@Test
public void avg() {
EntityManager entityManager = factory.createEntityManager();
CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<Double> query = builder.createQuery(Double.class);
Root<Employee> root = query.from(Employee.class);
query.select(builder.avg(root.get(Employee_.age)));
Double min = entityManager.createQuery(query).getSingleResult();
assertEquals(new Double(35.625), min);
}
/** This test provides a demonstration of the SUM and AVE aggregate functions */
@Test
public void testSumAve() {
log.info("*** testSumAve() ***");
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Number> qdef = cb.createQuery(Number.class);
Root<Sale> s = qdef.from(Sale.class);
// select sum(s.amount) from Sale s
qdef.select(cb.sum(s.<BigDecimal>get("amount")));
List<Number> results = executeQuery(qdef);
assertEquals("unexpected number of rows", 1, results.size());
assertEquals("unexpected result", 250, results.get(0).intValue());
// select avg(s.amount) from Sale s
qdef.select(cb.avg(s.<BigDecimal>get("amount")));
results = executeQuery(qdef);
assertEquals("unexpected number of rows", 1, results.size());
assertEquals("unexpected result", 125, results.get(0).intValue());
}
@SuppressWarnings("unchecked")
@Override
public <R> Selection<X> toSelection(
CriteriaQuery<R> query, CriteriaBuilder builder, Path<? extends P> path) {
return (Selection<X>) builder.avg(path.get(attribute));
}