Building Dynamic ConstraintViolation Error Messages

Question

I\'ve written a validation annotation implemented by a custom ConstraintValidator. I also want to generate very specific ConstraintViolation objects th

Answer 1

That's not possible with the standardized Bean Valiation API, but there is a way in Hibernate Validator, the BV reference implementation.

You need to unwrap the ConstraintValidatorContext into a HibernateConstraintValidatorContext which gives you access to the addExpressionVariable() method:

public class MyFutureValidator implements ConstraintValidator {

    public void initialize(Future constraintAnnotation) {}

    public boolean isValid(Date value, ConstraintValidatorContext context) {
        Date now = GregorianCalendar.getInstance().getTime();

        if ( value.before( now ) ) {
            HibernateConstraintValidatorContext hibernateContext =
                context.unwrap( HibernateConstraintValidatorContext.class );

            hibernateContext.disableDefaultConstraintViolation();
            hibernateContext.addExpressionVariable( "now", now )
                .buildConstraintViolationWithTemplate( "Must be after ${now}" )
                .addConstraintViolation();

            return false;
        }

        return true;
    }
}

The reference guide has some more details.