kotlinlang #spring

You’re probably not leveraging the functional nature of Kotlin, which is, in my opinion, the greatest advantage. Kotlin is more expressive, more concise, safer, and truly multi-paradigm. Honestly I’ve yet to hear a good reason why sticking with java is rational. It’s usually just people that want to stick with what they already know.

xenoterracide

10/11/2019, 10:43 PM

on SAM, for example if something defines java.util.function.Function as a parameter, you then have to write

myMethod Function { foo -> bar }

in kotlin to pass the function, in java that would just be

myMethod( foo -> bar )

rrader

10/13/2019, 10:07 AM

How do you handle this situation https://github.com/spring-projects/spring-framework/issues/23789 ?

Gabriel Machado

10/14/2019, 3:50 PM

Is there a version of

spring-boot-starter-webflux

with the new coroutines support? Or I need to manually include dependencies such as

'spring-webflux', version: '5.2.0.M2'

Marko Mitic

10/15/2019, 11:41 AM

Does anyone know when SpringOne Platform 2019 recordings are going to be available? https://kotlinlang.slack.com/archives/C0922A726/p1571137314272600

👍 1

jmfayard

10/16/2019, 8:59 AM

This is really nice https://speakerdeck.com/elizarov/spring-flavored-kotlin-coroutines

❤️ 5

😒uspend: 3

Bernhard

10/17/2019, 2:45 PM

upgraded to spring boot 2.2 today and it supports @ConfigurationProperties for data classes, but how do I get rid of intellij warning me about the configuration processor not being on classpath?

bjonnh

10/18/2019, 6:08 PM

Do we have any stats on the pick up of Kotlin in the Spring world?

Peter

10/22/2019, 6:01 PM

Hello everyone, A bit about me then the question: I use Kotlin almost 5 months now. I have been programming for about 2 years total(1.5 year trying to learn Java - spring, 5 months professionally). Currently I am using Kotlin with Spring Batch & Boot. All this time I have been skipping Concurrency "for later" and I think the time has come now. I am thinking If you guys as most experienced individuals, would suggest I skip Java concurrency and dive directly to Kotlin concurrency/coroutines? Will I miss "important background" if I do that, or is it completely normal to start my journey with kotlin? Thanks. p.s. Sorry If this should go to #getting-started. I ll post there as well.

bjonnh

10/22/2019, 7:34 PM

I have an architecture question. Is there a spring-friendly approach for triggering long-running tasks? (through http for example). I would like to be able to query if that task is still running, failed, etc

mister11

10/23/2019, 8:02 AM

How much issues can blocking API calls cause in a WebFlux app if they are scheduled using

Schedulers.boundedElastic()

scheduler? At the moment, I have only some DB calls using JOOQ, but I might use some other blocking library. I've added

BlockHound

to the project and once I moved DB calls to a separate scheduler it stoped reporting blocking calls, but I'm aware that number of available threads is much smaller in Netty than in Tomcat which might cause scalability issues down the road.

Marcel Overdijk

10/31/2019, 10:34 PM

class MdcTaskDecorator implements TaskDecorator {

  @Override
  public Runnable decorate(Runnable runnable) {
    // Right now: Web thread context !
    // (Grab the current thread MDC data)
    Map<String, String> contextMap = MDC.getCopyOfContextMap();
    return () -> {
      try {
        // Right now: @Async thread context !
        // (Restore the Web thread context's MDC data)
        MDC.setContextMap(contextMap);
        runnable.run();
      } finally {
        MDC.clear();
      }
    };
  }
}

Marcel Overdijk

10/31/2019, 10:36 PM

@Configuration
@EnableAsync
class AsynchConfig : AsyncConfigurerSupport() {

    override fun getAsyncExecutor(): Executor {
        val executor = ThreadPoolTaskExecutor()
        executor.setTaskDecorator(MDCTaskDecorator())
        executor.initialize()
        return executor
    }
}

Or Cohen

11/03/2019, 12:50 PM

Hey guys. I’m Working on a Kotlin + Spring Boot 2.2 app (non reactive). I recently converted my routing definition to Kotlin DSL with

WebMvc.fn

instead of using

@RequestMapping

annotations. Since I’m now using request handlers rather than controllers, my controller unit tests (

MockMvc

with standalone setup) are obviously failing 🙂 I’m trying to fix my unit tests but I’m struggling making things work. Seems like every request I’m making using

