The guts of it is here: ```interface DataService {...

# micronaut

[Mark Fisher]

The guts of it is here:

interface DataService {
    fun createMaybeObjects(count: Int): Maybe<List<Data>>
    fun createListObjects(count: Int): List<Data>
}

@Singleton
class DefaultDataService(private val repo: DataRepository) : DataService {

    override fun createMaybeObjects(count: Int): Maybe<List<Data>> {
        return Maybe.fromCallable { repo.createList(count) }
    }

    override fun createListObjects(count: Int): List<Data> {
        return Maybe.fromCallable { repo.createList(count) }.blockingGet()
    }
}

@Singleton
class DataRepository {
    private val mapper = jacksonObjectMapper().configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)

    fun createList(num: Int): List<Data> {
        val data = mapper.readValue<Data>("bad data")
        return MutableList(num) { data }
    }
}

data class Data(
        val name: String,
        val size: Int
)

the line val data = mapper.readValue<Data>("bad data") causes an exception, which is sometimes picked up by an ExceptionHandler, sometimes not.
The code for the handler is:

@Produces
@Singleton
@Requires(classes = [Exception::class, ExceptionHandler::class])
class GlobalExceptionHandler : ExceptionHandler<Exception, HttpResponse<Any>> {

    override fun handle(request: HttpRequest<Any>, exception: Exception): HttpResponse<Any> {
        println("handle called")
        exception.printStackTrace()
        return HttpResponse.serverError(0)
    }
}

It's all in the repo linked with notes and a simple build.