Can I somehow use suspending functions with Spring Quartz scheduler without

runBlocking {}

?

Request handler methods do not support

value class

es as arguments. i’m seeing this exception (stacktrace in thread):

IllegalArgumentException: object is not an instance of declaring class

Hey guys. Does anybody know how I can define and use a method in a DTO? The DTO is proxied by Spring data projection (by a native query). It seems to not recognize my method I defined in the interface.

Null return value from advice does not match primitive return type for: public abstract double <DTONAME>.<METHOD>()

Hi. Are we supposed to be able to return a kotlin Sequence from a spring-data query? Not finding much on Google...

Hey guys, I was wondering if there were any examples with Spring R2dbc + postgres interval data type, I am trying to find a way to read and write interval values but can’t find anything so far

How well does Spring support following the official Kotlin coding convention for directory structure? Does package scanning still work correctly using a pure Kotlin directory/package structure?

Is there anyway in spring + kotlin do to a mixed constructor where you have e.g.

@Service
class MyClass(
   myService: MyService, // autowired
   helper: Helper = Helper("defaultValue") // just get default value but somebody could override this in e.g. tests
)

?

Hey Spring users, I am creating the Klogging logging library in Kotlin. There is also an SLF4J binding and a Spring Boot Starter. Currently it supports Splunk, Graylog and Seq destinations directly. Let me know if you try it and if you find it useful (or not!).

i’m sure i’m just doing something silly, but i’ve got a spring boot project containing:

src/main/kotlin/com/foo/Blah.java
src/main/kotlin/com/foo/bar/WebController.kt

WebController instantiates and uses a Blah. at compile time, no issues. when i start the app with

gradle bootRun

- at runtime i get:

java.lang.NoClassDefFoundError: com/foo/Blah

i shouldn’t have to do anything special to make sure the java classes are on the classpath, right?

When running spring webflux app with kotlinx.serialization enabled I get

500 Internal Server Error

when there is a problem with deserialization (e.g. missing key in the request data). When using jackson serialization with the same data the error is

400 Bad Request

. Can I somehow configure the returned error for kotlinx.serialization?

@Emil Kantis https://kotlinlang.slack.com/archives/C0B8ZTWE4/p1634020951040300?thread_ts=1633847081.037300&cid=C0B8ZTWE4 interesting example, I guess I never tried with

Int

. with

String

you get an exception, I guess it might be the compiler unwrapping

Int

to

integer

(compared to

Integer

), where

null == 0

also in plain java. your second example needs a bit of configuration of the kotlin module,

jacksonObjectMapper().registerModule(KotlinModule(nullIsSameAsDefault = true))

(moved we don’t spam uninterested people)

Hi all, got a spring/kotlin specific question. What is the best way to deal with parameters that might be nullable in some controllers and non null in others? For example; I’ve written a converter for the

CountryCode

which converts a String to a CountryCode. If this value is not there or invalid it will return a 400 “InvalidParameter”. But if I make the value nullable, the value should just be null when it’s missing or invalid.

@RequestParam(value = "country") countryCode: CountryCode // Should throw an exception when invalid or missing
@RequestParam(value = "country") countryCode: CountryCode? // Should be null when invalid or missing

Is there a way to create separate converters for the nullable and non nullable implementations? (Probably not because it’s not actually a different type?) By just returning null in the converter I will get:

Required request header 'country' for method parameter type CountryCode is present but converted to null

Which feels like its leaking some information to the outside world which they don’t need to know about. I could make the param an

Optional<CountryCode>

for the nullable case, map the message of the exception or do the mapping from String to CountryCode in the controller function. But those options all feel less nice. Is there a completely different solution I didn’t think of?

I'm creating a REST-client with a

@Cacheable

method. Since

@Cacheable

is broken for suspend functions, I tried to do this with reactor-types for the specific method instead. Looks something like this:

@Cacheable("my-cache")
fun fetchThing(key: String): Mono<Thing> = 
  webClient.get("/thing/{key}", key)
    .retrieve()
    .bodyToMono()

Now, in the code where I use this. I want to bridge back into awesome realm of suspend (😉), so I do:

restClient.fetchThing(key).awaitSingle()

. However, it seems that invoking

awaitSingle()

twice on a

Mono

created this way will actually cause the webrequest to fire again, instead of lazily returning the already existing result in the

Mono

.. Does anyone know the proper way to get back to suspend functions after creating a Mono like this? Should I map the mono to a lazy mono of first result or something?

I have an issue with kotlin

Result

and AOP

package com.example.demo

import org.aspectj.lang.ProceedingJoinPoint
import org.aspectj.lang.annotation.Around
import org.aspectj.lang.annotation.Aspect
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication
import org.springframework.stereotype.Component
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RequestParam
import org.springframework.web.bind.annotation.RestController

@SpringBootApplication
class DemoApplication

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

@RestController
@RequestMapping("/test")
class TestController(val repository: TestRepository) {
	@GetMapping
	fun test(@RequestParam(defaultValue = "#{{}}") list: List<Int>) =
		repository.getList(list)
				.getOrElse { list }
}

@Component
class TestRepository {
	fun getList(list: List<Int>): Result<List<Int>> = runCatching { throw RuntimeException("Error") }
}

@Aspect
@Component
open class MyOhMy {
	@Around("within(com.example.demo..*Repository+)")
	fun aspect(joinPoint: ProceedingJoinPoint): Any? =
			joinPoint.runCatching {
				proceed()
			}.getOrThrow()
}

issue is that

getOrThrow

in the aspect actually throws, while I would expect to return a

Result<Failure

more in thread

Has anyone managed to get a WebFlux controller working with value classes? I get the error

object is not an instance of declaring class

when trying to use a

@PathVariable

that is a value class.

