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Hibernate: Confusion with Multiple Objects of Same Identity
Issue:
When attempting to save or update an object using Hibernate's saveOrUpdate method, an exception is thrown:
org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session
Context:
The issue arises when an object, such as a RoleBean, is assigned to multiple entities, such as a UserBean and a GroupBean, within the same transaction. This can occur when the object has a many-to-many relationship.
For instance, in the given scenario, RoleBean#1 is initially assigned to GroupBean#1. When attempting to add it to UserBean#1 within the same session, the exception is encountered.
Resolution:
The cause of the exception is the existence of two different instances of the RoleBean object within the session. One instance is directly associated with the UserBean, while the other is indirectly associated through the GroupBean.
To resolve this issue, consider the following options:
By implementing one of these approaches, you can resolve the exception and ensure that objects with the same identity are properly handled within a single Hibernate session.
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