Matt Watson created CAY-2792:
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Summary: Fix Insertion Order For Reflexive DataObjects
Key: CAY-2792
URL: https://issues.apache.org/jira/browse/CAY-2792
Project: Cayenne
Issue Type: Bug
Components: Core Library
Affects Versions: 4.2.RC1, 4.2.RC2
Environment: Java 17
Reporter: Matt Watson
For terminology's sake, I assume _Reflexive_ refers to when you have 2 objects
of the same Model, that are related, in this case, parent/child
(ToOne/HasMany). If this assumption is incorrect we can rename the title.
For a little history on this, we never encountered this bug until we upgraded
to {{4.2.RC1}}, and I recently tested on {{4.2.RC2}} and the bug still exists.
For a while I thought this was only a bug in our environment, thinking that our
code was causing the issue because Cayenne has a passing test in
{{CayenneDataObjectRelationshipsIT.testReflexiveRelationshipInsertOrder1}}. But
as I got to digging, the error occurs when the parent also has a relationship
to some "Other" object that is not of the same model.
My commit has a breaking test. I have not worked on a fix yet, but will begin
investigating. I suspect it has to do with the work done in CAY-2571, but I am
not certain yet.
The issue is that Cayenne randomly tries to commit the child record in front of
the parent record, therefore the database throws a Foreign Key error, since the
parent does not yet exist when the child is inserted. Because of this
randomness, my breaking test attempts this process 100 times. You will also see
another test that passes with the same Models but without setting the "ToOne"
Other object.
here is a look at the code that "randomly" fails:
{code:java}
public void addReflexiveParentAndChildWithOtherRelationshipOnParent() {
// can add Reflexive Parent (that belongsTo Other) and Child,
// we will do this 100 times, because it randomly does it
correctly/incorrectly
// given some "other" Object
final Other other = context.newObject(Other.class);
other.setName("OtherB");
context.commitChanges();
final int attempts = 100;
int errors = 0;
for (int i = 0; i < attempts; i++) {
// when parent is created and associated to "Other"
final Reflexive parent = context.newObject(Reflexive.class);
parent.setName("parentB"+i);
parent.setToOther(other);
// and child is created and associated to "Parent"
final Reflexive child = context.newObject(Reflexive.class);
child.setName("childB"+i);
child.setToParent(parent);
try {
context.commitChanges();
} catch (final Exception e) {
errors++;
e.printStackTrace();
context.rollbackChanges();
}
}
// then no error occurred
assertEquals(String.format("Failed on %s of %s attempts.", errors,
attempts), 0, errors);
}
{code}
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