Hi, I have a multi database setup in Spring Boot, each are in the

application.yml

file as

spring.datasource.[db1/db2].[options]

. Everything is working fine except I am not able to specify a separate schema.sql for each of them. I have tried by making a DataSourceInitializer bean but it is not getting executed (the bean is never even created). A normal

schema.sql

file works but is executed on all the databases.

@Bean(name = ["kvkDsInit"])
    fun dsInit(@Qualifier("kvkDataSource") dataSource: DataSource): DataSourceInitializer {
        val rdp = ResourceDatabasePopulator().apply {
            addScript(ClassPathResource("schema-kvk.sql"))
        }

        return DataSourceInitializer().apply {
            setDataSource(dataSource)
            setDatabasePopulator(rdp)
        }
    }

I would like to retrieve response body message for a given 400 status code when using the spring webclient. However, I can only find the error code and not the actual error message contained in the code. I am using following snippet. how to actually extract the response body in the 400 status response .

val retrievedResource: Mono<String> = myRequest
            .retrieve()
            .onStatus(HttpStatus::is4xxClientError) { Mono.error(RuntimeException("4XX Error ${it.statusCode()}, ${it.bodyToMono(String::class.java)}")) }
            .onStatus(HttpStatus::is5xxServerError) { Mono.error(RuntimeException("5XX Error ${it.statusCode()}, ${it.bodyToMono(String::class.java)}")) }
        .bodyToMono(String::class.java)
        return retrievedResource.share().block()

I’m trying to set up a Spring Boot Kotlin app with mysql/reactive. I’m following this simple example: . When I call http://localhost:8080/customers I get this 500 error though:

Failed to obtain R2DBC Connection; nested exception is java.util.NoSuchElementException: Flux#last() didn't observe any onNext signal

I pushed the project on this public repo: https://github.com/danygiguere/spring-boot-kotlin-reactive but basically, I have this config:

@Configuration
class Database : AbstractR2dbcConfiguration() {

    override fun connectionFactory(): ConnectionFactory
            = MySqlConnectionFactory.from(
        MySqlConnectionConfiguration.builder()
            .host("localhost")
            .username("root")
            .port(3306)
            .password("root")
            .database("reactive")
            .connectTimeout(Duration.ofSeconds(3))
            .useServerPrepareStatement()
            .build()
    )

}

my application.yml:

spring:
    r2dbc:
        url: r2dbc:<mysql://localhost:3306/reactive?autoReconnect=true&useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true&useSSL=false>
        username: root
        password: root

and the route in question is:

@RestController
@RequestMapping("/customers")
class CustomerController(val customerRepository: CustomerRepository) {

    @GetMapping
    suspend fun getAllCustomer() : Flow<Customer> = customerRepository.findAll().asFlow()
...

Update: one thing I just noticed is if I replace my getAllCustomer function with :

suspend fun getAllCustomer() : Flux<Customer> = customerRepository.findAll()

then I get this response:

{
  "scanAvailable": true,
  "prefetch": -1
}

Bonjour. After years of backend with Kotlin I may go back to Java - which I don’t mind - but the company has unfortunately a dumb process where you need to write Java / Spring code in a browser without code completion or quick fixes or documentation or stackoverflow. Do you have a good & simple Java/Spring project I can use to refresh my Java skills? (like putting the type first 🙂 )

After upgrading spring boot project to kotlin 1.7.20 different files are produced by the same gradle task (

bootJar

). I can see two tasks being executed with 1.7.20 -

jar

and

inspectClassesForKotlinIC

, which are not executed with 1.7.10. Anyone has some more information about this change?

is there a way to make every response object turn the fields to snake_case without having to

@JsonNaming

every data class?

I know this question has been asked before, but does using

@Cachable

with

suspend

functions still not work correctly? Everything I've found seems to indicate it doesn't work, but those findings are also a year or two old

would be very happy if someone can help

Anyone is using https://github.com/MarioAriasC/KotlinPrimavera? I've got some legacy projects using this library, but the artifacts were published to https://repo.spring.io/plugins-release/ and it's no longer available.

