Hibernate: org.hibernate.WrongClassException … instanceAlreadyLoaded

May 4th, 2009 by jeremychone

Hibernate inheritance and relationship could lead to the following exception:

Caused by: org.hibernate.WrongClassException: Object with id: 3 was not of the
specified subclass...
...
        at org.hibernate.loader.Loader.instanceAlreadyLoaded(Loader.java:1267)
        at org.hibernate.loader.Loader.getRow(Loader.java:1219)
        at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:603)
        at org.hibernate.loader.Loader.doQuery(Loader.java:724)
...

Putting @ForceDiscriminator near the @DiscriminatorValue(..) of your respective classes might solve the problem.
See Hibernate Annotation Doc

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