[FIXED] Custom class validator throws all errors even if only one field is not valid

Issue

In Java Spring boot i made class custome validator. And if even one field fail in Validator i get always both error messages

[ "WRONG_CAR_COLOR", "WRONG_YEAR_OF_PRODUCTION" ]

public class ElectricCarSpecValidator implements ConstraintValidator<ElectricCarSpec, CreateCarCommand> {

private static final Integer minYearOfProduction = 2000;
private static final Integer carColorRed = 10;
private static final Integer electricCarId = 5;

@Override
public boolean isValid(CreateCarCommand command, ConstraintValidatorContext context) {
    if (!command.getFuelTypeId().equals(electricCarId)) {
        return true;
    }
    return command.getYearOfProduction() >= minYearOfProduction && !command.getCarColorId().equals(carColorRed);
}

Validator:

    @ExceptionHandler(MethodArgumentNotValidException.class)
public ResponseEntity handleMethodArgumentNotValid(MethodArgumentNotValidException ex) {
    List<String> errors = ex.getAllErrors().stream()
            .map(DefaultMessageSourceResolvable::getDefaultMessage)
            .collect(Collectors.toList());
    return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(errors);
}

Adnotation:

@ElectricCarSpec.List({
    @ElectricCarSpec(field = "yearOfProduction", message = "WRONG_YEAR_OF_PRODUCTION"),
    @ElectricCarSpec(field = "carColorId", message = "WRONG_CAR_COLOR")

})

Solution

The problem is that whatever field you specify, you always do the very same validation - checking if both fields are valid.

return command.getYearOfProduction() >= minYearOfProduction 
     && !command.getCarColorId().equals(carColorRed);

In order to take your field property into account, you would need to override initialize(A constraintAnnotation). It's guaranteed by the docs to be called before isValid.

Initializes the validator in preparation for isValid(Object, ConstraintValidatorContext) calls. The constraint annotation for a given constraint declaration is passed. This method is guaranteed to be called before any use of this instance for validation.

Something like this:

public class TestConstraintValidator implements ConstraintValidator<ElectricCarSpec, CreateCarCommand> {

    private String field;

    @Override
    public void initialize(ElectricCarSpec constraintAnnotation) {
        this.field = constraintAnnotation.field();
    }

    @Override
    public boolean isValid(CreateCarCommand value, ConstraintValidatorContext context) {
        if (field.equals("yearOfProduction")) {
            //validate year of production
        }
        if (field.equals("carColorId")) {
            //validate color id
        }
        return true;
    }
}

Having few ifs for every field you want to validate is fine, but if there are too many fields to check, you may consider writing a strategy pattern to pick correct validation strategy depending on field name.

Answered By - Chaosfire
Answer Checked By - Candace Johnson (JavaFixing Volunteer)