How to transform a blocking code into a reactive code - spring-webflux

I looking for a good way to code this:
MyCloudDTO saveInCloud(MyCloudDTO dto) {
//sync http call :-(
return cloudService.save(dto);
}
MyData saveInDb(MyData data) {
//database call
return repository.save(data);
}
MyDTO save(MyDTO dto) {
MyCloudDTO cloudDTO = mapper.map(dto);
dto.setCloudId(saveInCloud(dto).getId());
MyData data = mapper2.map(dto);
dto.setDbId(saveInDb(data).getId());
return dto;
}
With Spring WebFlux and Monos.
The main problem here is that I want to keep the base dto during all the process because the mappers map only the properies they need and leave the the rest.
I found a way to do that but I'm not sure that's the correct/best way to do:
Mono<MyCloudDTO> saveInCloud(MyCloudDTO dto) {
return reactiveCloudService.save(dto);
}
Mono<MyData> saveInDb(MyData data) {
return reactiveRepository.save(data);
}
Mono<MyDTO> save(MyDTO dto) {
Mono<MyDTO> baseMono = Mono.just(dto);
Mono<MyCloudDTO> saveCloudMono = Mono.just(dto)
.map(mapper::map)
.flatMap(this::saveInCloud);
Mono<MyDTO> mergeAfterCloudSave = Mono.zip(
baseMono,
saveCloudMono,
(base, cloudDto) -> base.idCloud(cloudDto.getId())); //the setter return this
Mono<MyData> saveDbMono = mergeAfterCloudSave
.map(mapper2::map)
.flatMap(this::saveInCloud);
Mono<MyDTO> mergeAfterDbSave = Mono.zip(
mergeAfterCloudSave,
saveDbMono,
(base, dbData) -> base.idDb(data.getId())); //the setter return this
return mergeAfterDbSave;
}
Thank you very much!
Saveriu

Related

Exclude specific products from Product Indexer in Shopware 6

We have four specific products with a massive amount of variants. When running the Product Indexer we run out of memory because of these products.
So we want to exclude these specific products from the Product Indexer Job.
My first approach was to use the ProductIndexerEvent, but the event is dispatched at the end of the handle() method :
(vendor/shopware/core/Content/Product/DataAbstractionLayer/ProductIndexer.php:187),
which is probably too late.
What is the best approach to implement that behaviour?
I would advise against excluding products from being indexed. There's business logic relying on the data being indexed.
If you're confident in what you're doing and know about the consequences, you could decorate the ProductIndexer service.
<service id="Foo\MyPlugin\ProductIndexerDecorator" decorates="Shopware\Core\Content\Product\DataAbstractionLayer\ProductIndexer">
<argument type="service" id="Foo\MyPlugin\ProductIndexerDecorator.inner"/>
</service>
In the decorator you would have to deconstruct the original event, filter the WriteResult instances by excluded IDs and then pass the reconstructed event to the decorated service.
class ProductIndexerDecorator extends EntityIndexer
{
const FILTERED_IDS = ['9b180c61ddef4dad89e9f3b9fa13f3be'];
private EntityIndexer $decorated;
public function __construct(EntityIndexer $decorated)
{
$this->decorated = $decorated;
}
public function getDecorated(): EntityIndexer
{
return $this->decorated;
}
public function getName(): string
{
return $this->getDecorated()->getName();
}
public function iterate($offset): ?EntityIndexingMessage
{
return $this->getDecorated()->iterate($offset);
}
public function update(EntityWrittenContainerEvent $event): ?EntityIndexingMessage
{
$originalEvents = clone $event->getEvents();
if (!$originalEvents) {
return $this->getDecorated()->update($event);
}
$event->getEvents()->clear();
/** #var EntityWrittenEvent $writtenEvent */
foreach ($originalEvents as $writtenEvent) {
if ($writtenEvent->getEntityName() !== 'product') {
$event->getEvents()->add($writtenEvent);
continue;
}
$results = [];
foreach ($writtenEvent->getWriteResults() as $result) {
if (\in_array($result->getPrimaryKey(), self::FILTERED_IDS, true)) {
continue;
}
$results[] = $result;
}
$event->getEvents()->add(new EntityWrittenEvent('product', $results, $event->getContext()));
}
return $this->getDecorated()->update($event);
}
public function handle(EntityIndexingMessage $message): void
{
$data = array_diff($message->getData(), self::FILTERED_IDS);
$newMessage = new ProductIndexingMessage($data, $message->getOffset(), $message->getContext(), $message->forceQueue());
$this->getDecorated()->handle($newMessage);
}
public function getTotal(): int
{
return $this->getDecorated()->getTotal();
}
public function getOptions(): array
{
return $this->getDecorated()->getOptions();
}
}