Hey guys, is it possible to load configurations with different implementation based on a property? eg:

myConfig:
  myList:
    - type: someType
      propertyA: someValue
      propertyA1: 32
    - type: otherType
      propertyB: otherValue
      propertyB1: abc

data class MyConfig(val myList: List<Config>)

interface Config {
    fun doStuff()
}

class SomeType(val propertyA: String, val propertyA1: Int): Config {
    override fun doStuff() {
        println("SomeType $propertyA")
     }
}

class OtherType(val propertyB: String, val propertyB1: String): Config {
    override fun doStuff() {
        println("OtherType $propertyB and $propertyB1")
     }
}

So this way I could do something like

class MyService(val myConfig: MyConfig) {
    fun serviceFunction() {
       myConfig.myList.forEach(Config::doStuff)
    }
}

Is it mandatory to have the variables in RequestDTO as nullable as jacken is throwing an exception if the value passed for the field is null. Is there a way to integrate bean validation or some alternative to have the fields non-nullable without the jackson throwing the exception?

Hi! i need help! how can i write SOAP client for reactive spring (webFlux), can you show me example for kotlin?

What is the best book/online education for learning Spring if you’re an experienced Kotlin developer? All suggestions welcome 🙂

Hi please tell me! Why? my entity not updated in db

if (checkEmailStatusVerification.first == description) { // it's ok
    verification.verificationState = description
    verificationRepository.run { save(verification) } // this code doesn't work
    throw EmailVerificationException("emailAlreadyVerified  ${verification.email}")
}

i am use

//reactive postgre
implementation("org.springframework.boot:spring-boot-starter-data-r2dbc")
runtimeOnly("io.r2dbc:r2dbc-postgresql:0.8.13.RELEASE")
runtimeOnly("org.postgresql:postgresql:42.5.1")

Hi, Whenever adding

spring-kafka-test

as a dependency I cannot run tests. Tests start to fail for following reason:

org.gradle.api.internal.tasks.testing.TestSuiteExecutionException: Could not complete execution for Gradle Test Executor 1.
	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.stop(SuiteTestClassProcessor.java:64)
	...
Caused by: java.lang.NoClassDefFoundError: org/junit/platform/launcher/TestExecutionListener
	at java.base/java.lang.ClassLoader.defineClass1(Native Method)
	...
	at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.processAllTestClasses(JUnitPlatformTestClassProcessor.java:97)
	at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.access$000(JUnitPlatformTestClassProcessor.java:79)
	at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor.stop(JUnitPlatformTestClassProcessor.java:75)
	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.stop(SuiteTestClassProcessor.java:62)
	... 18 more
Caused by: java.lang.ClassNotFoundException: org.junit.platform.launcher.TestExecutionListener
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
	... 50 more

This is what my gradle looks like:

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
import org.springframework.boot.gradle.tasks.bundling.BootJar

plugins {
    id("org.springframework.boot") version "3.0.0"
    id("io.spring.dependency-management") version "1.1.0"
    kotlin("jvm") version "1.7.22"
    kotlin("plugin.spring") version "1.7.22"
    `maven-publish`
    `java-test-fixtures`
}

group = "com.example"
version = "0.0.1-SNAPSHOT"
java.sourceCompatibility = JavaVersion.VERSION_17

repositories {
    mavenCentral()
}

dependencies {
    api("org.jetbrains.kotlin:kotlin-reflect")
    api("org.jetbrains.kotlin:kotlin-stdlib-jdk8")

    api("com.auth0:java-jwt:4.2.1")
    api("com.fasterxml.jackson.module:jackson-module-kotlin")
    api("io.github.microutils:kotlin-logging-jvm:3.0.4")

    api("org.springframework.boot:spring-boot-starter")
    api("org.springframework.boot:spring-boot-starter-actuator")
    api("org.springframework.boot:spring-boot-starter-data-mongodb")
    api("org.springframework.boot:spring-boot-starter-validation")
    api("org.springframework.boot:spring-boot-starter-security")
    api("org.springframework.boot:spring-boot-starter-web")
    api("org.springframework.kafka:spring-kafka")

    testFixturesApi("org.springframework.boot:spring-boot-starter-test")
    testFixturesApi("org.springframework.restdocs:spring-restdocs-mockmvc")
    testFixturesApi("org.springframework.security:spring-security-test")
    testFixturesApi("org.springframework.kafka:spring-kafka-test")
}

publishing {
    publications {
        create<MavenPublication>("maven") {
            groupId = project.group.toString()
            artifactId = project.name
            version = project.version.toString()

            from(components["java"])
        }
    }
}

tasks.getByName<BootJar>("bootJar") {
    enabled = false
}

tasks.getByName<Jar>("jar") {
    enabled = true
}

tasks.withType<KotlinCompile> {
    kotlinOptions {
        freeCompilerArgs = listOf("-Xjsr305=strict")
        jvmTarget = "17"
    }
}

tasks.withType<Test> {
    useJUnitPlatform()
}

Has anybody experienced similar issue?

