anyone could tell me what’s wrong with this `existingUser.copy(username...` here : ```package com.ex...

# spring

[dany giguere]

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

[Klitos Kyriacou]

Are you sure com.example.app.models.User has a copy method? Data classes have a compiler-generated copy method, but maybe User is not a data class.

[dany giguere]

Thanks for the help @Klitos Kyriacou I ended up changing my class to data class User ( which add the copy method.

[dany giguere]

https://kotlinlang.org/docs/data-classes.html