I have a spring boot application which is structured in hexagonal architecture (using clean architecture). So I have a sealed class which is at domain layer and I would not like to "mess" it with annotations. The issue is that I wouldn't like to expose the domain, but a resource class. I usually do it easily, creating a

toDomain()

function. But in this case, I don't know how to do it. Since I'm new to sealed class, maybe there is a solution which I haven't found... The sealed class (domain) is something like:

sealed class TypeInstruction(val type: String) {
    data class TypeOne(val isRequired: Boolean, val maxConcurrency: Short) : TypeInstruction(type = "typeOne")

    data class TypeTwo(val isRequired: Boolean, val maxAttemps: Short): TypeInstruction(type = "typeTwo")
}

And the resource is:

sealed class TypeInstructionResource(val type: String) {
    data class TypeOne(val isRequired: Boolean, val maxConcurrency: Short) : TypeInstruction(type = "typeOne")

    data class TypeTwo(val isRequired: Boolean, val maxAttemps: Short): TypeInstruction(type = "typeTwo")
}

Then an extended function:

fun TypeInstructionResource.toDomain() = when(type) {
    "typeOne" -> TypeInstruction.TypeOne(isRequired = isRequired, maxConcurrency = maxConcurrency)
    "typeTwo" -> TypeInstruction.TypeTwo(isRequired = isRequired, maxAttemps = maxAttemps)
    else -> /* */
}

But of course, the extended function does not recognize the "children" values, such as

isRequired

. Any suggestions?

Hi, I have a spring boot application and I'm trying to use kotlin serialization, i have set up my project according by the springs docs. So I trying to test my controller if it returns the expected result. If I boot my application the content is not as expected as I have some transient fields in my class but nonetheless the appear on the response. So I created a test to assert the expected body but I'm getting an error from fasterxml.jackson invalid definition. So far my guess is for some reason I'm not using kotlins seralization. The catch is my object has a field with type any and marked with contextual , so I tried to create my own serializers module based on kotlin.serialization docs/guides but I had no luck to be able to tell spring to use my own custom serializers module . Any idea ? Thanks In advance !

Say I have a class like this:

@RestController
class Foo(val bar: Bar, val baz: Baz = Baz("ding"))

bar

and

baz

will be autowired automatically as expected. But is it possible to disable autowiring for

baz

since it has a default value?

What's the best way to handle java.lang.OutOfMemory Error? Usually I let it propagate to the JVM/Docker container so the instance get’s killed / restarted. In my current application this error get’s caught in the Tomcat server of spring boot and I don't know why … any clues?

Anyone could give me feedbacks regarding https://ebean.io/ for spring book with kotlin ? It doens’t seem to be updated anymore but maybe it’s mature enough so it doesn’t.

Hello! I have a question regarding validation on web requests. We're validating the requestbody with some constraints, however, we have an additional constraint which needs access to the "referentie" parameter. We made it a value_parameter constraint, but unlike a nice 400 we normally can get back, with this, we get a 500. Is there a way to make this work?

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Is there any functional difference between

@PostMapping
suspend fun uploadFile(@RequestParam file: Mono<FilePart>)

and

@PostMapping
suspend fun uploadFile(@RequestParam file: FilePart)

other than maybe allow the former to not pass any value?

Hi, Any resources for spring boot + kotlin best practices and tutorials?