How to return a Flux in async/reactive webclient request with subscribe method

I am using spring hexagonal architecture (port and adapter) as my application need to read the stream of data from the source topic, process/transforms the data, and send it to destination topic.
My application need to do the following actions.
Read the data (which will have the call back url)
Make an http call with the url in the incoming data (using webclient)
Get the a actual data and it needs to be transformed into another format.
Send the transformed data to the outgoing topic.
Here is my code,
public Flux<TargeData> getData(Flux<Message<EventInput>> message)
{
return message
.flatMap(it -> {
Event event = objectMapper.convertValue(it.getPayload(), Event.class);
String eventType = event.getHeader().getEventType();
String callBackURL = "";
if (DISTRIBUTOR.equals(eventType)) {
callBackURL = event.getHeader().getCallbackEnpoint();
WebClient client = WebClient.create();
Flux<NodeInput> nodeInputFlux = client.get()
.uri(callBackURL)
.headers(httpHeaders -> {
httpHeaders.setContentType(MediaType.APPLICATION_JSON);
List<MediaType> acceptTypes = new ArrayList<>();
acceptTypes.add(MediaType.APPLICATION_JSON);
httpHeaders.setAccept(acceptTypes);
})
.exchangeToFlux(response -> {
if (response.statusCode()
.equals(HttpStatus.OK)) {
System.out.println("Response is OK");
return response.bodyToFlux(NodeInput.class);
}
return Flux.empty();
});
nodeInputFlux.subscribe( nodeInput -> {
SourceData source = objectMapper.convertValue(nodeInput, SourceData.class);
// return Flux.fromIterable(this.TransformImpl.transform(source));
});
}
return Flux.empty();
});
}
The commented line in the above code is giving the compilation as subscribe method does not allow return types.
I need a solution "without using block" here.
Please help me here, Thanks in advance.
I think i understood the logic. What do you may want is this:
public Flux<TargeData> getData(Flux<Message<EventInput>> message) {
return message
.flatMap(it -> {
// 1. marshall and unmarshall operations are CPU expensive and could harm event loop
return Mono.fromCallable(() -> objectMapper.convertValue(it.getPayload(), Event.class))
.subscribeOn(Schedulers.parallel());
})
.filter(event -> {
// 2. Moving the if-statement yours to a filter - same behavior
String eventType = event.getHeader().getEventType();
return DISTRIBUTOR.equals(eventType);
})
// Here is the trick 1 - your request below return Flux of SourceData the we will flatten
// into a single Flux<SourceData> instead of Flux<List<SourceData>> with flatMapMany
.flatMap(event -> {
// This WebClient should not be created here. Should be a singleton injected on your class
WebClient client = WebClient.create();
return client.get()
.uri(event.getHeader().getCallbackEnpoint())
.accept(MediaType.APPLICATION_JSON)
.exchangeToFlux(response -> {
if (response.statusCode().equals(HttpStatus.OK)) {
System.out.println("Response is OK");
return response.bodyToFlux(SourceData.class);
}
return Flux.empty();
});
})
// Here is the trick 2 - supposing that transform return a Iterable of TargetData, then you should do this and will have Flux<TargetData>
// and flatten instead of Flux<List<TargetData>>
.flatMapIterable(source -> this.TransformImpl.transform(source));
}

What is the best possible way to send custom error responses in .net core web api

