HI, I am quite new to kotlin. I have currently an...

# getting-started

[huehnerlady]

HI,

I am quite new to kotlin. I have currently an generated Java interface containing spring Requestmapping annotations and extend this in my kotlin project.
This works fine and the annotations are picked up and processed.
When I generate the same interface as a kotlin interface though, these annotations seem to be ignored.

Do I have to configure something to make this work?

[Margarita Bobova]

@huehnerlady Hello! Could you please share the code example?

[huehnerlady]

@Margarita Bobova thanks for asking.

So when I have a spring @RestController class and in there a method test like so:

@RequestMapping(
            value = ["/test/{testId}"],
            produces = ["application/json"],
            method = [RequestMethod.GET])
    fun test( @PathVariable("testId") testId: String): ResponseEntity<String> {
        return ResponseEntity.ok(testId)
    }

Everything works

But when I use a generated interface:

@Validated
@RequestMapping("\${api.base-path:/v2/test}")
interface TestApi {
    @RequestMapping(
            value = ["/test/{testId}"],
            produces = ["application/json"],
            method = [RequestMethod.GET])
    fun test( @PathVariable("testId") testId: kotlin.String
): ResponseEntity<String> {
        return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
    }
}

and then override that method in the controller

override fun test( @PathVariable("testId") testId: String): ResponseEntity<String> {
        return ResponseEntity.ok(testId)
    }

I get a 404 return. So the RequestMapping annotations in the interface seems to be ignored

[Margarita Bobova]

@huehnerlady Thank you. I tried the same with java and get 404 too, so it seems like a Spring bug or restriction. Try to use @GetMapping in interface instead of a @RequestMapping like described in the article: https://www.baeldung.com/spring-interface-driven-controllers. It works.

[huehnerlady]

@Margarita Bobova could you maybe share a code snippet? For me a swap of RequestMapping to GetMa[pping does not resolve it 😞

[huehnerlady]

With Java it does work though … 🤔

[huehnerlady]

this is the generation of java:

@RequestMapping(value = "/test/{testId}",
            produces = { "application/json" },
            method = RequestMethod.GET)
    default ResponseEntity<String> test(@PathVariable("testId") String testId) {
        getRequest().ifPresent(request -> {
            for (MediaType mediaType: MediaType.parseMediaTypes(request.getHeader("Accept"))) {
                if (mediaType.isCompatibleWith(MediaType.valueOf("application/json"))) {
                    String exampleString = "null";
                    ApiUtil.setExampleResponse(request, "application/json", exampleString);
                    break;
                }
            }
        });
        return new ResponseEntity<>(HttpStatus.NOT_IMPLEMENTED);

    }

when I use it this way:

override fun test(testId: String?): ResponseEntity<String> {
        return ResponseEntity.ok(testId?: "")
    }

Then I get a 200

[Margarita Bobova]

@huehnerlady Here is a java project, changing to @GetMapping helps

demo 6.zip

[Margarita Bobova]

Really, for Kotlin changing to @GetMapping does not help. Will investigate

[huehnerlady]

I see, ok thank you. As said with a java interface it also wprks in kotlin with the @RequestMapping, it is just if the interface is also groovy 🙂

I strive to have a 100% kotlin service, and currently this problem is one of the obstacles I have to overcome 😞

[Margarita Bobova]

@huehnerlady the following code works for me:

import org.springframework.http.ResponseEntity
import org.springframework.stereotype.Controller

import org.springframework.web.bind.annotation.*

@Controller
class Controller : TestApi {

    override fun test(@PathVariable("testId") testId: String): ResponseEntity<String> {
        return ResponseEntity.ok(testId)
    }

}

Interface:

import org.springframework.http.HttpStatus
import org.springframework.http.ResponseEntity
import org.springframework.validation.annotation.Validated
import org.springframework.web.bind.annotation.PathVariable
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RequestMethod

@Validated
@RequestMapping("/api")
interface TestApi {
    @RequestMapping(
            value = ["/test/{testId}"],
            produces = ["application/json"],
            method = [RequestMethod.GET])
    fun test( @PathVariable("testId") testId: kotlin.String
    ): ResponseEntity<String> {
        return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
    }
}

Could you please try?

[huehnerlady]

hmm odd, for me I still get the 404 😞

I am using spring boot 2.2.6 and Spring 5.2.5. which version are you using?

[Margarita Bobova]

spring boot 2.3.1

[huehnerlady]

ok, will upgrade and have a look if that is the problem

[Margarita Bobova]

could you please share the project?

[huehnerlady]

unfortunately this is a closed project, so not easy to share. but if the spring upgrade does not work I will provide a sample project

[Margarita Bobova]

yes, sample project would be great! The problem reproduced for me before, but doesn’t reproduce now

[huehnerlady]

I tried to make a simple sample project but there it works. So I need to dive deeper into the code I guess, but for me it is very valuable to know, that it should work this way, so many many thanks for your help 🙂

[huehnerlady]

@Margarita Bobova I got it to work, it was a red hering as the kotlin-spring generator behaves differently from what they generate than the java-spring generator, that is why I had the problems. this is solved now.

The problem was, that the spring generator does not generate a requestMapping on Controller level, the kotlin-spring generator does. Therefore the endpoint was not available at the point I was expecting, but at a different path

Many many thanks 👍🏻

[Margarita Bobova]

Thank you :)