Hello Mauro,
I mistyped when I wrote cascade remove - I meant to write cascade
merge or cascade persist. Any references to 'first' could be
causing it to be resurrected, not just ones from the 'second'
instance's object graph. I also noticed you are using cascade
refresh and lazy relationships - refresh of the referenced entity
over a lazy reference will be delayed until it is accessed,
potentially wiping out changes made so far. Something that causes a
refresh of firstCollection for instance might get triggered after
the remove call but before the flush, and cause firstCollection to
still reference first and cause its resurrection in the persistence
unit. I would detail all the references in your object model to the
'first' class and check that one isn't interfering.
If you haven't already, I'd recommend turning on EclipseLink logging
and matching statements up to the calls in your code causing them,
and trying to determine what is different when the issue occurs vs
when it doesn't. You might also try delaying or removing the
constraint, so that you can see if EclipseLink eventually issues the
delete so we can see if it is just an ordering issue or if it never
does, and so is a resurrection issue in the application references
as mentioned before.
Best of luck,
Chris
You should turn on logging to see the statements executed in
relation to your calls, and possibly relax the
On 02/03/2016 4:06 AM, Mauro Molinari
wrote:
Hi Chris,
thank you for your help.
Actually, all the mentioned code is executed within the same
transactional method body. No data change is performed before.
firstCollection is obtained directly from first.getFirstCollection().
Between this call and the removal of first there are only other
getters calls (which return other related entities that are not
modified):
first.getFoo()
firstCollection.getBar()
first.getSomethingElse()
Then, after the deletion of second, and before the
query, there's nothing.
The First entity is certainly not referenced by Second,
nor by any remove-cascaded entity related to Second
(it was an explicit design choice).
In the actual code I'm using Spring Data JPA to perform
deletions and queries, but I don't think it should matter.
What I may try to do is to clear the reference between first and
second before applying deletions, something like:
Second second = first.getSecond();
first.setSecond(null);
entityManager.remove(first);
entityManager.remove(second);
but it's a shot in the dark. Also, I'm not sure what the "lesson
learnt" should be, in order to avoid this problem in the
future...
Thanks again,
Mauro
Il 01/03/2016 19:48, christopher delahunt ha scritto:
Hello Mauro,
Is there anything else that might reference the first instance?
Could the firstCollection.getFirsts().remove(first)
This sometimes happens if you have something left in your object
model still referencing the first instance with a relationship
marked cascade remove or cascade persist, causing the traversal
of the object model to 'undo' the remove call. This may be
inconsistent due to lazily fetched relationships, and how the
traversal of the model discovers unmanaged instances.
Best Regards,
Chris
On 01/03/2016 12:08 PM, Mauro
Molinari wrote:
Hello,
I have the following problem that puzzles me.
I have an entity, let's call it First, which references
another entity, let's call it Second.
The relationship is this:
@Entity
public class First {
// ...
@OneToOne(
cascade = { CascadeType.DETACH,
CascadeType.PERSIST,
CascadeType.REFRESH },
fetch = FetchType.LAZY,
optional = false,
orphanRemoval = false)
private Second second;
}
The relationship is unidirectional, i.e. there's no @OneToOne
relationship mapped in Second towards First.
First also has a @ManyToOne relationship towards a
FirstCollection entity. I don't think it should matter at all,
but I say it for completeness.
Then I have some code that takes a First instance (let's call
it "first") and does some things like:
FirstCollection firstCollection =
first.getFirstCollection();
// do some read-only operations on first
// remove first from the FirstCollection related
entities
firstCollection.getFirsts().remove(first);
// delete first
entityManager.remove(first);
// delete the related second instance
entityManager.remove(first.getSecond());
// perform a read query on an entity related to
first
When the last step is executed, a flush before the execution
of the read query is performed; I see something like this in
the stack trace:
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.flush(EntityManagerImpl.java:879)
at org.eclipse.persistence.internal.jpa.QueryImpl.performPreQueryFlush(QueryImpl.java:967)
at org.eclipse.persistence.internal.jpa.QueryImpl.executeReadQuery(QueryImpl.java:207)
The problem is that this lfush seems to perform the deletion
of second (together with some of its cascaded deleted
entities) BEFORE the deletion of First. I mean, the log shows
a call to DELETE on the Second table, but no previous delete
on the First table. This causes a foreign key constraint
failure.
This seems to happen only sometimes. My question is:
- how is it possible? I'm calling remove on First before
calling remove on Second!
- how to avoid this problem?
Thanks in advance,
Mauro
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