JPA Criteria API predicates for objects in OneToMany relationship - jpa

Question

Given the following code
#Entity
public class Invoice {
#GeneratedValue(strategy = GenerationType.AUTO)
#Id
public Long id;
#Embedded
private InvoiceData data = new InvoiceData();
}
#Embeddable
public class InvoiceData {
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
public Collection<InvoiceLineItem> lineItems;
}
#Entity
public abstract class InvoiceLineItem {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#Column
private String description;
}
#Entity
public class GoodsLineItem extends InvoiceLineItem {
}
#Entity
public class CostLineItem extends InvoiceLineItem {
}
How would I write a criteria api query that returns all Invoices with a CostLinesItem that's description is 'TAX'?
I am using the metadata API. I have tried various approaches most of which are variations of the 2 listed below. Any pointers/help or 'go read this's will be greatly appreciated.
Attempt 1 (of many):
#Test
public void criteria_api_and_collections() throws Exception {
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<Invoice> query = builder.createQuery(Invoice.class);
Root<Invoice> root = query.from(Invoice.class);
Join<InvoiceData, InvoiceLineItem> lineItems = root.join(Invoice_.data).join(InvoiceData_.lineItems);
query.where(builder.equal(lineItems.get(InvoiceLineItem_.description), ""));
List<Invoice> resultList = em.createQuery(query).getResultList();
System.out.println(resultList);
}
Attempt 2 (of a many):
#Test
public void criteria_api_and_collections() throws Exception {
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<Invoice> query = builder.createQuery(Invoice.class);
Root<Invoice> root = query.from(Invoice.class);
Join<InvoiceData, InvoiceLineItem> lineItems = root.join(Invoice_.data).join(InvoiceData_.lineItems, JoinType.LEFT);
Subquery<CostLineItem> subquery = query.subquery(CostLineItem.class);
Root<CostLineItem> fromLineItem = subquery.from(CostLineItem.class);
subquery.select(fromLineItem);
subquery.where(builder.equal(lineItems.get(InvoiceLineItem_.description), "TAX"));
query.where(builder.in(lineItems).value(subquery));
List<Invoice> resultList = em.createQuery(query).getResultList();
}
Both attempts causes a SQL grammer Exception. An alias is referred to in the resulting SQL that is never created. It looks like the alias should have been assigned to a join in the SQL that does not exist. In other words the InvoiceLineItems are not fetched in the query.

Answer 1

I am not able to make a test right now, but sticking to the Java EE 6 Tutorial, we see that
Embeddable classes may also contain relationships to other entities or
collections of entities. If the embeddable class has such a
relationship, the relationship is from the target entity or collection
of entities to the entity that owns the embeddable class.
This makes me think that the Join Predicate should be defined with the starting Entity Invoice instead of InvoiceData. And this is supported also by the fact that normally the starting Entity should be the query root itself. I would try with something like this:
Join<Invoice, InvoiceLineItem> lineItems = root.join(Invoice_.data).join(InvoiceData_.lineItems);

Answer 2

I swapped out Hibernate 4.1.0.Final for EclipseLink 2.0.0 and it worked.