Asynchronous code is basically smarter use of semantics-to-compiled code as I see it. Without the need for spawning new threads, we basically achieve the same thing when coming to I/O. (but without the weight of threads)

Is there a difference between

webClient.get()...awaitExchange().awaitBody()

and

webClient.get()...retrieve().awaitBody()

?

Only if you want to do something with the mono from the exchange

ie. retryBackoff, to leverage that on the exchange level

ok, so If i’m only concerned about the body of the response, I can simply

retrieve().awaitBody()

You are probably looking to use awaitExchange if you want to use coroutines

retreive will be threaded, because it uses mono/flux

ok

final question about testing a

weblient().get()...awaitExchange().awaitBody()

call. I have setup a MockWebServer from OkHttp and for a first try, I just want to see if I can get the String of the body, so I did something like

@Test
fun myTest() = runBlockingTest {
  val mockResponse = MockResponse().apply { setBody("foo") }
  mockServer.enqueue(mockResponse)
  val string = webclient.get().uri(mockServer.url("/").toString).awaitExchange().awaitBody()
  assertThat(string).isEqualTo("foo")
}

But the test is crashing with

IllegaleStateException : This job has not completed yet

from

runBlockingTest

, if I switch to

runBlocking

the issue is gone and the test passes, but I would like to understand a bit why it’s not working with

runBlockingTest

Not used runBlockingTest so cant help you unfortunately. What lib is that?

it’s from kotlinx-coroutines-test

We just run junit 5 and runblocking so cant help you there

Maybe somebody here can me point into the direction with a problem I ran into testing the graphql-kotlin library. It's using the Java Publisher interface in the library to support subscriptions via a websocket. However once about 120 subscriptions have been started and stopped that websocket becomes unresponsive. The subscriptions are stopped by calling

.cancel()

but they are only really stopped once the connection with the client is broken. https://github.com/ExpediaGroup/graphql-kotlin/pull/510

Hey Guys, I try to add CORS to a spring app but I can't figure out why I can't get it to work. Requests via Postman are succeeding, requests from my frontend not. Does one of you might have an idea? Thanks in advance!

fun main(args: Array<String>) {
    runApplication<SomeApplicationName>(*args)
}


//<https://docs.spring.io/spring/docs/4.2.x/spring-framework-reference/html/cors.html>
@Configuration
@EnableWebMvc
class CorsConfig: WebMvcConfigurer {
    override fun addCorsMappings(registry: CorsRegistry) {
        registry.addMapping("/**")
    }
}

Two other attempts which didn't work out:

@Configuration
class CorsConfig : WebMvcConfigurer {
    override fun addCorsMappings(registry: CorsRegistry) {
        registry.addMapping("/**")
                .allowedOrigins("*")
                .allowedMethods("GET", "POST", "PUT", "DELETE", "HEAD")
                .allowCredentials(true)
    }
}

@Bean
fun cors(): FilterRegistrationBean<CorsFilter> {
    val source = UrlBasedCorsConfigurationSource()
    val config = CorsConfiguration()
    config.setAllowCredentials(true)
    config.setAllowedOrigins(Collections.singletonList("*"))
    config.setAllowedMethods(Collections.singletonList("*"))
    config.setAllowedHeaders(Collections.singletonList("*"))
    source.registerCorsConfiguration("/**", config)
    val bean = FilterRegistrationBean(CorsFilter(source))
    bean.setOrder(0)
    return bean
}

This should just work for your WebMVC controllers

You can use debug mode, and set breakpoint to make sure the code is executed

On the frontend, you can also clear cache, or use incognito mode

Yeah, the configuration file is executed. One thought that came to my mind was that it might be a problem that I don't have a controller yet (since HATEOAS already offers the needed GET/POST/PUT. I'll look into it when I'm in the office.

I'm attempting to use Kotlin delegates in my JPA Entities … without success. The fields that I "mix in" don't appear to get included in the final entity.

I've read these articles but the solution in the forums uses a Java class to define the final Entity and I'd rather use 100% Kotlin. • https://dzone.com/articles/mixins-with-kotlin • https://discuss.kotlinlang.org/t/delegated-classes-and-jpa-hibernate/14978/4

Is

CrudRepository.findByIdOrNull

not documented?

There's a tutorial blog post, a GitHub PR, and that's about it.

What are the different solutions for a Spring(Boot)+JavaFX application?

Hey guys, I want to play a little bit around with the kotlinx html library, but it seems that I can't make any progress in the most fundamental detail: Returning the html. Since it's a side project, I wanted to try kofu. Here's some code: routes:2

fun routes(indexController: IndexController) = router {
    GET("/index", indexController::getIndex)
    GET("/uptime", indexController::getUptime)
}

controller:

@Suppress("UNUSED_PARAMETER")
class IndexController(private val indexTemplate: IndexTemplate) {
    fun getIndex(req: ServerRequest) = ok().render("index", indexTemplate.index)

and the HTML:

import kotlinx.html.div
import kotlinx.html.dom.create
import kotlinx.html.p
import org.w3c.dom.Document

class IndexTemplate(document: Document) {
    val index = document.create.div {
        p { +"Hello" }
        p { +"you" }
    }
}

However, I can't find the way to respond with html. Unfortunately, sources about the usage of kotlinxhtml and spring are really rare (understandable ofc)

How do you do memoization with spring-cache when using

suspend fun

?

I wonder if launching

applicationEventPublished.publish(event)

in a kotlin coroutine is a good alternative to Spring’s

@Async

method for asynchronous processing of events. This is a Spring Boot application (No Webflux), so the Controller would have to implement

CoroutineScope

to avoid using GlobalScope.

Is there a Slack for Spring in general?