As per post entitled "Unexpected 'detached entity passed to persist' error" in the "Hibernate Annotations, EntityManager, Search, Validator, Shards" forum, original posting by darrenclarke.

I have a Person entity that has a 1:1 with an Address entity. Both have int PKs. Person has an additional unique column (accountNumber).

When I persist() a new Person that has an accountNumber that causes a unique-constraint violation (deliberately for testing purposes), catch the resulting exception and perform a rollback(), the database state is correct, but the application's internal entity state is incorrect (person.getId()==0, but person.getAddress().getId() is not 0, i.e. the PK value has not been rolled back).

Emmanuel suggested using hibernate.use_identifier_rollback=true, but that has made no difference.

The attached files replicate the problem (note I haven't performed proper ThreadLocal-based EntityManager creation and the like, it's just a bare-bones standalone example to replicate the problem).


Running Main and then stepping through the stdout reveals the following:
   [stdout] Creating person 1 ...
   [stdout] Persisting person 1 ...
   [stdout] Prior to merge/persist, person.getId()=0, person.getAddress().getId()=0
   [stdout] merge/persist succeeded.
   [stdout] Creating person 2 (accountNumber is the same as person 1's) ...
   [stdout] Persisting person 2 ...
   [stdout] Prior to merge/persist, person.getId()=0, person.getAddress().getId()=0
   [stdout] Prior to rollback, person.getId()=0, person.getAddress().getId()=2
   [stdout] After rollback, person.getId()=0, person.getAddress().getId()=2
   [stdout] Creation of new person failed due to duplicate account number (1) - retrying with different account number (2, retry# 1) ...
   [stdout] Prior to merge/persist, person.getId()=0, person.getAddress().getId()=2
   [stdout] Prior to rollback, person.getId()=0, person.getAddress().getId()=2
   [stdout] After rollback, person.getId()=0, person.getAddress().getId()=2
   [stdout] Exception whilst persisting person 2:
java.lang.Exception: Unable to save person
[snip]
Caused by: javax.persistence.PersistenceException: org.hibernate.PersistentObjectException: detached entity passed to persist: testapp.domain.Address
[snip]

I.e. the first persist is fine. The second persist (with unique-constraint violation) fails, but the address ID isn't reset after the rollback. Therefore when the second persist is retried with a valid accountNumber, the persist fails again as it believes an existing but detached address is referenced.