Hibernate Validator: Attribute Overriding

oprobst · **Joined:** Wed Jul 10, 2013 1:12 pm **Posts:** 2

Hi

I am currently working on my master thesis using Hibernate Validator and it is really great. While working with the library, I came up with the following question:

I have the following constraint which is a constraint composition:

Code:

@ConstraintComposition(CompositionType.OR)
@Deadline
@Min(value = 0)
@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER })
@Retention(RUNTIME)
@Documented
@Constraint(validatedBy = { })
@ReportAsSingleViolation
public @interface MinOnDeadline {
    
    Class<? extends Payload>[] payload() default {};
    
    String message() default "the deadline has expired.";

    Class<?>[] groups() default {};
    
    @OverridesAttribute(constraint=Min.class, name="value")
    long value();
    
}

Why do I have to specify a value for the @Min(value = 0) annotation?

Thank you very much.
Oliver

Gunnar · **Joined:** Sat Jan 24, 2009 12:46 pm **Posts:** 388

Hi Oliver,

The attribute has no default value, meaning it must be specified when using @Min. Otherwise the code won't compile. This is to prevent using the constraint in a wrong way by "forgetting" to set a value.

In the case of composition where the attribute is overridden this is a little bit uncomfortable, but the advantages of ensuring proper usage in the vast majority of use cases outweigh this. Which value you specify here doesn't matter as it is overridden anyways.

--Gunnar