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  1. HHH-5855

The method "merge" from the EntityManager causes a duplicated "insert" of a child entity.


    • Type: Bug
    • Status: Closed
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: 3.3.1, 3.6.0, 4.3.11, 5.0.2
    • Fix Version/s: 5.0.8
    • Environment:
      Hibernate-Core 3.6.0, Hibernate EntityManager 3.6.0, Derby, Spring 3.0.5 (Configuration), JUnit 4.5
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    • Last commented by a user?:


      The method "merge" from the EntityManager causes a duplicated "insert" of a child entity.
      Related to HHH-3332 Closed

      Observed Behavior:

      When you have an Entity A with a OneToMany(fetch=LAZY, cascade=ALL or (MERGE and PERSIST)) relationship to another Entity B and attempt to add an new B instance to A hibernate will generate a duplicate insert command upon commit.

      I have witnessed this problem occurring when this procedure is followed:

      1. retrieve an instance of A from persistence (A a = em.find(A.class, id))
      2. add a new B to A (a.getBs.add(new B()))
      3. merge instance 'a' back into persistence (em.merge(a))

      Upon transaction commit hibernate will generate an additional "insert" statement and insert the new instance of b into the data source twice.

      Expected behavior:

      I would expect hibernate to only perform a single insertion when 'a' is merged back to persistence and the B's are created through the cascade.

      Notes (Discoveries):

      This problem can be worked around by:

      • Changing the OneToMany relationship from a List to a Set
      • Only using either Cascade MERGE or PERSIST not both of ALL
      • Add a new B to A.getBs by adding to the '0' index (a.getBs.add(0,new B()))


        1. CascadeMergeTest.zip
          210 kB
        2. CascadeMergeTest.zip
          6 kB
        3. HHH-3332-again.zip
          19 kB
        4. HHH-5855.zip
          26 kB
        5. hhh-5855-master.zip
          12 kB
        6. hhh-5855-master-hibernate-5.0.2.zip
          12 kB
        7. hhh-5855-master-hibernate-5.0.4.zip
          12 kB
        8. hhh-5855-master-hibernate-5.0.5.zip
          12 kB

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