Is it at all possible (or wise) to use a

typealias

as the return type of a

@Bean

? I just tried this, but it basically turns up as an unqualified

java.lang.String

, i.e. if there's another

@Bean

returning a

String

, they're in conflict:

typealias SpringProfile = String

@Configuration
class SpringConfig {
  @Bean fun activeProfile(@Value("\${spring.profiles.active}") name: String): SpringProfile = name
}

Did any of you tried Spring Boot 3 with Webflux and Kotlin using native GraalVM native build? Is it working properly?

hi, we upgraded to spring boot 3 and one of the things i cannot figure out .. is that some responses of our server changed from

application/json

to

application/cbor

(we have SOME responses that are explicitely cbor, but we don’t want all of the API to be) anyone knows how to tweak that.. or how to configure content negotiation or the like ? all tutorials i find for that are horribly outdated…

Hi, i have encountered a weird problem. I have a simple entity and im saving this entity in db with r2dbc using

R2dbcEntityTemplate

directly :

class MessageRepositoryImpl(private val template: R2dbcEntityTemplate) : MessageRepository {
    override suspend fun save(messageEntity: MessageEntity): MessageEntity =
        template.insert<MessageEntity>().usingAndAwait(messageEntity)
}

So far so good. now i want to refactor my entity's id to be a data class. for example: before:

@Table("messages")
data class MessageEntity(
    @Id
    @Column("id")
    val id: Int = 0,
}

after:

data class MessageId(private val value: Int) {
    fun toInt() = value
    override fun toString(): String = value.toString()
}

@InternalHubCoreApi
@Table("messages")
data class MessageEntity(
    @Id
    @Column("id")
    val id: MessageId = MessageId(0)
}

Now whenever i save something with above

save()

function it does not return the write result like before (i.e. the id which is on purpose 0 does not get returned with the actual value). But the entity is saved properly in db with proper (auto-increased) id, meaning if i search for it the result is correct. Has anyone encountered any similar problem? Thanks in advance for any help !!

Has anyone tried playing with Loom in Kotlin and Spring Boot? I’m following this blog post by Spring. But when I print the threads to the console, they aren’t virtual threads!

Is Virtual Thread: false | Thread[#38,http-nio-8080-exec-3,5,main]
Is Virtual Thread: false | Thread[#37,http-nio-8080-exec-2,5,main]
Is Virtual Thread: false | Thread[#41,http-nio-8080-exec-6,5,main]
Is Virtual Thread: false | Thread[#36,http-nio-8080-exec-1,5,main]
Is Virtual Thread: false | Thread[#39,http-nio-8080-exec-4,5,main]

The full code is here: https://github.com/aseemsavio/loomgraphql Here’s the code:

package com.asavio.loomgraphql

import org.apache.coyote.ProtocolHandler
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration
import org.springframework.boot.runApplication
import org.springframework.boot.web.embedded.tomcat.TomcatProtocolHandlerCustomizer
import org.springframework.context.annotation.Bean
import org.springframework.core.task.AsyncTaskExecutor
import org.springframework.core.task.support.TaskExecutorAdapter
import org.springframework.graphql.data.method.annotation.QueryMapping
import org.springframework.stereotype.Controller
import java.util.concurrent.Executors


@SpringBootApplication
class LoomgraphqlApplication

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

@Bean(TaskExecutionAutoConfiguration.APPLICATION_TASK_EXECUTOR_BEAN_NAME)
fun asyncTaskExecutor(): AsyncTaskExecutor? {
    return TaskExecutorAdapter(Executors.newVirtualThreadPerTaskExecutor())
}

