How do I customize default error message from spring @Valid validation?

Question

DTO:

public class User {

    @NotNull
    private String name;

    @NotNull
    private String password;

    //..
}

Controller:

Answer 1

One way to do it is adding message in @NotNull annotation on entity properties. And adding @Valid annotation in controller request body.

DTO:

public class User {
   
    @NotNull(message = "User name cannot be empty")
    private String name;

    @NotNull(message = "Password cannot be empty")
    private String password;

    //..
}

Controller:

@RequestMapping(value = "/user", method = RequestMethod.POST)
public ResponseEntity saveUser(@Valid @RequestBody User user) {
    //..
    return new ResponseEntity<>(HttpStatus.OK);
}
// Add one 
@ExceptionHandler(MethodArgumentNotValidException.class)
public ResponseEntity> handleException(MethodArgumentNotValidException ex) {
// Loop through FieldErrors in ex.getBindingResult();
// return *YourErrorReponse* filled using *fieldErrors*
}