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Hibernate Validator 5.3.0.Alpha1 is out

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It’s my pleasure to announce the first release of Hibernate Validator 5.3!

The overarching idea for the 5.3 timeline is to prototype several features which may potentially be standardized in the Bean Validation 2.0 specification. For instance we’ll work on a solution for the long-standing request for sorting the constraints on single properties.

If you’d like to see any specific features addressed in that prototyping work (and eventually included in BV 2.0), then please get in touch and let us know which are the most important things you are missing from the spec. We’ve compiled a first list of issues we are considering for inclusion in BV 2.0. For sure we cannot address all of them, so it’ll greatly help if you tell us what would be most helpful to you.

Dynamic payloads for constraints

To get things rolling, the Alpha 1 allows to you to enrich custom constraint violations with additional context data. Code examining constraint violations can access and interpret this data in a safer way than by parsing string-based constraint violation messages. Think of it as a dynamic variant of the existing Bean Validation payload feature.

As an example, let’s assume we have a constraint @Matches for making sure a long property matches a given value with some tolerance:

public static class Package {

    @Matches(value=1000, tolerance=100)
    public long weight;
}

If the annotated value is invalid, the resulting constraint violation should have a specific severity, depending on whether the value lies within the given tolerance or not. That severity value could then for instance be used for formatting the error specifically in a UI.

The definition of the @Matches constraint is nothing new, it’s just a regular custom constraint annotation:

@Retention(RUNTIME)
@Constraint(validatedBy = { MatchesValidator.class })
@Documented
public @interface Matches {

    public enum Severity { WARN, ERROR; }

    String message() default "Must match {value} with a tolerance of {tolerance}";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};

    long value();
    long tolerance();
}

The constraint validator is where it’s getting interesting:

public class MatchesValidator implements ConstraintValidator<Matches, Long> {

    private long tolerance;
    private long value;

    @Override
    public void initialize(Matches constraintAnnotation) {
        this.value = constraintAnnotation.value();
        this.tolerance = constraintAnnotation.tolerance();
    }

    @Override
    public boolean isValid(Long value, ConstraintValidatorContext context) {
        if ( value == null ) {
            return true;
        }

        if ( this.value == value.longValue() ) {
            return true;
        }

        HibernateConstraintValidatorContext hibernateContext = context.unwrap(
                HibernateConstraintValidatorContext.class
        );
        hibernateContext.withDynamicPayload(
                Math.abs( this.value - value ) < tolerance ? Severity.WARN : Severity.ERROR
        );

        return false;
    }
}

In isValid() the severity object is set via HibernateConstraintValidatorContext#withDynamicPayload(). Note that the payload object must be serializable in case constraint violations are sent to remote clients, e.g. via RMI.

Validation clients may then access the dynamic payload like so:

HibernateConstraintViolation<?> violation = violations.iterator()
    .next()
    .unwrap( HibernateConstraintViolation.class );

if ( violation.getDynamicPayload( Severity.class ) == Severity.ERROR ) {
    // ...
}

What else is there?

Other features of the Alpha 1 releases are improved OSGi support (many thanks to Benson Margulies for this!), optional relaxation of parameter constraints (kudos to Chris Beckey!) and several bug fixes and improvements, amongst them support for cross-parameter constraints in the annotation processor (cheers to Nicola Ferraro!).

You can find the complete list of all addressed issues in the change log. To get the release with Maven, Gradle etc. use the GAV coordinates org.hibernate:{hibernate-validator|hibernate-validator-cdi|hibernate-validator-annotation-processor}:5.3.0.Alpha1. Alternatively, a distribution bundle containing all the bits is provided on on SourceForge (TAR.GZ, ZIP).

To get in touch, use the following channels:

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