscribe: $it")
}, {
it.printStackTrace()
})
}
Check SingleEmitter.onSuccess() and SingleEmitter.onError() is called in all cases in when (pdfType)...
As #Stas Bondar said in answer below This simple example based on your code is working!!
Problem was in loadNewListener .
It does not init in time and has null value when need. Call create Flowable on init ViewModel but loadNewListener did not have time to create when i call him from fragment.
loadNewListener = object :Listener{...}
Becuse need some time mutch for init rxJava expression!
And combine flowable with single via flatMapSingle spent more time than just call single on flowable dubscrinbe!
So use temp field:
private var temp: Temp? = null
fun load(id: Int) {
loadNewListener.apply {
when {
this != null -> load(id = id)
else -> userEmitPdfTemp = Temp(id = id)
}
}
}
Flowable.create<Data>({ emmit ->
userEmitPdfTemp?.let {id->
emmit.onNext(Data(id))
userEmitPdfTemp =null
}
loadNewListener = object :Listener {
override fun load(id: Int) {
emmit.onNext(Data(id))
}
}
}
I have the following code
class CurrencyRepository #Inject constructor(val apiInterface: ApiInterface,
val ratesDao: RatesDao) {
fun getRates(): Observable<List<Rates>> {
val observableFromApi = getCurrencyFromApi()
val observableFromDb = getRatesFromDb()
return Observable.concatArrayEager(observableFromApi , observableFromDb)
}
private fun getCurrencyFromApi(): Observable<Currency> {
return apiInterface.getRates()
.doOnNext {
Timber.i(it.toString())
val map = it.rates
val keys = map.keys
for (key in keys) {
ratesDao.insertRate(Rates(key , map.get(key)))
}
}
}
private fun getRatesFromDb(): Observable<List<Rates>> {
return ratesDao.getAllRates()
.toObservable()
.doOnNext {
for (rate in it) {
Timber.i("Repository DB ${it.size}")
}
}
}
}
In getCurrencyFromApi(), getRates() returns me an Observable<Currency>. I would like this particular function to return Observable<List<Rates>> so that I can use it in Observable.concatArrayEager inside getRates() of CurrencyRepository
Currency contains a Map object which can be transformed into a List object. I am not clear on how to do that inside getCurrencyFromApi()
One of possible solutions is
fun getRatesFromApi(): Observable<List<Rates>> {
return apiInterface.getRates()
.flatMapIterable { it.rates.entries }
.map { Rates(it.key ,it.value) }
.doOnNext { ratesDao.insertRate(it) }
.toList()
.toObservable()
}
I advise you insert items in database in one batch, because it will be more efficient.