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Hello everyone. I spent the last few weeks learning Spring boot with Kotlin, but I’m stuck at the point where I can’t figure out how to implement the spring security jwt

stateless

authentication. The front end will be an SPA.

Anyone knows an easy tutorial that could help me ?

I’ve tried many ones but it was too complicated for a spring boot rookie like me.

I have 4 different endpoints in my Controller that all have the same 7 headers. Is there a way to avoid boilerplate code, i.e. repeating each header declaration for every endpoint?

Hi I have a problem with serialization enum using kotlin, spring, jackson. I made a stack overflow question so i wont copy paste it, maybe someone of you will know how to solve it. https://stackoverflow.com/questions/72700370/spring-boot-serialize-kotlin-enum-by-custom-property.

are there recommendations for moving from Java to Kotlin for hibernate? in particular, i'm trying to get the best null safety i can get... There is this https://medium.com/swlh/defining-jpa-hibernate-entities-in-kotlin-1ff8ee470805 but...my issue is, if i set nullable=false...that should be a @nonnull object, because i know it's an impossibility for it to happen in my scenarios. How can I get that though? do I need to use lateinit here?

I'm getting the following when trying to use JPA, spring, noargs, all-open.

Class 'CmcSbsbSubsc' should have [public, protected] no-arg constructor

this doesn't seem to be a compiler issue though...it compiles fine through maven. Does this mean this intention is wrong because we are doing noarg at annotation time? and i should tell IDEA to ignore that warning on the class name?

@Entity
@Table(name = "CMC_SBSB_SUBSC", schema = "FACETCOR")
data class CmcSbsbSubsc(
    @Id
    @Column(name = "SBSB_CK", nullable = false)
    val sbsbCk: Long,

    @Column(name = "SBSB_ID", nullable = false)
    val sbsbId: String
)

i'm running into an issue with JPA/hibernate and the spring jpa plugin, which is supposed to generate no-arg ctors for each class. It does...BUT, it does not do so for composite key classes. for example. I understand why this is..because no-args is looking for particular annotations. but what annotation can I mark here, to not conflict with anything in hibernate, but get no-args to see it? Short of making my own annotation EDIT: i think i need

@Embeddable

to get it to work. hopefully that doesn't interfere

@EqualsAndHashCode

class CmcMepePrcsEligId(

val memeCk: Long,

val cspdCat: String

) : Serializable {

companion object {

private const val serialVersionUID = 1L

}

}

huh. nope. I just ran into this issue: https://youtrack.jetbrains.com/issue/IDEA-240844

📢 hello folks! We are in process of updating the Spring-Kotlin tutorial in our documentation. I think it’s a good time to ask for the feedback from the community. We don’t plan to make it super-comprehensive though, the goal is rather to show how to get started with Kotlin in the Spring projects and cover some of the obvious use cases. Here I have the first draft. Please let me know what do you think about in the thread 🧵

regarding my other thread reply, i'm currently getting a 'smart cast is impossible because xyz is a property that has an open or custom getter'. I am using the all-open plugin. is there a workaround for this? is it just a consequence of JPA, or something else? i mean, a workaround to still get smartcasts

hi there did anyone update SB recently? (I`m moving from 2.5 to 2.7) Receiving

No default constructor found; nested exception is java.lang.NoSuchMethodException

on configuration class loading(with sb 2.6 and 2.7) that have been properly loaded(with SB 2.5) with constructor injection have I missed some important about bean configuration process updates?

hi guys, i am getting

finishConnect(..) failed: Connection refused: /[0:0:0:0:0:0:0:1]:80; nested exception is io.netty.channel.AbstractChannel$AnnotatedConnectException: finishConnect(..) failed: Connection refused: /[0:0:0:0:0:0:0:1]:80
org.springframework.web.reactive.function.client.WebClientRequestException: finishConnect(..) failed: Connection refused: /[0:0:0:0:0:0:0:1]:80; nested exception is io.netty.channel.AbstractChannel$AnnotatedConnectException: finishConnect(..) failed: Connection refused: /[0:0:0:0:0:0:0:1]:80

from a rather simple springboot-kotlin code. Has anyone encountered this? Thanks in advance 🙂

Hi, is anyone with experience with

spring-boot-starter-data-cassandra-reactive

and

CoroutineCrudRepository

? I’m quite struggling with using reading user-defined type (UDT), writing to the table works fine. Sample repo here

