Olivier Paquet created OPENJPA-2545:
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Summary: Joining Entites results in multiple occurences of tables
in FROM clause
Key: OPENJPA-2545
URL: https://issues.apache.org/jira/browse/OPENJPA-2545
Project: OpenJPA
Issue Type: Question
Components: criteria, jpa
Affects Versions: 2.3.0
Reporter: Olivier Paquet
Priority: Blocker
Hi,
We use the Criteria API with OpenJPA to execute complex searches.
But currently I'm blocked and as I found nothing on the web or your site I
wanted to ask you directly:
We have several Entites, let's say A, B, C
Currenlty we do a LEFT JOIN between A and B to get all A Entities even if there
is no relation to B, it's working fine as expected.
Now we have another relation between B and C. B has just a String which
represents the FK to C, so I wanted to join between B and C.
{code}
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Object[]> query = cb.createQuery(Object[].class);
Root<A> clRun = query.from(A.class);
Join<A, B> bJoin = clRun.join("clearingFiles",
JoinType.LEFT);
query.where(cb.equal(clRun.get("status"),
ClearingRunStatus.PROCESSED));
query.select(cb.array(clRun, bJoin ));
TypedQuery<Object[]> q = em.createQuery(query);
List<Object[]> result = q.getResultList();
{code}
{code}
SELECT ...
FROM A t0, B t1, A t2
WHERE (t2.STATUS = 'PROCESSED') AND t0.CLEARING_RUN_ID = t1.CLEARING_RUN_ID(+)
{code}
So without the cb.equal, A is present 1 time -> OK
But once I add an additiona comparison to one of the attributes from A, it add
the Table a second time to the query, which generates a very big join and will
crash our application.
So please, is this a Bug or do I use it in a wrong way?
Greetings, Olivier
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