Hey, reminder that I will give a talk (description) at Kotlinconf next week Thursday April 13th at 4:15pm CEST room GRAANBEURSZAAL about how to scale to zero your Spring Boot Kotlin applications with GraalVM for cheaper and more sustainable Cloud hosting in a brand new talk. I will also share an update about related topics like CRaC support in Spring, and the second part of the talk will be about scaling to zero with Kotlin/Wasm and WASI, based on the work I currently do on KoWasm. If you can't come, it should be possible to watch it live on YouTube, you can subscribe to have a reminder .

Hi! Sorry, for a n00b question: I try to set up a fresh created spring boot 3.0.5 application in a Java Devcontainer in VS Code. Depending on adding “kotlin.compiler.jvm.target”: “17" in settings.json I get either

Cannot inline bytecode built with JVM target 17 into bytecode that is being built with JVM target 1.8. Please specify proper '-jvm-target' option kotlin(INLINE_FROM_HIGHER_PLATFORM)

or the versions other way around.. Any hints to get it to work?

How do we capture and set new entry to the cookies using webflux client when querying a server for subsequent requests to the server. Any example code snippets available to showcase the above usage? thanks in advance

Reminder : if you are at Kotlinconf, my Spring scale to zero talk starts in 10 minutes room Graanbeurszaal.

Otherwise you can watch it live on

Are there any plans/possibilities to support value class handling in SpEL? Trying to use it fails (probably due to using reflection and the value class generating a field with a randomized suffix?)

Not supported yet https://github.com/spring-projects/spring-framework/issues/28642. You can track https://github.com/spring-projects/spring-framework/issues/28638.

I have a

@Component

in which I want to run a suspend function on app start (

@PostConstruct

or

@EventListener

) and

@Scheduled

but this seem to only work on blocking methods. Is there a workaround?

I have this class in spring. If the block within

launch {}

throws an unexpected exception, the

populate()

method is never invoked again, even though its

@Scheduled

to recurr. Why is that?

@Component
class PrePopulatedStoreCache(
    private val contentManagerClient: ContentManagerClient,
): CoroutineScope, DisposableBean {
    private val cache:
            PrePopulatedCache<StoreByMerchantIdCacheKey, MinimalStore> =
        CaffeineBackedPrePopulatedCache.create(CacheConfiguration("all-stores"))

    private val job = Job()
    override val coroutineContext: CoroutineContext
        get() = job + Dispatchers.Default

    override fun destroy() = job.cancel()

    @Scheduled(fixedRate = 20, timeUnit = TimeUnit.SECONDS)
    private fun populate() {
        launch {
            <http://log.info|log.info>("Pre populating Store cache")
            contentManagerClient.getAllStoresV3()
                .onLeft { log.error("Unable to prepopulate Store Cache: $it") }
                .onRight { stores ->
                    cache.invalidateAll()
                    stores.forEach { cache.put(StoreByMerchantIdCacheKey(it.market, it.merchantExternalId), it) }
                    <http://log.info|log.info>("Populated cache with ${stores.size} stores in thread ${Thread.currentThread().name}")
                }
        }
    }

    suspend fun get(market: Market, merchantId: MerchantExternalId) =
        cache.get(StoreByMerchantIdCacheKey(market, merchantId))
}

data class StoreByMerchantIdCacheKey(val market: Market, val merchantExternalId: MerchantExternalId)

I am trying to download large file(in GBs), hence need to directly write to the disk(without memory). I am able to get it. However, I would also like to get the filename of the attachment I am downloading. Can somehow help? This code works..(but here I am manually setting the filename) . Is there a way to read the header onstatus successful perhaps?

https://github.com/spring-projects/spring-framework/pull/30402/files Is this the correct way to implement a renewTokenFilter using suspend style code?

is there a way to generate metadata about beans... similar to the configuration metadata, but manually generated in my libraries that use functional bean declaration to hint to intellij about which beans exist? maybe some of the AOT stuff has this going on under the hood?

Setting up a PoC using R2DBC, so I'm using

CoroutineCrudRepository

and just a simple

@RestController

. I'm trying to make sure I'm handling transactions properly. Using

@Transactional

isn't supported. I'm injecting a

TransactionalOperator

to my controller and using it like this:

@PostMapping("/")
    suspend fun create(@Valid @RequestBody info: Info): ResponseEntity<Model> =
            doInTransaction { repo.save(convert(info)).created() }

    @GetMapping("/{id}")
    suspend fun read(@PathVariable id: Id): ResponseEntity<Model> = doInTransaction { repo.findById(id).okOrNotFound() }

    @GetMapping
    suspend fun readAll(): ResponseEntity<List<Model>> = doInTransaction { repo.findAll().toList().ok() }

    private suspend fun <T> doInTransaction(block: suspend () -> T): T =
            transactionalOperator.executeAndAwait { block() }

Is using

executeAndAwait

like this correct?

