Micronaut @RequestScope creates a new instance with each injection

I'm trying to create Micronaut bean with @RequestScope, but with each injection, there is a new instance created. I would expect it to create new instance only once per request.

Here is an example code:

@RequestScope
class RequestContext {
    var foo: String? = null
}

@Controller("/example")
class ExampleController(
    val requestContext: RequestContext,
    val exampleService: ExampleService
) {
    @Get()
    fun example() {
        requestContext.foo = "foo"
        exampleService.example()
    }
}

@Singleton
class ExampleService(
    val requestContext: RequestContext
) {
    fun example() {
        println(requestContext.foo) // prints nul instead of "foo"
    }
}

I have also tried wrapping RequestContext in Provider like here: micronaut @RequestScope - not creating bean per incoming http-request but it changes nothing.

What am doing wrong? How can I properly inject RequesScope bean into Singleton?

Micronaut Version: 4.5.1 Kotlin Version: 1.9.23

Solution

I could reproduce the behavior you describe.

I made your code work by following the pattern with getter/setter from this guide: Micronaut Scope Types

New version of class RequestContext with getter/setter:

import io.micronaut.runtime.http.scope.RequestScope

@RequestScope
class RequestContext {
    private var foo: String? = null

    fun getFoo(): String? = foo

    fun setFoo(foo: String) {
        this.foo = foo
    }
}

ExampleService:

import jakarta.inject.Singleton

@Singleton
class ExampleService(
    private val requestContext: RequestContext
) {
    fun example() {
        println(requestContext.getFoo()) // will now print "foo"
    }
}

ExampleController:

import io.micronaut.http.annotation.Controller
import io.micronaut.http.annotation.Get

@Controller("/example")
class ExampleController(
    private val requestContext: RequestContext,
    private val exampleService: ExampleService
) {
    @Get
    fun example() {
        requestContext.setFoo("foo")
        exampleService.example()
    }
}

An interesting observation (not part of the question) is that with a class like this:

import io.micronaut.http.HttpRequest
import io.micronaut.runtime.http.scope.RequestAware
import io.micronaut.runtime.http.scope.RequestScope

@RequestScope
class RequestContext : RequestAware {
    var foo: String? = null

    override fun setRequest(request: HttpRequest<*>?) {
        this.foo = "bar"
    }
}

code compiles, but setRequest is never called.

Making foo private with getter getFoo, setRequest will be invoked.

import io.micronaut.http.HttpRequest
import io.micronaut.runtime.http.scope.RequestAware
import io.micronaut.runtime.http.scope.RequestScope

@RequestScope
class RequestContext : RequestAware {
    private var foo: String? = null

    override fun setRequest(request: HttpRequest<*>?) {
        this.foo = "bar"
    }

    fun getFoo(): String? = this.foo
}