JPA Criteria API: Multiple condition on LEFT JOIN

Question

I have a join reference like following for which the first join expression is constructed by the JPA API automatically.

CriteriaBuilder cb = entityManager.ge         


        

Answer 1

And Hibernate's Criteria API version 3.6 supports it too:

    Criteria c = session.createCriteria(Tuple.class);

    c.createAlias("demands", "d")
    .createAlias("d.metadata", "m", 
        Criteria.LEFT_JOIN, Restrictions.eq("m.type", "AFFECTATION_KEY"));

Or you may want Restrictions.eqProperty() for that last bit. Note the under-appreciated version of createAlias() with the fourth parameter. Here is a quote from the documentation

Parameters:

• associationPath - A dot-seperated property path
• alias - The alias to assign to the joined association (for later reference).
• joinType - The type of join to use.
• withClause - The criteria to be added to the join condition (ON clause)

Hibernate API 3.6