Continuous Development Blog

you can read first part from JPA Criteria API by samples – Part-I

some more examples with JPA criteria API

Simple Join query

        long category=200L;
        Query query = entityManager.createQuery("select s from OrderItem s " +
        		"where s.product.category=:cat");
        query.setParameter("cat", category);
        List<OrderItem> list = query.getResultList();

        CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
        CriteriaQuery<Object> criteriaQuery = criteriaBuilder.createQuery();
        Root<OrderItem> from = criteriaQuery.from(OrderItem.class);
        Path<Object> path = from.join("product").get("category");

        CriteriaQuery<Object> select = criteriaQuery.select(from);
        select.where(criteriaBuilder.equal(path, category));

        TypedQuery<Object> typedQuery = entityManager.createQuery(select);
        List<Object> resultList = typedQuery.getResultList();
        assertEqualsList(list, resultList);

simple fetch join query

        long category=200L;
        Query query = entityManager.createQuery("select s from OrderItem s " +
        		"join fetch s.product where s.product.category=:cat");
        query.setParameter("cat", category);
        List<OrderItem> list = query.getResultList();

        CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
        CriteriaQuery<Object> criteriaQuery = criteriaBuilder.createQuery();
        Root<OrderItem> from = criteriaQuery.from(OrderItem.class);
        Path<Object> path = from.join("product").get("category");

        from.fetch("product"); //FETCH product

        CriteriaQuery<Object> select = criteriaQuery.select(from);
        select.where(criteriaBuilder.equal(path, category));

        TypedQuery<Object> typedQuery = entityManager.createQuery(select);
        List<Object> resultList = typedQuery.getResultList();
        assertEqualsList(list, resultList);

subselect (subquery) join query

         Query query = entityManager.createQuery(
                "select s from OrderItem s join fetch s.product" +
                " where s.product.category in" +
                " (select sb.pbyte from SimpleBean sb where sb.pint>=30000)");

        List<OrderItem> list = query.getResultList();

        CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
        CriteriaQuery<Object> criteriaQuery = criteriaBuilder.createQuery();
        Root<OrderItem> from = criteriaQuery.from(OrderItem.class);
        Path<Object> path = from.join("product").get("category");
        from.fetch("product");
        CriteriaQuery<Object> select = criteriaQuery.select(from);

        Subquery<SimpleBean> subquery = criteriaQuery.subquery(SimpleBean.class);
        Root fromSimpleBean = subquery.from(SimpleBean.class);
        subquery.select(fromSimpleBean.get("pbyte"));
        subquery.where(criteriaBuilder.ge(fromSimpleBean.get("pint"),30000));
        select.where(criteriaBuilder.in(path).value(subquery));

        TypedQuery<Object> typedQuery = entityManager.createQuery(select);
        List<Object> resultList = typedQuery.getResultList();
        assertEqualsList(list, resultList);