I'm making a .net Core WebApi using .Net Core 2.2. The API is ready but the failure message and response is where I'm stuck at.
Right now, I'm getting respose like below
json
{
"empId":1999,
"empName":"Conroy, Deborah",
"enrollmentStatus":true,
"primaryFingerprintScore":65,
"secondaryFingerprintScore":60,
"primaryFingerprint":null,
"secondaryFingerprint":null,
"primaryFingerprintType":null,
"secondaryFingerprintType":null}
}
I created a json formatter class and wrote the below code
public class SuperJsonOutputFormatter : JsonOutputFormatter
{
public SuperJsonOutputFormatter(
JsonSerializerSettings serializerSettings,
ArrayPool<char> charPool) : base(serializerSettings, charPool)
{
}
public override async Task WriteResponseBodyAsync(
OutputFormatterWriteContext context,
Encoding selectedEncoding)
{
if (context == null)
throw new ArgumentNullException(nameof(context));
if (selectedEncoding == null)
throw new ArgumentNullException(nameof(selectedEncoding));
using (TextWriter writer =
context.WriterFactory(
context.HttpContext.Response.Body,
selectedEncoding))
{
var rewrittenValue = new
{
resultCode = context.HttpContext.Response.StatusCode,
resultMessage =
((HttpStatusCode)context.HttpContext.Response.StatusCode)
.ToString(),
result = context.Object
};
this.WriteObject(writer, rewrittenValue);
await writer.FlushAsync();
}
}
I expect all the error codes to be sent as generic error messages like the JSON below.
FOR STATUS OKAY:
{
"status" : True,
"error" : null,
"data" : {
{
"empId":1999,
"empName":"Conroy, Deborah",
"enrollmentStatus":true,
"primaryFingerprintScore":65,
"secondaryFingerprintScore":60,
"primaryFingerprint":null,
"secondaryFingerprint":null,
"primaryFingerprintType":null,
"secondaryFingerprintType":null}
}
}
}
FOR OTHER STATUS LIKE 404, 500, 400, 204
{
"status" : False,
"error" : {
"error code" : 404,
"error description" : Not Found
},
"data" : null
}
I expect all the error codes to be sent as generic error messages like the JSON below
You're almost there. What you need to do is enabling your SuperJsonOutputFormatter.
A Little Change to Your Formatter
Firstly, your formatter didn't return a json with the same schema as you want. So I create a dummy class to hold the information for error code and error description:
public class ErrorDescription{
public ErrorDescription(HttpStatusCode statusCode)
{
this.Code = (int)statusCode;
this.Description = statusCode.ToString();
}
[JsonProperty("error code")]
public int Code {get;set;}
[JsonProperty("error description")]
public string Description {get;set;}
}
And change your WriteResponseBodyAsync() method as below:
...
using (TextWriter writer = context.WriterFactory(context.HttpContext.Response.Body, selectedEncoding)) {
var statusCode = context.HttpContext.Response.StatusCode;
var rewrittenValue = new {
status = IsSucceeded(statusCode),
error = IsSucceeded(statusCode) ? null : new ErrorDescription((HttpStatusCode)statusCode),
data = context.Object,
};
this.WriteObject(writer, rewrittenValue);
await writer.FlushAsync();
}
Here the IsSucceeded(statusCode) is a simple helper method that you can custom as you need:
private bool IsSucceeded(int statusCode){
// I don't think 204 indicates that's an error.
// However, you could comment out it if you like
if(statusCode >= 400 /* || statusCode==204 */ ) { return false; }
return true;
}
Enable your Formatter
Secondly, to enable your custom Formatter, you have two approaches: One way is to register it as an global Formatter, the other way is to enable it for particular Controller or Action. Personally, I believe the 2nd way is better. So I create a Action Filter to enable your formatter.
Here's an implementation of the Filter that enables your custom formatter dynamically:
public class SuperJsonOutputFormatterFilter : IAsyncActionFilter{
private readonly SuperJsonOutputFormatter _formatter;
// inject your SuperJsonOutputFormatter service
public SuperJsonOutputFormatterFilter(SuperJsonOutputFormatter formatter){
this._formatter = formatter;
}
// a helper method that provides an ObjectResult wrapper over the raw object
private ObjectResult WrapObjectResult(ActionExecutedContext context, object obj){
var wrapper = new ObjectResult(obj);
wrapper.Formatters.Add(this._formatter);
context.Result= wrapper;
return wrapper;
}
public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
{
ActionExecutedContext resultContext = await next();
// in case we get a 500
if(resultContext.Exception != null && ! resultContext.ExceptionHandled){
var ewrapper = this.WrapObjectResult(resultContext, new {});
ewrapper.StatusCode = (int) HttpStatusCode.InternalServerError;
resultContext.ExceptionHandled = true;
return;
}
else {
switch(resultContext.Result){
case BadRequestObjectResult b : // 400 with an object
var bwrapper=this.WrapObjectResult(resultContext,b.Value);
bwrapper.StatusCode = b.StatusCode;
break;
case NotFoundObjectResult n : // 404 with an object
var nwrapper=this.WrapObjectResult(resultContext,n.Value);
nwrapper.StatusCode = n.StatusCode;
break;
case ObjectResult o : // plain object
this.WrapObjectResult(resultContext,o.Value);
break;
case JsonResult j : // plain json
this.WrapObjectResult(resultContext,j.Value);
break;
case StatusCodeResult s: // other statusCodeResult(including NotFound,NoContent,...), you might want to custom this case
var swrapper = this.WrapObjectResult(resultContext, new {});
swrapper.StatusCode = s.StatusCode;
break;
}
}
}
}
And don't forget to register your formatter as a service :
services.AddScoped<SuperJsonOutputFormatter>();
Finally, when you want to enable your formatter, just add a [TypeFilter(typeof(SuperJsonOutputFormatterFilter))] annotation for the controller or action.
Demo
Let's create an action method for Test:
[TypeFilter(typeof(SuperJsonOutputFormatterFilter))]
public IActionResult Test(int status)
{
// test json result(200)
if(status == 200){ return Json(new { Id = 1, }); }
// test 400 object result
else if(status == 400){ return BadRequest( new {}); }
// test 404 object result
else if(status == 404){ return NotFound(new { Id = 1, }); }
// test exception
else if(status == 500){ throw new Exception("unexpected exception"); }
// test status code result
else if(status == 204){ return new StatusCodeResult(204); }
// test normal object result(200)
var raw = new ObjectResult(new XModel{
empId=1999,
empName = "Conroy, Deborah",
enrollmentStatus=true,
primaryFingerprintScore=65,
secondaryFingerprintScore=60,
primaryFingerprint = null,
secondaryFingerprint= null,
primaryFingerprintType=null,
secondaryFingerprintType=null
});
return raw;
}
Screenshot:

NHinernate - Serializing Criteria to json and back. for a web interface usage

I have a web interface with a lot of data grids that allow the user passing a search criteria to the server.
I don't want to actually build an explicit method that will handle each grid individually, so I thought to allow passing JSON criteria from the client to the server.
This code
string res = JsonConvert.SerializeObject(Restrictions.Eq("id", "1"));
will return will return {"PropertyName":"id","Value":"1"} which is exactly what I wanted to pass from the client - perfect.
but this code with or statement:
string res = JsonConvert.SerializeObject(Restrictions.Or(Restrictions.Eq("id", "1"),Restrictions.Eq("id", "2")))
will return {}
What is the way to convert JSON into a Criteria and back in nHibernate.
To be more accurate, I have something like this in the client, and I want my server to support it. I can serialize the client ui to json.
Thanks
The empty json serialization happens because newtonsoft can only serialize public fields.
The code below will serialize all fields of a class regardless of its visibility.
public class MyContractResolver : DefaultContractResolver
{
protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
{
var props = type.GetProperties(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)
.Select(p => base.CreateProperty(p, memberSerialization))
.Union(type.GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)
.Select(f => base.CreateProperty(f, memberSerialization)))
.ToList();
props.ForEach(p => { p.Writable = true; p.Readable = true; });
return props;
}
}
...
var myOrs = Restrictions.Or(Restrictions.Eq("id", "1"), Restrictions.Eq("id", "2"));
var settings = new JsonSerializerSettings()
{
ContractResolver = new MyContractResolver()
};
string json = JsonConvert.SerializeObject(myOrs, settings);
Now to deserialize this json we have a problem, the NHibernate classes are either abstract or don't have a public empty constructor.
You will need to create a custom class to deserialize.
public class MyConverter : JsonConverter
{
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException("Not implemented yet");
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
JObject obj = JObject.Load(reader);
if (obj.Value<string>("Op") == "or")
{
var leftJObject = obj["LeftHandSide"];
var rightJObject = obj["RightHandSide"];
var left = new SimpleExpression(leftJObject.Value<string>("PropertyName"), GetJTokenValue(leftJObject["Value"]), leftJObject.Value<string>("Op"));
var right = new SimpleExpression(rightJObject.Value<string>("PropertyName"), GetJTokenValue(rightJObject["Value"]), rightJObject.Value<string>("Op"));
return Restrictions.Or(left, right);
}
//TODO: The rest of the restrictions
return null;
}
public override bool CanWrite
{
get { return false; }
}
public override bool CanConvert(Type objectType)
{
return true;
}
private object GetJTokenValue(JToken token)
{
if (token.Type == JTokenType.String)
{
return token.Value<string>();
}
else if (token.Type == JTokenType.Integer)
{
return token.Value<Int32>();
}
//TODO: The rest of the types
return null;
}
}
...
var result = JsonConvert.DeserializeObject<AbstractCriterion>(json, new MyConverter());