@Bean
fun protocolHandlerVirtualThreadExecutorCustomizer(): TomcatProtocolHandlerCustomizer<*>? {
    return TomcatProtocolHandlerCustomizer { protocolHandler: ProtocolHandler ->
        protocolHandler.executor = Executors.newVirtualThreadPerTaskExecutor()
    }
}

@Controller
class PeopleController {

    @QueryMapping
    fun people(): List<Person> {
        println("Is Virtual Thread: ${Thread.currentThread().isVirtual} | ${Thread.currentThread()}")
        return listOf(
            Person("jdgahjdagdahjdg", "Jon", 25),
            Person("ddgahjdagdahjdg", "Snow", 26),
            Person("gdgahjdagdahjdg", "Arya", 23),
            Person("qdgahjdagdahjdg", "Stark", 21),
        )
    }

}

data class Person(val id: String, val name: String, val age: Int)

This is my build.gradle.kts file.

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

plugins {
    id("org.springframework.boot") version "3.0.1"
    id("io.spring.dependency-management") version "1.1.0"
    id("org.graalvm.buildtools.native") version "0.9.18"
    kotlin("jvm") version "1.8.0"
    kotlin("plugin.spring") version "1.8.0"
}

group = "com.asavio"
version = "0.0.1-SNAPSHOT"
java.sourceCompatibility = JavaVersion.VERSION_19

repositories {
    mavenCentral()
}

dependencies {
    implementation("org.springframework.boot:spring-boot-starter-web")
    implementation("org.springframework.boot:spring-boot-starter-graphql")
    implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
    implementation("org.jetbrains.kotlin:kotlin-reflect")
    implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
    testImplementation("org.springframework.boot:spring-boot-starter-test")
    testImplementation("org.springframework:spring-webflux")
    testImplementation("org.springframework.graphql:spring-graphql-test")
}

val preview = "--enable-preview"

tasks.withType<org.springframework.boot.gradle.tasks.run.BootRun> {
    jvmArgs = mutableListOf(preview)
}

tasks.withType<JavaExec> {
    jvmArgs = mutableListOf(preview)
}

tasks.withType<JavaCompile> {
    options.encoding = "UTF-8"
    options.compilerArgs.add(preview)
    options.compilerArgs.add("-Xlint:preview")
}

tasks.withType<KotlinCompile> {
    kotlinOptions {
        freeCompilerArgs = listOf("-Xjsr305=strict")
        jvmTarget = "19"
    }
}

tasks.withType<Test> {
    useJUnitPlatform()
}

Hello! I'm having some issues when trying to add custom headers to a

HttpServletResponse

within a suspend function. The approach we are using now is not good, so we would like to find a proper solution:

@GetMapping("/users")
suspend fun getUsers(//...parameters, response: HttpServletResponse): List<UsersResource> {
    val users = userService.searchBy(//parameters)
    response.addPaginationHeaders(users.size)
    return users
}

For instance,

addPaginationHeaders

will be changed only for example purposes, as below:

internal fun HttpServletResponse.addPaginationHeaders(size: Int) {
    val uri = ServletUriComponentBuilder.fromCurrentRequest().toUriString()
    setHeaders("X-Count", size)
    //...other params
}

So, suspend function doesn't work (throws

java.lang.IllegalStateException: No current ServletRequestAttributes

). Instead, we have to place the function body within a

runBlocking

to make it work.

suspend fun getUsers(\\...parameters, response: HttpServletResponse) = runBlocking {
    //same code as above
}

Has anyone experienced this issue? Is there any solution besides

runBlocking

?

Failed to initialize JPA EntityManagerFactory: Could not determine recommended JdbcType for `ar.com.school.management.models.entity.Subject` Hello everyone, I'm new with Kotlin and I'm trying to use it to make an app with Spring boot.I have just done the entities and anything else yet because I want to know if the app runs but I tried running it and it gives me the following exception "Failed to initialize JPA EntityManagerFactory: Could not determine recommended JdbcType for ar.com.school.management.models.entity.Subject"

package ar.com.school.management.models.entity

import com.fasterxml.jackson.annotation.JsonIgnoreProperties
import jakarta.persistence.*
@Entity
data class Career(@Id
              @GeneratedValue(strategy = 
              GenerationType.IDENTITY)
              @Column(name = "career_id")
              var id: Long?,

              var name: String?,

              @ManyToMany(cascade = [CascadeType.ALL], fetch = FetchType.LAZY)
              @JoinTable(name = "career_subject",
                  joinColumns = [JoinColumn(name = "career_id", referencedColumnName = "career_id")],
                  inverseJoinColumns = [JoinColumn(name = "subject_id", referencedColumnName = "subject_id")])
              @JsonIgnoreProperties("subjectCareers")
              var subjects: List<Subject>? = mutableListOf(),

