Cross field validation with Hibernate Validator (J

Question

Is there an implementation of (or third-party implementation for) cross field validation in Hibernate Validator 4.x? If not, what is the cleanest way to implement a cross field validator?

As an example, how can you use the API to validate two bean properties are equal (such as validating a password field matches the password verify field).

In annotations, I'd expect something like:

public class MyBean {
  @Size(min=6, max=50)
  private String pass;

  @Equals(property="pass")
  private String passVerify;
}

Answer 1

If you’re using the Spring Framework then you can use the Spring Expression Language (SpEL) for that. I’ve wrote a small library that provides JSR-303 validator based on SpEL – it makes cross-field validations a breeze! Take a look at https://github.com/jirutka/validator-spring.

This will validate length and equality of the password fields.

@SpELAssert(value = "pass.equals(passVerify)",
            message = "{validator.passwords_not_same}")
public class MyBean {

    @Size(min = 6, max = 50)
    private String pass;

    private String passVerify;
}

You can also easily modify this to validate the password fields only when not both empty.

@SpELAssert(value = "pass.equals(passVerify)",
            applyIf = "pass || passVerify",
            message = "{validator.passwords_not_same}")
public class MyBean {

    @Size(min = 6, max = 50)
    private String pass;

    private String passVerify;
}

Answer 2

Solution realated with question: How to access a field which is described in annotation property

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Match {

    String field();

    String message() default "";
}

---

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = MatchValidator.class)
@Documented
public @interface EnableMatchConstraint {

    String message() default "Fields must match!";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};
}

---

public class MatchValidator implements  ConstraintValidator<EnableMatchConstraint, Object> {

    @Override
    public void initialize(final EnableMatchConstraint constraint) {}

    @Override
    public boolean isValid(final Object o, final ConstraintValidatorContext context) {
        boolean result = true;
        try {
            String mainField, secondField, message;
            Object firstObj, secondObj;

            final Class<?> clazz = o.getClass();
            final Field[] fields = clazz.getDeclaredFields();

            for (Field field : fields) {
                if (field.isAnnotationPresent(Match.class)) {
                    mainField = field.getName();
                    secondField = field.getAnnotation(Match.class).field();
                    message = field.getAnnotation(Match.class).message();

                    if (message == null || "".equals(message))
                        message = "Fields " + mainField + " and " + secondField + " must match!";

                    firstObj = BeanUtils.getProperty(o, mainField);
                    secondObj = BeanUtils.getProperty(o, secondField);

                    result = firstObj == null && secondObj == null || firstObj != null && firstObj.equals(secondObj);
                    if (!result) {
                        context.disableDefaultConstraintViolation();
                        context.buildConstraintViolationWithTemplate(message).addPropertyNode(mainField).addConstraintViolation();
                        break;
                    }
                }
            }
        } catch (final Exception e) {
            // ignore
            //e.printStackTrace();
        }
        return result;
    }
}

And how to use it...? Like this:

@Entity
@EnableMatchConstraint
public class User {

    @NotBlank
    private String password;

    @Match(field = "password")
    private String passwordConfirmation;
}

Answer 3

You need to call it explicitly. In the example above, bradhouse has given you all the steps to write a custom constraint.

Add this code in your caller class.

ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
validator = factory.getValidator();

Set<ConstraintViolation<yourObjectClass>> constraintViolations = validator.validate(yourObject);

in the above case it would be

Set<ConstraintViolation<AccountCreateForm>> constraintViolations = validator.validate(objAccountCreateForm);