java定制JPA CriteriaQuery的onclause

Question

有没有办法通过添加一些表达式来进一步限制联接？我用纯sql编写：

SELECT c.*, COUNT(i.id) invoice_count
FROM customers c
LEFT JOIN invoices i ON i.customer_id = c.id
    AND i.creation_time >= '2012-01-01' -- <= extra restriction
    AND i.creation_time < '2013-01-01' -- <= extra restriction
GROUP BY c.id

我还没有找到用JPA2.0 CriteriaQuery实现这一点的方法

更新：根据要求，我的（简化）代码（无额外限制）：

CriteriaQuery<CustomerAndInvoiceCount> criteriaQuery = criteriaBuilder.createQuery(CustomerAndInvoiceCount.class);

Root<Customer> customer = criteriaQuery.from(Customer.class);
ListJoin<Customer, Invoice> invoices = customer.join(Customer_.invoices, JoinType.LEFT);

criteriaQuery.select(criteriaBuilder.construct(
        CustomerAndInvoiceCount.class,
        customer,
        criteriaBuilder.count(invoices)));
criteriaQuery.groupBy(customer);

Answer 1

您应该能够添加条件谓词，而不必担心它们是ON子句还是WHERE子句的一部分