Hibernate Envers get revisions for criteria

Question

Using Hibernate Envers (4.1.9.Final). Trying to get all the revisions (date, revision number) for which a entities have changed of a certain type and that match a certain criterion.

This is the code that I'm currently having:

    AuditReader auditReader = AuditReaderFactory.get(entityManager);
    AuditQuery query = auditReader.createQuery()
            .forRevisionsOfEntity(InventoryItem.class, false, true)
            .add(AuditEntity.property("section_uuid").eq(sectionUuid))
            .addOrder(AuditEntity.revisionNumber().desc());
    List<Object[]> revisions = query.getResultList();

1. This returns one element for each changed InventoryItem. So, if two InventoryItems were changed in a revision, I get two elements -- I do not want that.
2. This returns also the actual InventoryItems, I think that's a bit heavy -- I do not want that.

How can I get a distinct collection of revisions (date, revision number)?

Answer 1

I think what you are looking for is the addProjection method on AuditQuery. You can add a projection on the revision number and date.

Answer 2

On basis of Adam's answer, here is the code that I implemented. I'll mark his answer as the accepted answer.

AuditReader auditReader = AuditReaderFactory.get(entityManager);
AuditQuery query = auditReader.createQuery()
    .forRevisionsOfEntity(InventoryItem.class, false, true)
    .addProjection(AuditEntity.revisionNumber().distinct())
    .addProjection(AuditEntity.revisionProperty("created"))
    .add(AuditEntity.property("section_uuid").eq(sectionUuid))
    .addOrder(AuditEntity.revisionNumber().desc());

As a result, query.getResultList() will return a collection of Object[], where each Object[] contains:

• Object[0]: revision number as int
• Object[1]: revision date as java.util.Date, corresponding the created revisionProperty