Has anyone tried to use a

value class

as a PK for R2DBC? I wanted to create one to enforce UUID type:

@JvmInline
value class UUID(val uuid: java.util.UUID) {
    init {
        require(UuidUtil.getVersion(uuid) == UuidVersion.VERSION_TIME_ORDERED_EPOCH) {
            "UUID must be version 7"
        }
    }

    override fun toString(): String = uuid.toString()

    constructor() : this(UuidCreator.getTimeOrderedEpochPlus1())

    companion object {
        fun fromString(uuid: String): UUID = UUID(java.util.UUID.fromString(uuid))
    }
}

But the repo returns nothing for a

findById

w/ this. Works w/ a regular UUID.

I have this test:

@ExtendWith(SpringExtension::class)
@WebMvcTest(GetStoresByMarket::class)
internal class GetStoresByMarketTest {
    @Autowired
    private lateinit var mockMvc: MockMvc

    @MockBean
    private lateinit var getStoresByMarketAndConsumerId: GetStoresByMarketAndConsumerId
    @MockBean
    private lateinit var getStoresByMarketAndCategoryAndConsumerId: GetStoresByMarketAndCategoryAndConsumerId

    @Test
    fun `when market is unknown a client error should be returned`() {
        mockMvc.get("/v1/stores/asd") {
            param("consumerId", UUID.randomUUID().toString())
        }.andExpect {
            status { isBadRequest() }
        }
    }
}

the endpoint it tests is

suspend

, so the test fails with this output:

MockHttpServletRequest:
      HTTP Method = GET
      Request URI = /v1/stores/asd
       Parameters = {consumerId=[2d80c908-3699-4bf2-8eb8-ea1069de108a]}
          Headers = []
             Body = null
    Session Attrs = {}

Handler:
             Type = com.foo.http.v1.stores.GetStoresByMarket
           Method = com.foo.http.v1.stores.GetStoresByMarket#getStoresByMarket(String, String, String, Integer, Integer, Continuation)

Async:
    Async started = true
     Async result = org.springframework.web.server.ResponseStatusException: 400 BAD_REQUEST

Resolved Exception:
             Type = null

ModelAndView:
        View name = null
             View = null
            Model = null

FlashMap:
       Attributes = null

MockHttpServletResponse:
           Status = 200
    Error message = null
          Headers = []
     Content type = null
             Body = 
    Forwarded URL = null
   Redirected URL = null
          Cookies = []

Status expected:<400> but was:<200>
Expected :400
Actual   :200

How do I make sure I get the async result back in the test? I have tried variations of

runBlocking

and

runTest

to avail

How to validate a class not under my control in a web flux controller? I'm implementing PATCH and the controller function accepts a

@RequestBody @ValidJsonPatch patch: JsonPatch

I've created the validation annotation and constraint validator:

@Constraint(validatedBy = [JsonPatchValidator::class])
annotation class ValidJsonPatch(
    val message: String = "",
    val groups: Array<KClass<*>> = [],
    val payload: Array<KClass<out Payload>> = [],
)

class JsonPatchValidator : ConstraintValidator<ValidJsonPatch, JsonPatch> {
    override fun isValid(value: JsonPatch, context: ConstraintValidatorContext): Boolean { ... }
}

But the validator never gets invoked. I've added

_implementation_("org.springframework.boot:spring-boot-starter-validation")

to my dependencies and standard jakarta validation annotations work. edit: scratch that... standard validation annotations are also not working.

If for any reason, it's still necessary to keep

spring-boot-starter-web

, is it possible to use

Coroutines

by adding

spring-boot-starter-webflux

? will it work properly to have a

Flow

controller function for data stream?

Hi All, I'm having issues setting the Spring configuration-processor as an annotation processor. I added kapt to the kotlin-maven-plugin as it is in the image, but it is not generating the META-INF files for spring to autocomplete properties.

Hi everyone! I have a Spring Boot project with Kotlin, and I’m using the Redis OM Library (https://github.com/redis/redis-om-spring). I’m trying to do a query with Entity Streams (https://github.com/redis/redis-om-spring#-querying-with-entity-streams) but I have to configure the annotation processor (https://github.com/redis/redis-om-spring#-maven-configuration). I did that with kapt

<plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <version>${kotlin.version}</version>
                <extensions>true</extensions>
                <executions>
                    <execution>
                        <id>kapt</id>
                        <configuration>
                            <sourceDirs>
                                <sourceDir>src/main/kotlin</sourceDir>
                            </sourceDirs>
                            <annotationProcessorPaths>
                                <annotationProcessorPath>
                                    <groupId><http://com.redis.om|com.redis.om></groupId>
                                    <artifactId>redis-om-spring</artifactId>
                                    <version>0.8.0</version>
                                </annotationProcessorPath>
                            </annotationProcessorPaths>
                        </configuration>
                    </execution>
                </executions>
                <configuration>
                    <args>
                        <arg>-Xjsr305=strict</arg>
                    </args>
                    <compilerPlugins>
                        <plugin>spring</plugin>
                    </compilerPlugins>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-allopen</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                </dependencies>
            </plugin>

But I’m getting this error:

exception java.lang.NoSuchFieldException is never thrown in body of corresponding try statement

And this is the generated class

public final class UserInfoHash$ {
  public static MetamodelField<UserInfoHash, String> _KEY;

  static {
    try {
      _KEY = new MetamodelField<UserInfoHash, String>("__key", String.class, true);
    } catch(NoSuchFieldException | SecurityException e) {
      System.err.println(e.getMessage());
    }
  }
}

Can someone help me with this please?

