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javahibernate-validatorbean-validation

Empty validatedBy in @Constraint

I noticed that all built-in constraints have an empty value for the validatedBy parameter in @Constraint. i.e. @Constraint(validatedBy = {})

First, why are they allowed to have an empty value for validatedBy? I thought you can leave it blank only for constraint composition that does not need addtional validation?

Also, note that the Hibernate Validator can still find a validator implementation class for each built-in constraint, despite the validatedBy is empty, but if I leave the validatedBy blank for my constraint, my custom validator never gets picked up. Why is that?

Thanks.

Solution

  • Those built-in are treated in special implementation-specific way and their validators are configured programmatically.

    For Hibernate Validator it's done in ConstraintHelper.java. I think you can't achieve the same for your custom constraints.