java.lang.UnsupportedOperationException: Attempted to serialize java.lang.Class: org.hibernate.proxy.HibernateProxy

Question

I'm using a Restful web service (Jersy implementation) with a JSF application and used Json to get the data as follows:

    carObjectDao = new GenericDAO<carObject>(carObject.class);
    List<carObject> allCars = carObjectDao.readAll();
    Gson gson = new Gson();
    String carString = gson.toJson(allCars);
    System.err.println(carString );
    return carString ;

i run the application in debug mode and allCars is filled with the data correctly, but after that an exception is thrown :

java.lang.UnsupportedOperationException: Attempted to serialize java.lang.Class: org.hibernate.proxy.HibernateProxy. Forgot to register a type adapter?

i don't know the root cause of the exception

You have to unproxy the HibernateProxy objects, or if you dont really need the data, just set em as null. — Ziul, May 15 '13 at 22:33

score 6 · Answer 1 · edited May 23 '17 at 12:25

6

This is a known problem: Could not serialize object cause of HibernateProxy

JSon can't deserialize HibernateProxy objects, so you either unproxy or remove em.

Or, you can eager fetch the lazy data.

edited May 23 '17 at 12:25

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answered May 15 '13 at 22:39

Ziul

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How to Unproxy or remove them, i read that post but didn't understand – Eslam Hamdy May 15 '13 at 23:01
Fist you have to undestand how the lazy initialization works, when you dont eager fetch a collection, or load an object, it comes as a Hibernate proxy collection/object, you have to find out from your allCars objects, which child collection/objects are coming as HibernateProxy instead of real data. – Ziul May 15 '13 at 23:28
After that, you can decide what to do with em (remove em or fix em). – Ziul May 15 '13 at 23:30

score 0 · Answer 2 · answered Oct 15 '20 at 07:39

Try parsing through ObjectMapper as

    carObjectDao = new GenericDAO<carObject>(carObject.class);
    List<carObject> allCars = carObjectDao.readAll();
    String carString = new ObjectMapper().writeValueAsString(allCars);
    System.err.println(carString );
    return carString ;

java.lang.UnsupportedOperationException: Attempted to serialize java.lang.Class: org.hibernate.proxy.HibernateProxy

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