Hi all, hope you’re having a great day! I have a test as follows:

@SpringBootTest(classes = [TestConfig::class])
class OrderTests: OtherClass {
    val orders = listOf<Order>() //this is just a representation - it's actually part of OtherClass
    
    @Import(Application::class)
    class TestConfig {
        // I'd like to pass it in here
        @Bean
        fun orderRepository() = FakeOrderRepository(orders)
    }

    @Test
    fun `works now`() {
        println("yay")
    }
}

I have a Spring test where I’m replacing a bean. However, I’d like to supply a specific parameter (

orders

) when creating the bean. The problem is that

orders

is part of another class that is implemented by `OrderTests`:

OtherClass

. I played around with it and can’t think about a way of how I could pass that into the bean. The problem is that it’s quite crucial and that there’s no way to change the way the

orders

are set up in

OtherClass

. The easiest (from a vanilla point of view) would be to mark

TestConfig

as

inner class

, but that’s not compatible with Spring. Do you have an idea? Thanks in advance! 👋

Hi Kotlin/Spring developers, I encountered an issue when using WebClient to send request in a forEach in a scheduled tasks. But the scheduled task is stopped due to a wired exception similar to this:

~.client.ExchangeFunctions: Cancel signal (to close connection)

....

kotlinx.coroutines.JobCancellactionException: MonoCoroutines was cancelled.

and the last exception is thrown again and again till time out, what we want is if there is an exception in one iteration(we used try/catch to handle it), and move to the next iteration. Now the result it stopped the whole scheduled task. Any idea? https://stackoverflow.com/questions/63472729/cancel-signal-close-connection-what-could-be-the-cause

I'm happy to announce the first release of interfAIce, a new open source library written in Kotlin interfAIce is an automatic proxy generation library that lets you harness the power of ChatGPT into your applications - just by defining an interface. The auto-generated proxy will query the OpenAI api based on your method definition(name, parameters, returnType, etc) and return the LLM's response in any Kotlin/Java type you want! The library also comes with support for: • spring boot • Kotlin Coroutines & Java Reactor If you're interested, check out my blog post for more Slack Conversation

Hey Kotlin/Spring developers. I have a basic question about "best practices" in Kotlin/Spring. Past Java experience and "best practice" guidance has steered me towards always creating a separate interface and implementation for every service. I understand the benefits of interfaces, but I'm wondering if they're unnecessary and just extra overhead in the Kotlin projects I'm working on. In our case, every interface only ever has a single implementation. The implementation's public signature matches the interface exactly. In unit tests, if we need mocks, Mockk (and I think most any other mocking framework) easily handles creating mocks for concrete classes and shows no performance difference between that and mocking an interface. They currently appear to add no benefits to our project, and do come with a small implementation cost. Is there a solid reason I should be leading my team to using interfaces anyway, or is this a good case where we drop them.

How can one easily build an url having queryParameters if I have the queryParams in a simple

val params= mapOf("foo" to "bar")

, how can I pass it to an

UriComponentBuilder

?

Hi everyone. I notice that in Java you can use something like

SpringApplication.from(xxxx::main).with(yyyy.class).run(args)

to copy the configuration of your main xxxx SpringBootApplication class and extend it with the configuration class yyyy.class Specifying xxxx::main in Kotlin don't want to resolve in Intellij, but for Java it works. The argument for the

.from

method is of type

ThrowingConsumer

which neither the Java main or the Kotlin main functions match, yet it works for Java, but not Kotlin. I guess the broader question is, can you get a function reference to

fun main(..)

and how do you use it?

What do I need for this nice block syntax seen at https://medium.com/backyard-programmers/kotlin-spring-boot-unit-testing-integration-testing-with-junit5-and-mockk-a2977bbe5711 I only can say status().isOk(), and I cannot use the content block.

Hi , does kotlin’s

context class

work well with spring ? Because of some context requirement , I have to mark my spring bean

context

:

context(IConfig)
@Named
class MyService (...) {

   val config = SomeBuilder().build() // it needs IConfig context
}

test :

internal class MyServiceTest : AbstractCoreTest()  {

  @Inject
  private lateinit var service: MyService
  
  // do tests
}

It compiles OK , but when executing , it throws :

java.lang.IllegalStateException: Failed to load ApplicationContext for [MergedContextConfiguration@484876a1 testClass = foo.MyServiceTest, locations = ["classpath:core.xml"], classes = [], contextInitializerClasses = [destiny.TestAppInit], activeProfiles = [], propertySourceLocations = [], propertySourceProperties = [], contextCustomizers = [], contextLoader = org.springframework.test.context.support.DelegatingSmartContextLoader, parent = null]
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext

…

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'myService' defined in file [.../MyService.class]: Unsatisfied dependency expressed through constructor parameter 0: No qualifying bean of type 'IConfig' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}

Is there a better way to solve this ? Thanks. (Kotlin 1.8.21 , Spring 6.0.9)

This message was deleted.