🤯 I'm having trouble with Kotlin + Spring magic (

@Transactional

) in following code:

class MyBoolean(var value: Boolean) {
    fun get(): Boolean = value
}

abstract class Foo {
    private val _hasError = MyBoolean(false)                                // <- line 16
    val hasError: Boolean get() = _hasError.get()
}

@Component
class MyFoo : Foo() {
    @Transactional
    fun doFoo() {
    }
}

class FooTest : SpringTest() {
    @Autowired
    lateinit var foo: MyFoo

    @Test
    fun `is null`() {
        assertThat(foo.hasError).isFalse                                    // <- line 33
        foo.doFoo()
    }
}

code/test above throws exception

java.lang.NullPointerException: Cannot invoke "com.bitsafe.behi.admin.projections.MyBoolean.get()" because "this._hasError" is null

at Foo.getHasError(FooTest.kt:16)
at <http://FooTest.is|FooTest.is> null(FooTest.kt:33)

which doesn't make sense as

_hasError

should never be

null

? If I remove

@Transactional

from

doFoo

method everything works as expected. What's going on? BTW problem also disappears if I put stuff from

abstract class Foo

directly into

class MyFoo

(which I don't want).

Does anyone know if it's possible to use JSR-380 validation without being required to have all my class constructor parameters be nullable? Meaning can I do this

@Entity

class Test(@field:NonNull val param: String)

or do I have to do

@Entity

class Test(@field:NonNull val param: String?)

Hello everybody! I am new in spring boot. I would like to know if you have some tools to generate openapi json documentation during the build of spring boot project? I would like to integrate autogeneration of the json file in github action ci. Thank you

Hello, I am a big fan of Spring, but an even bigger fan of Kotlin Multiplatform, especially the common code part. However, for entities and persistence this is not possible, since the annotations are JVM-world only. What would be an optimal way to share the entities between platforms? One way would be to just accept it and write

fromDataEntity

and

toDataEntity

helper functions for every common data class which is to be persisted. But that is a lot of boilerplate I suppose. Any other ideas?

Another question. Does

RepositoryRestResource

not work with

UUID

? I am getting "EntityRepresentationModel not found!": I have a very simple Entity and Repository:

@Entity()
class Account(
    @Id var id: UUID,
    var name: String
)

@RepositoryRestResource(path="accounts", collectionResourceRel = "accounts")
interface AccountRepository : CrudRepository<Account, UUID> {
}

@Bean
fun initializeDatabase(accountRepository: AccountRepository) = ApplicationRunner {
    accountRepository.save(Account(id = UUID.randomUUID(), name = "Test"))
    <http://logger.info|logger.info>("Initialized test data")
}

And when I run the application I get a nice HATEOS response:

{
  "_embedded": {
    "accounts": [
      {
        "name": "Test",
        "_links": {
          "self": {
            "href": "<http://localhost:8080/accounts/4c12f420-6189-4abd-a970-573ba2e0ca23>"
          },
          "account": {
            "href": "<http://localhost:8080/accounts/4c12f420-6189-4abd-a970-573ba2e0ca23>"
          }
        }
      }
    ]
  },
  "_links": {
    "self": {
      "href": "<http://localhost:8080/accounts>"
    },
    "profile": {
      "href": "<http://localhost:8080/profile/accounts>"
    }
  }
}

But when I go to that URL I get a 404 and an error in the console saying:

Resolved [org.springframework.data.rest.webmvc.ResourceNotFoundException: EntityRepresentationModel not found!]

It works with a Long as ID. So that is confusing. EDIT: I need to add

@Column(columnDefinition = "BINARY(16)")

to the entity ID.

Hello! Has anyone achieve to made the

@Transactional

work using

suspend

functions? (using sql db)

Hi all, I noticed that by default, the Spring annotation @ConfigurationProperties is not added to the list of all-open annotations (which I think is here: https://github.com/JetBrains/kotlin/blob/cca2680c7f1c3e690a9f4a56f13449f20ebfaa6d/plugins/allopen/allopen-cli/src/AllOpenPlugin.kt), would it be useful to add it? We've had some issues with it and adding it manually to our all-open had solved it:

<option>all-open:annotation=org.springframework.boot.context.properties.ConfigurationProperties</option>

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Hi folks, does anyone knows if i can acces in spring-rsocket @connectMapping the setupPayload ? I get the error:

Payload content is missing

if try to add @Payload annotation with @connectMapping. Per my understading from docs: quote connectMapping this should work (i guess) (Snippet in thread). Thanks for any answers ins advance !

