Details
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Type:
Bug
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Status: Open
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Priority:
Critical
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Resolution: Unresolved
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Affects Version/s: 3.3.1, 3.6.0
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Fix Version/s: None
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Component/s: annotations, core, entity-manager
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Labels:None
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Environment:Hibernate-Core 3.6.0, Hibernate EntityManager 3.6.0, Derby, Spring 3.0.5 (Configuration), JUnit 4.5
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Bug Testcase Reminder (view):
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Last commented by a user?:true
Description
The method "merge" from the EntityManager causes a duplicated "insert" of a child entity.
Related to HHH-3332
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:
- retrieve an instance of A from persistence (A a = em.find(A.class, id))
- add a new B to A (a.getBs.add(new B()))
- 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()))
Activity
Check my HHH-3332-again.zip attachement to see it still replicates on 4.x version too.
Or:
Starting at line 75:
//assertEquals(2, parent.getChildren().size());
if (parent.getChildren().size() == 4)
Mihalcea Vlad
added a comment - Check my HHH-3332 -again.zip attachement to see it still replicates on 4.x version too.
Or:
https://github.com/vladmihalcea/vladmihalcea.wordpress.com/blob/master/hibernate-facts/src/test/java/com/vladmihalcea/HibernateBagDuplicateTest.java
Starting at line 75:
//assertEquals(2, parent.getChildren().size());
if (parent.getChildren().size() == 4)
{
LOG.error("Duplicates rows generated!");
}
@Mihalcea Thank you for uploading the test case for hibernate 4.
Seth Martin
added a comment - @Mihalcea Thank you for uploading the test case for hibernate 4. Also, if the bug is still present in version 4 my test cases should still fail. i will dbl check them when i have some extra time.
Seth Martin
added a comment - Also, if the bug is still present in version 4 my test cases should still fail. i will dbl check them when i have some extra time. For the past 5 years this was my workaround:
http://vladmihalcea.com/2013/10/16/hibernate-facts-favoring-sets-vs-bags/
Mihalcea Vlad
added a comment - For the past 5 years this was my workaround:
http://vladmihalcea.com/2013/10/16/hibernate-facts-favoring-sets-vs-bags/ Confirmed on Version 4.3.4.Final using HHH-3332 Again code attached
Rowland Mynhardt
added a comment - Confirmed on Version 4.3.4.Final using HHH-3332 Again code attached 
Because A is the owner of the relationship, you need to also call:
b.setA( a );
I believe you will still have problems though because of
HHH-5732.Please let us know.
Thanks,
Gail