[bv-dev] Overriding constraints in inheritance hierarchies

[Emmanuel Bernard]

At one point the spec had an annotation akin to @IgnoreInheritedConstrains that applied on the target of the constraint

```
public class A { @Size(min = 1, max = 10) private String field1; @Min(2) private Integer field2; ... }

@ConstraintOverrides({
@ConstraintOverride(name="field1", constraint={@Size(min=4, max =20)}),
@ConstraintOverride(name="startDate", constraint={@Min(1)})
})
public class B extends A {
    @IgnoreInheritedConstrains @Size(min=4, max =20)
    String getField1() { ...  };

    @IgnoreInheritedConstrains @Min(1)
    Integer getField2() { ...  };
   

}
```

We removed it for a few reasons the main ones being that we could not find a good use case for it. It was mainly used to fix mistakes made in superclasses. I'm not against it but we need a use case.

Note that the field overriding must be done on the getter which is a bit weird in Java but makes sense in the "property" world of Bean Validation. If Java had proper properties or even overridable fields t would not be a problem. That's an irregularity of the Java language though.

I also like Matt's proposal a lot which is essentially captured in BVAL-229 but that's a nice to have feature. I'm afraid we will be short of time for this release.

Emmanuel

On 2 janv. 2012, at 22:43, Matt Benson wrote:

> One, albeit heavy-handed, way to approach this type of requirement
> isimplemented by the code
> athttp://svn.apache.org/viewvc/incubator/bval/sandbox/bval-jsr303-dynamic/.
>  This ValidationProvider provides a DynamicValidatorContext that canbe
> customized using its #constrain(Class, Annotation)
> and#constrain(Class, String, Annotation) methods.  The mechanism
> forhandling Annotation parameters is extensible, so one potential use
> ofthis functionality is the removal of existing constraints.  This
> mightprovide enough surface area to fuel a discussion on this type
> offunctionality for a future version of the spec.
> Matt
> On Mon, Jan 2, 2012 at 1:39 PM, Gunnar Morling
> <gunnar.morling at googlemail.com> wrote:
>> Hi experts,
>> 
>> just recently there was a ticket created in the HV tracker [1] which
>> suggests to provide a way for "overriding" constraints within
>> inheritance hierarchies, i.e. the constraints defined on a property of
>> a parent bean are re-defined on the same property on an inherited bean
>> type (instead of being added up).
>> 
>> The approach suggested in the ticket doesn't work as described there,
>> as it isn't possible to define a generic array of constraint
>> annotations. Nevertheless it might be useful to have a means of
>> disabling the constraints from super types in special cases.
>> 
>> That said, I personally didn't have that requirement yet, but it makes
>> sense to me that someone might find this useful.
>> 
>> Any thoughts?
>> 
>> --Gunnar
>> 
>> 
>> [1] https://hibernate.onjira.com/browse/HV-548
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