CriteriaBuilder Many-to-one restriction on id

When doing string based queries it is possible to use the "id" keyword on a many-to-one attribute e.g.:

from Enrolment where person.id=:personId

In this case this would generate sql:

select * from enrolment where person_id=?

How do I achieve the same using the CriteriaBuilder?

CriteriaQuery<Enrolement> query = criteriaBuilder.createQuery(Enrolement.class);
Root<Enrolement> root = query.from(Enrolment.class);
query.select(root);

// Does not work
query.where(criteriaBuilder.equal(root.get("person.id"), 1L));

// Does not work
query.where(criteriaBuilde开发者_JAVA百科r.equal(root.get("person").root.get("personId"), 1L));

I imagine you could join to person and add a restrict to the person root but that strikes me as overkill.

This worked for me in a similar setup:

criteriaBuilder.equal( datasheetRoot.get( Datasheet_.componentSubtype )
                                    .get( ComponentSubtype_.id ), 
                       componentSubtypeId );

(This is using Spring boot 1.0.1 with Spring Data JPA 1.5.1 and Hibernate 4.3.1)

My root is Datasheet which has a @ManyToOne to a ComponentSubtype which in turn has an id.

After trial-and-error the following works:

query.where(criteriaBuilder.equal(root.get("person"), 1L));

I guess I have been writing string based queries for so long I couldn't see the wood for the trees. It would be nice if the two ways of writing queries was consistent:

from Enrolement where person=1L (does not work)