Spring Data JPA：如何不在countQueries中重复自己？

Question

我正在使用Spring Data JPA存储库（1.7.2），通常遇到以下情况：

• 实体具有延迟加载的集合
• 有时会急切地获取这些集合（通过JPAQL fetch join）
• 存储库通常返回Page<Foo>而不是List<Foo>

我需要提供countQuery给@Query在返回的存储库中使用提取联接的每个对象Page。此问题已在此StackOverflow问题中进行了讨论

我典型的存储库方法如下所示：

@Query(value = "SELECT e FROM Employee e LEFT JOIN FETCH e.addresses a " +
    "WHERE e.company.id = :companyId " +
    "AND e.deleted = false " +
    "AND e.primaryAddress.deleted = false " +
    "ORDER BY e.id, a.id",
    countQuery="SELECT count(e) FROM Employee e WHERE e.companyId = :companyId AND e.deleted = false AND e.primaryAddress.deleted = false"
)
Page<Employee> findAllEmployeesWithAddressesForCompany(@Param("companyId") long companyId, Pageable pageable);

显然，它不是很干。您可以说我在value和countQuery参数中都重复了所有条件。我如何在这里保持干燥？

Answer 1

你可以做这样的事情

public interface MyRepository extends JpaRepository {

    public static final String WHERE_PART = "e.companyId = :companyId AND e.deleted = false AND e.primaryAddress.deleted = false ";

    @Query(value = "SELECT e FROM Employee e LEFT JOIN FETCH e.addresses a " +
        "WHERE " + MyRepository.WHERE_PART
        "ORDER BY e.id, a.id",
        countQuery="SELECT count(e) FROM Employee e WHERE " + MyRepository.WHERE_PART
    )
    Page<Employee> findAllEmployeesWithAddressesForCompany(@Param("companyId") long companyId, Pageable pageable);