Hi, anybody know why using @Validated on a Controller class in Spring could mess up with constructor...

# server

[Andrzej Sawoniewicz]

Hi, anybody know why using @Validated on a Controller class in Spring could mess up with constructor injections? I simply get null values for all injected objects. The problem came out after migration to Kotlin from Java.

[Mikhail]

Code?

[Mikhail]

I use @Validated on an interface. I prefer interface-driven controllers

[Andrzej Sawoniewicz]

It works:
@RestController
@Validated
public class TestController {
private NativeWebRequest request;

@Autowired
public TestController(NativeWebRequest request) {
this.request = request;
}

@GetMapping(
value = "/test/{countryCode}",
produces = {"application/json"})
public ResponseEntity<String> getTestResponse(@Pattern(regexp = "^[A-Z]{2}$") String countryCode) {
return new ResponseEntity<>("ok", HttpStatus.OK);
}
}


It does not work:
@RestController
@Validated
open class TestController2 @Autowired constructor(private val request: NativeWebRequest) {
@GetMapping(value = ["/test2/{countryCode}"], produces = ["application/json"])
fun getTest2Response(countryCode: @Pattern(regexp = "^[A-Z]{2}$") String?): ResponseEntity<String> {
return ResponseEntity("ok", HttpStatus.OK)
}
}


It works:
@RestController
//@Validated
open class TestController2 @Autowired constructor(private val request: NativeWebRequest) {
@GetMapping(value = ["/test2/{countryCode}"], produces = ["application/json"])
fun getTest2Response(countryCode: @Pattern(regexp = "^[A-Z]{2}$") String?): ResponseEntity<String> {
return ResponseEntity("ok", HttpStatus.OK)
}
}

[Mikhail]

well, everything works fine for me
note that ConstraintViolationException is not handled in the first request

[Mikhail]

Also, you probably should inject NativeWebRequest not as a constructor parameter, but define it as a parameter of a function that handles the request
look at my snippet

[Andrzej Sawoniewicz]

THanks, any idea why it could not work on my side? @RestController
@Validated
open class TestController2 @Autowired constructor(private val thing: Thing) {
@GetMapping(value = ["/test2/{countryCode}"])
fun getTest2Response(countryCode: @Pattern(regexp = "^[A-Z]{2}$") String?): ResponseEntity<String> {
return ResponseEntity(thing.value, HttpStatus.OK)
}
}

[Andrzej Sawoniewicz]

I still get null value for the injected thing object

[Andrzej Sawoniewicz]

I use springboot 2.6.7 and Kotlin 1.6.21

[Mikhail]

I see you use open do you use spring support plugin for kotlin?

[Mikhail]

in the plugins {} block of your build.gradle.kts :

kotlin("plugin.spring") version "1.6.21"

[Andrzej Sawoniewicz]

Yes but for groovy version gradle: id 'org.jetbrains.kotlin.jvm' version '1.6.21'

[Mikhail]

removed the spring plugin from my build config:

[Mikhail]

do you actually have that plugin?
https://plugins.gradle.org/plugin/org.jetbrains.kotlin.plugin.spring

[Andrzej Sawoniewicz]

plugins {
id 'org.springframework.boot' version '2.6.7'
id 'io.spring.dependency-management' version '1.0.11.RELEASE'
id 'java'
id 'org.jetbrains.kotlin.jvm' version '1.6.21'
}

[Mikhail]

well, repalce it with:

plugins {
    id 'org.springframework.boot' version '2.6.7'
    id 'io.spring.dependency-management' version '1.0.11.RELEASE'
    id 'java'
    id 'org.jetbrains.kotlin.jvm' version '1.6.21'
    id "org.jetbrains.kotlin.plugin.spring" version '1.6.21'
}

[Andrzej Sawoniewicz]

Wow, it works! I missed that 🙂 Thank you very much!

[Diego Marzo]

Hi @Andrzej Sawoniewicz, cool you issue is fixed!

I believe you could define your controller like this also:

@Validated
@RestController
class TestController(private val request: NativeWebRequest)

If you have your spring plug there is no need of "open", no need for "@Autowired" and no need for the explicit "constructor"

I know it is not super important but you can remove some boilerplate