I'm coming from the rails world and have been reading up on spring, is there a background job runner library I can use along the lines of ActiveJob & (sidekiq | goodjob) in spring? I have looked at spring batch but I'm not seeing a background job executor process. I did find jobrunr though, so I'm curious what others are using to run background jobs?

I’m learning spring boot with Kotlin and I’m trying to do a WebClient call with Flux. I have these methods in a controller:

@GetMapping("/slow-service-users")
    fun getAllUsers(): List<User?>? {
        Thread.sleep(2000L) // delay
        return userRepository.findAll()
    }

    @GetMapping(value = ["/users-non-blocking"])
    fun getUsersNonBlocking(): Flux<User?>? {
        <http://logger.info|logger.info>("Starting NON-BLOCKING Controller!")
        val userFlux: Flux<User?> = WebClient.create()
            .get()
            .uri("<http://localhost:8080/slow-service-users>")
            .retrieve()
            .bodyToFlux(User::class.java)
        userFlux.subscribe { user -> <http://logger.info|logger.info>(user.toString()) }
        <http://logger.info|logger.info>("Exiting NON-BLOCKING Controller!")
        return userFlux
    }

/slow-service-users

returns a proper response. But when I call

/users-non-blocking

, I get this error:

"org.springframework.web.reactive.function.client.WebClientResponseException: 200 OK from GET <http://localhost:8080/slow-service-users>; nested exception is org.springframework.web.reactive.function.UnsupportedMediaTypeException: Content type 'application/json' not supported for bodyType=com.example.app.models.User

How can I fix this

Content type 'application/json' not supported for bodyType

error ? The project repo is here: https://github.com/danygiguere/springboot-kotlin-example. The user model is:

@Entity
class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    var id: Long? = null

    var username = ""

    @Column(unique = true)
    var email = ""

    var password = ""
        @JsonIgnore
        get() = field
        set(value) {
            val passwordEncoder = BCryptPasswordEncoder()
            field = passwordEncoder.encode(value)
        }

    fun comparePassword(password: String): Boolean {
        return BCryptPasswordEncoder().matches(password, this.password)
    }

    val firstName: String = ""

    val lastName: String = ""

    @JsonManagedReference
    @OneToMany(cascade = [(CascadeType.ALL)], orphanRemoval = true, fetch = FetchType.EAGER)
    @JoinColumn(name = "userId", referencedColumnName = "id")
    var posts: List<Post>? = null
}

Hello everyone. I’m trying to implement Kotlin coroutines within a project as per this article https://spring.io/blog/2019/04/12/going-reactive-with-spring-coroutines-and-kotlin-flow. However wherever I see client.execute() or client.select(), IntelliJ highlight execute in red. All I can see when I hover is this message Unresolved reference: execute. I think I have a missing gradle package. I have these regarding couroutines:

mplementation("org.springframework.boot:spring-boot-starter-webflux:2.7.3")
	implementation("org.springframework.boot:spring-boot-starter-data-r2dbc")
	implementation("org.springframework.data:spring-data-r2dbc:1.5.2")
	implementation("io.r2dbc:r2dbc-spi:1.0.0.M6")
	implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core")
	implementation("org.jetbrains.kotlinx:kotlinx-coroutines-reactor")

Anyone can see what I’m missing ?

Using Spring and Java I’m doing a restTemplate call:

restTemplate.exchange(uri, <http://HttpMethod.POST|HttpMethod.POST>, request, Response.class);

the problem is that the response is an array that contains an object. How could I make the Response class to return an array ? I tried doing:

restTemplate.exchange(uri, <http://HttpMethod.POST|HttpMethod.POST>, request, ArrayList<Response>.class);

(then I would not need to return the class as an array) But I can only do

ArrayList.class

. It won’t take the

<>

can i use

jakarta.annotation-api

.Generated on a low jdk version? (8) ?

Today I discovered that in Kotlin Spring (JVM) when I define a

@Service

with a method that declares default parameter values and then call the service from another

@Component

not supplying a value, there is a NoSuchMethodError thrown. Apparently Spring creates a (Java) proxy for the service which does not support default parameter values (not supported in Java). Is there a solution for this problem?