MockMvc

(without standalone steup this time) ends up with 404. When I run my app or my integration tests, everything works just fine, so I’m guessing it’s somehow related to the routes bean not being loaded to the app context. Failed to work around it though. Any ideas? am I missing something?

cpe

11/04/2019, 9:09 PM

Hey, I've got a question about the new Spring Router DSL. I am migrating an application from the traditional Mappings and struggling on a POST from a web form containing an array for a value, let's say like this:

<form name="users" action="POST">
<input type="text" name="someInfo">
<input type="text" name="users[name][0]">
<input type="text" name="users[surname][0]">
<input type="text" name="users[name][1]">
<input type="text" name="users[surname][1]">
</form>

data class InputForm(val someInfo: String, val users: Map<String, List<String>)

which could be wired like this:

@PostMapping("/users")
fun updateUsers(inputForm: InputForm) {
  // access input form data like "someInfo" and the map "user"
}

With the migration I have something like:

router {
  POST("/users", userController::updateUsers)
}

fun updateUsers(request: ServerRequest): ServerResponse {
  val inputForm = request.body<InputForm>()
  // do some stuff
  return ServerResponse.ok().render("success.html")
}

This is causing the following exception:

org.springframework.web.HttpMediaTypeNotSupportedException: Content type 'application/x-www-form-urlencoded;charset=UTF-8' not supported

What is the correct way to read the message in an automated way like it was possible with the traditional mapping? Or do I need to write a custom HttpMessageConverter?

joshr

11/05/2019, 2:49 AM

on this branch, though, i get the following:

joshr

11/05/2019, 2:50 AM

the only difference is that i split out the usercontroller and articlecontroller tests into separate test classes

Hullaballoonatic

11/05/2019, 7:05 PM

Is there a more succinct way to initialize properties of a configuration from a properties file than this?

@Configuration
class FooConfiguration {
    @Value("\${foo.bar}")
    lateinit var bar: String
}

This just seems really verbose, even compared to the java way, and I tend to prefer lazy delegation val over lateinit var for immutable properties like this.

nicholasnet

11/07/2019, 12:16 PM

Can you use coroutine in Spring JPA does it adds any benefit?

Hullaballoonatic

11/07/2019, 6:55 PM

I feel like if spring was written using kotlin originally, it would just use objects a lot instead of injection, but that's because i'm under the impression that beans are just singletons

Frodrigues

11/13/2019, 9:17 AM

Why don't they use directly the getters and instead use suppliers?

Dariusz Kuc

11/13/2019, 7:00 PM

hello! I'm trying to create configuration property metadata (https://docs.spring.io/spring-boot/docs/current/reference/html/appendix-configuration-metadata.html) for a map of objects, e.g.

myProps:
  configs:
    someName:
      x: "foo"
      y: 1
    anotherName:
      x: "bar"
      y: 2

that can be mapped to something like

@ConstructorBinding
@ConfigurationProperties(prefix = "myProps")
data class MyProperties(val configs: Map<String, MyCustomProperties>)

data class MyCustomProperties(val x: String, val y: Int)

This seems to work fine and properties are loaded correctly in the application context but I don't get any auto-completion in the yml/properties files for

MyCustomProperties

. Anyone knows whether it is possible to somehow provide the configuration metadata for the above that IntelliJ is able to understand?

Gary

11/14/2019, 4:59 AM

We're currently migrating our

Webflux

project to Co-routines. Loving the increased readability of co-routines and the simplicity of

async/await

, great job @sdeleuzeand team. But under the hood we're wondering should we expect any performance differences? If so in what circumstances is this likely to be evident?

soudmaijer

11/14/2019, 12:47 PM

Question, I was wondering how I can make use of the BeanDefinitionDsl in my WebMvcTest to replace my @TestConfiguration class. Any examples? Or stupid question 😉

thiagoretondar

11/14/2019, 9:35 PM

has anyone had this problem on

./gradlew bootJar

? (not using intellij, it is in my CI/CD)

* What went wrong: 
Plugin [id: 'org.springframework.boot', version: '2.1.4.RELEASE'] was not found in any of the following sources: 
 
- Gradle Core Plugins (plugin is not in 'org.gradle' namespace) 
- Plugin Repositories (could not resolve plugin artifact 'org.springframework.boot:org.springframework.boot.gradle.plugin:2.1.4.RELEASE') 
  Searched in the following repositories: 
    Gradle Central Plugin Repository

magisu

11/17/2019, 7:03 PM

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