How to return list of key/value pair maps from JPQL query using EclipseLink?

Question

I have tried this solution:

List<javax.persistence.Tuple> result = entityManager.createQuery("select f.Id as Id, f.Project as Project from FirewallRequest f", javax.persistence.Tuple.class)
                                                    .getResultList();
result.get(0).get("Project");

I'm getting this:

java.lang.ClassCastException: class [Ljava.lang.Object; cannot be cast to class javax.persistence.Tuple ([Ljava.lang.Object; is in module java.base of loader 'bootstrap'; javax.persistence.Tuple is in unnamed module of loader java.net.URLClassLoader @7a9273a8)

So it seems to be returning List of Objects instead of Tuples. Is Tuple not supported by EclipseLink or what is the problem?

Debugger shows it's actually a Vector of Objects:

I'm using TomEE 8 which uses EclipseLink 2.7.4.v20190115 for JPA. I could try with JPA Criteria Query but I'm converting from SQL and it would be easier to convert it to JPQL.

Edit 1

Here is an answer from writer of the linked article which also suggests this should work.

Edit 2

EclipseLink issue created.

Edit 3

Luckily it works with JPA Criteria Query (CriteriaBuilder#createTupleQuery()). It's more work to convert SQL to that but at least it works.

score 0 · Answer 1 · answered Apr 25 '20 at 10:18

0

A query with projection returns always List<Object[]>

As long as you don't use constructor expression with

select new x.y.Tuple(f.Id, f.Project) from FirewallRequest f

But then you need a Tuple with a constructor that matches the projection.

answered Apr 25 '20 at 10:18

Simon Martinelli

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So the code in the linked example (which even has asserts) would never work? – Panu Haaramo Apr 25 '20 at 10:21
It seems that EclipseLink does not support it. – Simon Martinelli Apr 25 '20 at 10:24
OK that's what I thought, would work with Hibernate. – Panu Haaramo Apr 25 '20 at 10:26
Oh I just see another issue. Is Project an Entity? – Simon Martinelli Apr 25 '20 at 10:29
No, it's a String field in entity. – Panu Haaramo Apr 25 '20 at 10:30
I tried with Hibernate and it works. Can you try to use the newest EclipseLink version? – Simon Martinelli Apr 25 '20 at 10:45
That's quite new and it's bundled with TomEE. I can investigate. – Panu Haaramo Apr 25 '20 at 10:46
I was able to upgrade to latest 2.7.6 with Maven dependency but it did not help. – Panu Haaramo Apr 25 '20 at 10:52
Tried to switch to Hibernate but I always get `ClassNotFoundException: org.hibernate.ejb.HibernatePersistence` in spite of having all required dependencies. – Panu Haaramo Apr 25 '20 at 11:21

How to return list of key/value pair maps from JPQL query using EclipseLink?

1 Answers1