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I'am currently working on a Jersey project and decided to use Hibernate validator for the parameter validations. All dependencies injected on the Endpoint classes are properly initialized. However for those dependencies in the ConstraintValidator classes, it always throw a NPE. So i followed the guide on Spring+hibernate guide and registered

bean id="validator" class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean"

and used the @Autowired annotation for the services in the ConstraintValidator class which needs to be injected.

are there side effects of using it? Is there a way to avoid the autowiring annotation in ConstraintValidator class and still injecting the values? I tried manually registering the constraintValidator class in the context as bean, adding a property reference to the service that i need, however it throws a null pointer exception.

Slava Semushin
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geneqew
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1 Answers1

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"Hibernate Validator - JSR 303 Reference Implementation - Reference Guide" says something about portality:

Warning

Any constraint implementation relying on ConstraintValidatorFactory behaviors specific to an implementation (dependency injection, no no-arg constructor and so on) are not considered portable.

So, is it a bad thing? In my opinion it's not. Of course you are now coupled to the DI container (Spring) and can't easily reuse validators (e.g. when not using Spring). On the other hand, with your validators build by a Spring factory you can take full advantage of the framework and do very heavy lifting (read revision data for entities and comparison of previous states, call arbitrary services, enhance or localize validation messages, ...).

One thing you must be very careful about is that a validator's semantics is normally read-only and should not cause side-effects by calling it. For example don't accidentally flush data to the database because of some auto-flushing by invoking a (transactional) service or reading data inside your validator.

jeha
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  • with hibernate validator 6 you can implement your own `ConstraintValidatorFactory` to deal with non-empty constructors, but thanks anyway for pointing me in the right direction :) – ThanksForAllTheFish Jan 18 '19 at 08:08