Validate properties of a superclass

mstewie · **Joined:** Tue Jul 05, 2011 7:28 am **Posts:** 10

Hi all,

I have an entity class that inherits from a base class that contains properties such as Id, CreateDate, etc. I cannot modify this base class so my question is: How can I place validation constraints on these properties from my sub class? e.g. the CreateDate cannot be in the past. I know I could create a custom constraint that I place at class level on my sub class or I could configure it through XML but I was wondering if there is any other ways of placing validation constraints on properties of superclasses from your sub class. I am using Hibernate Validator 4.2.0.Final.

Thanks,
M

hardy.ferentschik · **Posted:** Mon Aug 22, 2011 9:09 am

Hi,

using the Bean Validation API only you have to use XML. Using Hibernate Validator you could also use the programmatic constraint API. But in one of the cases you are placing the constraints on the subclass.

--Hardy

mstewie · **Joined:** Tue Jul 05, 2011 7:28 am **Posts:** 10

Thanks Hardy for the reply.

I don't know if I'm taking the correct approach but I was thinking of implementing something like the following:

@ConstraintOverride(name="createDate", constraints = {@NotNull, @...})
public class MyEntity extends BaseEntity {
...
}

My entity classes are currently using constraint annotations so I'd like to continue to use that pattern rather than having some constraints in an XML file and some as annotations. Also I know I could create a custom constraint to validate the createDate property and place it on the MyEntity class but I'd like something a bit more generic that I could basically apply my constraints to any property of a superclass without having to modify the superclass.

I'd appreciate your input on the direction I am taking or am I over complicating the solution?

Thanks,
Mark

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

Hi,

that's an interesting idea, I'm afraid though that it's not really possible to implement this in the generic way you'd like to.

The problem is the "constraints" member of your @ConstraintOverride annotation which you can't define it in a generic way (it's not possible to have an array of java.lang.annotation.Annotation as annotation member). So you would have to specify the constraints in a textual way which would be very error-prone.

But even if this were possible I think there are some questions. In case there are several sub-types of BaseEntity, would the @NotNull constraint for createDate be defined on every of these sub-types or only one? The first would be very redundant, the second probably quickly becoming complex (how to determine all constraints applying to BaseEntity?).

All in all I think using the XML descriptor or the programmatic API is the approach you likely should take.

Hth,

--Gunnar

hardy.ferentschik · **Posted:** Tue Aug 23, 2011 5:45 am

Hi,

I don't really have much to add, except I think Gunnar already gave you the best advice :-)

mstewie · **Joined:** Tue Jul 05, 2011 7:28 am **Posts:** 10

Thanks Gunnar and Hardy for your input.

Just one last question - when you say "the programmatic API approach", I presume you mean creating a custom constraint validator for the property in the superclass that I want to validate?

e.g.

@ValidCreateDate
public class MyEntity extends BaseEntity {
...
}

Thanks again,
Mark

hardy.ferentschik · **Posted:** Tue Aug 23, 2011 11:01 am

What me mean is the Hibernate Validator specific programmatic constraint definition API - http://docs.jboss.org/hibernate/stable/ ... ammaticapi

pediddle · **Joined:** Sun Feb 27, 2011 11:40 am **Posts:** 8

Haven't seen this option mentioned yet -- couldn't you place the annotations on overridden getters?

Code:

class MyEntity extends BaseEntity {
    @NotNull
    @...
    @Override
    public Date getCreateDate() {
        return super.getCreateDate();
    }
}