Exposing BLOC streams via fields, methods, or getter

I am using the BLOC pattern for my latest Flutter app and I started out using something like this for my output streams:
class MyBloc {
// Outputs
final Stream<List<Todo>> todos;
factory MyBloc(TodosInteractor interactor) {
final todosController = BehaviorSubject<List<Todo>>()
..addStream(interactor.todos);
return MyBloc._(todosController);
}
MyBloc._(this.todos);
}
but slowly I found myself doing something more like this, using a method (or getter) after awhile:
class MyBloc {
final TodosInteractor _interactor;
// Outputs
Stream<List<Todo>> todos(){
return _interactor.todos;
}
MyBloc(this._interactor) { }
}
For people who want to see... getter for todos in TodosInteractor:
Stream<List<Todo>> get todos {
return repository
.todos()
.map((entities) => entities.map(Todo.fromEntity).toList());
}
When I look at the differing code, I see that the first example uses a field versus a method to expose the stream but I couldn't figure out why I would choose one over the other. It seems to me that creating another controller just to push through the stream is a little much... Is there a benefit to this other than being immutable in my todos stream definition? Or am I just splitting hairs?
Well maybe this will not be a best answer but it is a good practice expose your output stream using get methods. Below a example of a bloc class that i have written to a project using RxDart.
class CityListWidgetBloc {
final _cityInput = PublishSubject<List<Cidade>>();
final _searchInput = new PublishSubject<String>();
final _selectedItemsInput = new PublishSubject<List<Cidade>>();
// exposing stream using get methods
Observable<List<Cidade>> get allCities => _cityInput.stream;
Observable<List<Cidade>> get selectedItems => _selectedItemsInput.stream;
List<Cidade> _searchList = new List();
List<Cidade> _selectedItems = new List();
List<Cidade> _mainDataList;
CityListWidgetBloc() {
//init search stream
_searchInput.stream.listen((searchPattern) {
if (searchPattern.isEmpty) {
_onData(_mainDataList); // resend local data list
} else {
_searchList.clear();
_mainDataList.forEach((city) {
if (city.nome.toLowerCase().contains(searchPattern.toLowerCase())) {
_searchList.add(city);
}
});
_cityInput.sink.add(_searchList);
}
});
}
//getting data from firebase
getCity( {#required String key}) {
FirebaseStateCityHelper.getCitiesFrom(key, _onData);
//_lastKey = key;
}
searchFor(String pattern) {
_searchInput.sink.add(pattern);
}
void _onData(List<Cidade> list) {
_mainDataList = list;
list.sort((a, b) => (a.nome.compareTo(b.nome)));
_cityInput.sink.add(list);
}
bool isSelected(Cidade item) {
return _selectedItems.contains(item);
}
void selectItem(Cidade item) {
_selectedItems.add(item);
_selectedItemsInput.sink.add(_selectedItems);
}
void selectItems(List<Cidade> items){
_selectedItems.addAll( items);
_selectedItemsInput.sink.add( _selectedItems );
}
void removeItem(Cidade item) {
_selectedItems.remove(item);
_selectedItemsInput.sink.add(_selectedItems);
}
dispose() {
_cityInput.close();
_searchInput.close();
_selectedItemsInput.close();
}
}