Class cast exception on hibernate5 module

[tomaldguz]

I am getting this exeption when trying to serialize a a collection of objects with lazy collections as atributes:

com.fasterxml.jackson.databind.JsonMappingException: org.hibernate.internal.SessionImpl cannot be cast to javax.persistence.EntityManager (through reference chain: java.util.ArrayList[0]->com.checkout.model.Category["items"])

The problem is reproducible since 2.8.6 forward, using 2.8.5 I dont have this problem. I am working with spring and hibernate

I am initializing this way:

public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() { MappingJackson2HttpMessageConverter jsonConverter = new MappingJackson2HttpMessageConverter(); ObjectMapper objectMapper = new ObjectMapper(); objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false); objectMapper.configure(MapperFeature.DEFAULT_VIEW_INCLUSION, true); Hibernate5Module hibernateModule = new Hibernate5Module(sessionFactory().getObject()); hibernateModule.enable(Hibernate5Module.Feature.FORCE_LAZY_LOADING); objectMapper.registerModule(hibernateModule); jsonConverter.setObjectMapper(objectMapper); return jsonConverter; }

[cowtowncoder]

Unfortunately Hibernate project has made a few incompatible changes to classes this module needs, so this may depend on version of Hibernate you are using.
So, which Hibernate version are you using?

[tomaldguz]

I am using Hibernate 5.0.12, tried with 5.1.10 but had the same result.

[cowtowncoder]

@tomaldguz Ok that's odd then. I thought it was 5.2 that was problematic. But maybe a PR to fix things for 5.2 broke 5.0/5.1 instead?

For Jackson 3.x I think we will deprecate this module since no one maintains it; it has been nothing but source of problems.

[tomaldguz]

That would be a shame, I think it is a useful module, I will try to see if it works with 5.2.

[cowtowncoder]

@tomaldguz Agreed. Would definitely like to see new contributors, any help is appreciated. Some of earlier work visible via PRs, may make sense to at-mention people who have worked.

[cowtowncoder]

Ok. So... fundamentally there is a big 5.1->5.2 problem with TransactionManager being moved to a different Java package. Reasons this may be a big problem is that it then changed signature of any method that has manager as return or argument type. Worst, it may not be a problem with compilation (i.e. to some degree may be source compatible -- depending on imports).

I made some changes to try to alleviate this, and tried running existing test suite (extra 5-2 compat).
Tests did not fail on ClassNotFoundError; and all standard tests passed for all 5.0 - 5.3 Hibernate versions.
But 5.2 test suite only passes on 5.2, 5.3, despite compiling on 5.1 and 5.0. I am not 100% sure if this is or is not a problem, but my gut feeling is that version 2.9.7 is much more likely to work with Hibernate 5.2.x and 5.3.x libraries. And there may be lurking issues for 5.0.x / 5.1.x.

Oh joy.