Incorrect message body size to deserialize to a Long rabbit MQ java Micronaut

Question

I am getting a serialization exception as Incorrect message body size to deserialize to a Long as I understand that it is not able to serialize the LONG

Micronaut RabbitMQ producer

@RabbitProperty(name = "replyTo", value = "amq.rabbitmq.reply-to")
    @Binding(ConstantValues.COUNT_CATEGORY)
    Maybe<Long> Count(String id);

Micornaut RabbitMQ Listener

@Queue(ConstantValues.COUNT_CATEGORY)
    public Maybe<Long> Count(String id) {
        LOG.info(String.format("Listener --> Count category for specified id = %s", id));
        CategorySearchCriteria criteria = new CategorySearchCriteria();
        criteria.setId(id);
        Bson query = QueryBuilder.QueryBuilder(criteria, Bson.class).get(0);
        var item = Single.fromPublisher(
                this.repository.getCollection(ConstantValues.PRODUCT_CATEGORY_COLLECTION_NAME, Category.class)
                        .countDocuments(query)).blockingGet();
        return Maybe.just(item);
    }

Error

io.micronaut.core.serialize.exceptions.SerializationException: Incorrect message body size to deserialize to a Long
    at io.micronaut.rabbitmq.serdes.JavaLangRabbitMessageSerDes$LongSerDes.deserialize(JavaLangRabbitMessageSerDes.java:314)
    at io.micronaut.rabbitmq.serdes.JavaLangRabbitMessageSerDes$LongSerDes.deserialize(JavaLangRabbitMessageSerDes.java:306)
    at io.micronaut.rabbitmq.serdes.JavaLangRabbitMessageSerDes.deserialize(JavaLangRabbitMessageSerDes.java:81)
    at io.micronaut.rabbitmq.intercept.RabbitMQIntroductionAdvice.deserialize(RabbitMQIntroductionAdvice.java:323)
    at io.micronaut.rabbitmq.intercept.RabbitMQIntroductionAdvice.lambda$intercept$22(RabbitMQIntroductionAdvice.java:268)
    at io.reactivex.internal.operators.flowable.FlowableFlatMap$MergeSubscriber.onNext(FlowableFlatMap.java:132)
    at io.micronaut.reactive.rxjava2.RxInstrumentedSubscriber.onNext(RxInstrumentedSubscriber.java:59)
    at io.reactivex.internal.operators.flowable.FlowableTimeoutTimed$TimeoutSubscriber.onNext(FlowableTimeoutTimed.java:101)
    at io.micronaut.reactive.rxjava2.RxInstrumentedSubscriber.onNext(RxInstrumentedSubscriber.java:59)
    at io.reactivex.internal.subscriptions.DeferredScalarSubscription.complete(DeferredScalarSubscription.java:132)
    at io.reactivex.internal.operators.single.SingleToFlowable$SingleToFlowableObserver.onSuccess(SingleToFlowable.java:62)
    at io.micronaut.reactive.rxjava2.RxInstrumentedSingleObserver.onSuccess(RxInstrumentedSingleObserver.java:65)
    at io.reactivex.internal.operators.single.SingleFlatMap$SingleFlatMapCallback$FlatMapSingleObserver.onSuccess(SingleFlatMap.java:111)
    at io.micronaut.reactive.rxjava2.RxInstrumentedSingleObserver.onSuccess(RxInstrumentedSingleObserver.java:65)
    at io.reactivex.internal.operators.single.SingleDoFinally$DoFinallyObserver.onSuccess(SingleDoFinally.java:73)
    at io.micronaut.reactive.rxjava2.RxInstrumentedSingleObserver.onSuccess(RxInstrumentedSingleObserver.java:65)
    at io.reactivex.internal.operators.single.SingleCreate$Emitter.onSuccess(SingleCreate.java:67)
    at io.micronaut.rabbitmq.reactive.RxJavaReactivePublisher$3.handleDelivery(RxJavaReactivePublisher.java:324)
    at com.rabbitmq.client.impl.ConsumerDispatcher$5.run(ConsumerDispatcher.java:149)
    at com.rabbitmq.client.impl.ConsumerWorkService$WorkPoolRunnable.run(ConsumerWorkService.java:104)

I know this is a serialization issue, but quite not sure how to fixed it.

Answer 1

I was missing the point from Micronaut documentation

RPC consumer methods must never return a reactive type. Because the resulting publish needs to occur on the same thread and only a single item can be emitted, there is no value in doing so.

change the listener method

  @Queue(ConstantValues.COUNT_CATEGORY)
    public Long Count(String id) {
        LOG.info(String.format("Listener --> Count category for specified id = %s", id));
        CategorySearchCriteria criteria = new CategorySearchCriteria();
        criteria.setId(id);
        Bson query = QueryBuilder.QueryBuilder(criteria, Bson.class).get(0);
        return Single.fromPublisher(
                this.repository.getCollection(ConstantValues.PRODUCT_CATEGORY_COLLECTION_NAME, Category.class)
                        .countDocuments(query)).blockingGet();
    }