🧵 - Where do y’all put your extension functions? I have some protobufs in my gRPC service. Some people are writing extension functions for these protos in the

@Service

component, some in models.kt. I’ve seen extensions.kt in other places… Wdyt?

when validating a controller using kotlin/spring, how would you validate that a date is after the other? I tried creating a data class and having an

@AssertTrue

in the data class, but I'm getting an unused function error (🧵 )

Talk about guys! Do you happen to have any material on the differences between Spring and Ktor? Please

Guys, I have a property in

application.yaml

which is set like

maxRetries: ${MAX_RETRIES:3}

where

MAX_RETRIES

is set as an env var. I'm using Spring to map the properties using

@ConfigurationProperties

. This particular variable is

UByte

and since it is kotlin, Spring can't map it. Any clues how to convert it properly?

Hey guys, what’s the preferred way to use configuration-metadata-annotation-processor with kotlin? As KAPT is scheduled for deprecation and increases build time … ?

Out of curiosity, did anyone of you play around with supplying lambdas as beans? I’m talking about the following:

@Configuration
class MyConfig {
    @Bean
    fun sendAnEmail(emailPublisher: EmailPubSubPublisher) = sendAnEmailLambdaVersion(emailPublisher)
}

fun sendAnEmailLambdaVersion(emailPublisher: EmailPubSubPublisher): (SomeEmail) -> Mono<String> =
    { email: SomeEmail -> emailPublisher.send(email) }

sure it works, but throwing

@Bean

on the function directly would be ofc more elegant, but I’m currently making no progress in that direction. Does anyone have any experience with that? Thanks! 🙂

FYI I am collaborating with Kotlin team to tentatively remove

kotlin-reflect

dependency from Spring Boot 3 applications and use a more lightweight Kotlin reflection alternative, I will share more on that as we make progress.

does this ring a bell for anybody?

anyone could tell me what’s wrong with this

existingUser.copy(username...

here :

package com.example.app.controllers

import com.example.app.models.User
import com.example.app.repositories.UserRepository
import org.springframework.http.HttpStatus
import org.springframework.http.ResponseEntity
import org.springframework.web.bind.annotation.*
import java.util.*
import javax.validation.Valid

@RestController
@RequestMapping("/api")
class UserController(private val userRepository: UserRepository) {

    @PutMapping("/users/{id}")
    fun updateUserById(@PathVariable(value = "id") userId: Long,
                          @Valid @RequestBody newUser: User): ResponseEntity<User> {
        return userRepository.findById(userId).map { existingUser ->
            val updatedUser: User = existingUser.copy(username = newUser.username)
            ResponseEntity.ok().body(userRepository.save(updatedUser))
        }.orElse(ResponseEntity.notFound().build())
    }

I get this compiling error:

Unresolved reference: copy

and then would it be possible to load them (optionnaly) within the controller ?

Hej! If I have a SQL table that defines such a table

CREATE TABLE elements (
  id SERIAL PRIMARY KEY,
  resource_id VARCHAR(50) UNIQUE DEFAULT uuid_generate_v4(),
  name VARCHAR(100) NOT NULL
)

and a class like

@Entity
@Table(name = "elements")
data class Element(
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column
    var id: Int?,
    @Column
    var resourceId: String?,
    @Column
    var name: String?
)

How can I only create new objects via

val elem = Element(name="foo")

and let the rest be automatically created via JPA/Hibernate Is that even possible in my case? Do I just need different constructors then?

Hey everyone, I'm looking for suggestions, as a part of a database management systems course in my engineering college, I've to build a mini project to demonstrate the various concepts like create, update and query on the database etc. I've decided to build a dog adoption system. Basically, there are two types of users, 1). admin - posts the details of the dogs, maintains the record of users and dogs, processes the requests of dogs by the user, etc. 2). user- creates a profile, views a list of dogs, requests for dogs and waits for the confirmation, etc(I've attached the ER diagram below, any suggestions are welcomed). I've thought of using MySQL as the database management system, Spring Boot (Spring MVC, Spring Security, Thymeleaf, JDBC API and optionally Vaadin) I don't think I can use an ORM or API's like Spring Data JPA and I'll have to work with pure SQL queries and statements. I'm finding it hard to look for examples and resources for the same, any help would be appreciated. Thanks.

Hello, I was wondering if I could replace the usual Spring MVC

@Scheduled

annotation with Reactive Spring + Webflux’s

Flux.interval

method. Is this approach sane? Thanks in advance!