/** This test provides an example of testing whether the collection is empty */
@Test
public void testIsEmpty() {
log.info("*** testIsEmpty() ***");
CriteriaBuilder cb = em.getCriteriaBuilder();
{
CriteriaQuery<Clerk> qdef = cb.createQuery(Clerk.class);
// select c from Clerk c
// where c.sales IS EMPTY
Root<Clerk> c = qdef.from(Clerk.class);
qdef.select(c).where(cb.isEmpty(c.<List<Sale>>get("sales")));
int rows = executeQuery(qdef).size();
assertEquals("unexpected number of rows", 1, rows);
}
{
CriteriaQuery<Clerk> qdef = cb.createQuery(Clerk.class);
// select c from Clerk c
// where c.sales IS NOT EMPTY
Root<Clerk> c = qdef.from(Clerk.class);
qdef.select(c).where(cb.isNotEmpty(c.<List<Sale>>get("sales")));
int rows = executeQuery(qdef).size();
assertEquals("unexpected number of rows", 2, rows);
}
}
@Override
public <T> Predicate execute(CriteriaBuilder cb, Root<T> p, String field, X value) {
return cb.isNotEmpty(p.<Collection<X>>get(field));
}