Hi everyone! I cannot add Ktor Client to Spring Boot Maven project. I’m trying to add Ktor Client to my Spring Boot Maven project but IntelliJ does not detect the dependencies. Already tried with reimporting maven dependencies, cleaning cache, mvn idea:idea and also creating another Spring Boot Maven project in a different machine and still doesn’t work. This is my pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="<http://maven.apache.org/POM/4.0.0>" xmlns:xsi="<http://www.w3.org/2001/XMLSchema-instance>"
         xsi:schemaLocation="<http://maven.apache.org/POM/4.0.0> <https://maven.apache.org/xsd/maven-4.0.0.xsd>">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demoproject</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demoproject</name>
    <description>demoproject</description>
    <properties>
        <java.version>1.8</java.version>
        <kotlin.version>1.6.10</kotlin.version>
        <ktor.version>1.6.7</ktor.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.module</groupId>
            <artifactId>jackson-module-kotlin</artifactId>
        </dependency>
        <dependency>
            <groupId>io.projectreactor.kotlin</groupId>
            <artifactId>reactor-kotlin-extensions</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-reflect</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-stdlib-jdk8</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlinx</groupId>
            <artifactId>kotlinx-coroutines-reactor</artifactId>
        </dependency>
        <dependency>
            <groupId>io.ktor</groupId>
            <artifactId>ktor-client-core</artifactId>
            <version>${ktor.version}</version>
        </dependency>
        <dependency>
            <groupId>io.ktor</groupId>
            <artifactId>ktor-client-cio</artifactId>
            <version>${ktor.version}</version>
        </dependency>
        <dependency>
            <groupId>io.ktor</groupId>
            <artifactId>ktor-client-serialization</artifactId>
            <version>${ktor.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
        <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <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>
        </plugins>
    </build>

</project>

And this is what I get in IntelliJ

Why does

@Component
class Foo {
    inline fun foo() {}
}

gives me

inline' modifier is not allowed on virtual members. Only private or final members can be inlined

How to use

@ Value

annotation in spring with Kotlin?

Anyone know how to retrieve the spring provided instance of an object mapper? I've tried autowiring as such

@Autowired
lateinit var builder: Jackson2ObjectMapperBuilder

Anyone know how to create bean for sealed classes. when i try using @Component annotation, it is throwing an error

Consider defining a bean of type '' in your configuration.

?

❓ How do we make non-blocking http post request in springboot? I have service A that is making about 100 or so request to service B. I want service A to make non-blocking http post request, that is make the http post request but don't wait for a response to make another one.

Hi everyone! How can I use Kotlin Serializer in a Spring Boot app?

Hi all, Any good resources/courses/books for reactive programming with kotlin (for backend) with spring boot ?

Has anyone been able to use AspectJ w/ Spring Boot and Kotlin? I’m trying to instrument a third party library, but for some reason it isn’t picking up my settings in

META-INF/aop.xml

. Also, when instrumenting Kotlin classes, it throws

org.aspectj.weaver.loadtime.Aj - com/company/<NameOfKotlinClass>MethodAccess java.lang.RuntimeException: Illegal type for StackMapType: 12

.

Releases on their way, related blog post https://spring.io/blog/2022/03/31/spring-framework-rce-early-announcement

I have a @Scheduled job that has a runBlocking { … } inside and performs cpu intensive work for multiple minutes. Due to this load, the actuator health endpoint becomes slow too, making the service seemingly unhealthy and thus triggers the cloud provider to restart the container. I tried isolating @Scheduled logic coroutine execution into a separate thread, but this does not help:

val pollingContext = Executors.newSingleThreadExecutor().asCoroutineDispatcher()
withContext(pollingContext) {
...
}

Anyone any ideas? Thanks!

Hey is there any coroutine version of web filters for kotlin?

Hello, I’m following this approach in order to get coroutine wrappers for Webflux WebFilters and I’m now trying to propagate MDC context in order to have it on my controllers. Im using

withContext(MDCContext())

whenever I put something in MDC, also using Mono

contextWrite(Context.of(coroutineContext[MDCContext.Key]?.contextMap ?: emptyMap()))

when calling WebFilter base

chain

Although this is not working and I suspect that is due to passing the coroutine context to the ReactorContext somehow I’m not doing it right

Hey how can I get reactor context when using suspend like controller handlers?

😞 https://github.com/spring-projects/spring-framework/issues/27345 Just bumping visibility of this isssue

Hello friends, may anybody help me about custom Query using JpaRepository ? I do use this query:

@Query("select id, email from User")
fun getAllIdsAndEmails(): List<Pair<Long, String>>

But sadly I get an error of

No converter found capable of converting from type [org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap] to type [kotlin.Pair<?, ?>]

Does Spring Data has any native support for

suspend

functions inside interfaces (like

ReactiveMongoRepository

or something similar, but for coroutines)?

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