              @OneToMany(mappedBy = "career")
              var students: List<Student>? = mutableListOf(),

              @ManyToMany(cascade = [CascadeType.ALL], fetch = FetchType.LAZY)
              @JoinTable(name = "career_teacher",
                  joinColumns = [JoinColumn(name = "career_id", referencedColumnName = "career_id")],
                  inverseJoinColumns = [JoinColumn(name = "teacher_id", referencedColumnName = "teacher_id")])
              @JsonIgnoreProperties("careers")
              var teachers: List<Teacher>? = mutableListOf()) {
constructor(): this(null,null,null, null, null)
}

hey channel. I’ve been trying to implement a POST with a ByteArray using this:

<http://requestBuilder.POST|requestBuilder.POST>(HttpRequest.BodyPublishers.ofByteArray(payload.httpBody.toByteArray()))

but in the controller I get: Resolved [org.springframework.web.HttpMediaTypeNotSupportedException: Content type ‘application/octet-stream;charset=UTF-8’ not supported] My Controller:

@RestController

@CrossOrigin

@RequestMapping(path = "/")

public class IngestionMockerController {

@PostMapping(value = "/")

public ResponseEntity<String> post(

@RequestBody Byte[] body) {

System.out.println("HttpRequestIngestionRequest = " + Arrays.stream(body).toArray());

return new ResponseEntity<>(HttpStatus.CREATED);

}

}

Please, could someone share an example of HTTP Client posting a ByteArray to a POST endpoint (@RequestBody Byte[] body)?

hey Channel. I am accustomed to inject beans using Springboot doing, for example:

@Autowired
private AccountMapper mapper;

I want to avoid of instantiate a HttpClient builder every time in my

@Component

class. Instead of do

val client = HttpClient.newBuilder().build()

every time, please let me know how to inject it using Kotlin.

Hey Channel! I need help! Test by kotlin and Spring Web Flux, service by react Code of AbstractClass with some initialization

@ActiveProfiles("test")
@ExtendWith(SpringExtension::class)
@SpringBootTest(classes = [ApiApplication::class], webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@AutoConfigureWireMock(port = 0)
@ContextConfiguration(initializers = [DBInitializer::class, KeyCloakInitializer::class])
abstract class BaseIntegrationTest {

    @Autowired
    lateinit var webClient: WebTestClient

    @Autowired
    lateinit var applicationContext: ApplicationContext

    @BeforeEach
    fun setUp() {
        webClient = WebTestClient.bindToApplicationContext(applicationContext)
            .apply(springSecurity())
            .configureClient()
            .build()
    }

    fun getTestJwt() = Jwt(
        "token",
        Instant.now(),
        Instant.now().plusSeconds(100),
        mapOf("testHeader" to "testHeader"),
        mapOf("clientId" to "TestExternalSystemCode")
    )

}

Code of TestMethod

val request = EmailVerificationStateRequestDto(cus = cusAX, email = testEmail)

        val response = webClient
            .mutateWith(
                mockJwt()
                    .jwt(getTestJwt())
                    .authorities(SimpleGrantedAuthority("emailVerificationState"))
            )
            .post()
            .uri("/emailVerificationState")
            .contentType(MediaType.APPLICATION_JSON)
            .body(Mono.just(request), EmailVerificationStateRequestDto::class.java)
            .exchange()
            .expectStatus().is2xxSuccessful
            .returnResult(EmailVerificationStateResponseDto::class.java)

and i got error log: https://kotlinlang.slack.com/files/T09229ZC6/F04K4PBAR24 please tell my why?

Try using a

lateinit

property:

@MockkBean lateinit var httpClient: HttpClient

Anyone have a working example of spring with picocli library? Seems like there is some issues on this: https://github.com/spring-io/start.spring.io/issues/1076