Spring Data 中的 Pageable + @Query + JOIN (fetch?) 不起作用

Question

我正在尝试使用 Spring Data 中的 @Query 注释在连接字段上将排序与 Pageable 集成。

第一个接口的方法（没有@Query，但有Pageable）就像一个魅力。就像我只使用@Query 获取一名员工时一样，但我使用Pageable 而不是Optional<Employee> 那里（第三种方法）。 但是当我尝试将这两者合二为一时，乐趣就开始了——它不再起作用了。

当我尝试按 name 字段对数据进行排序时，它会报错：

Caused by: org.hibernate.QueryException: could not resolve property: name of: (....).model.employee.Employee

所以问题是：如何告诉 spring 在连接字段中查找 name？如何使用 Spring Data 做到这一点？

我已经尝试了几件事，但它们都不起作用或者我仍然不知道如何正确使用它们：

• 有人建议将countQuery 添加到@Query 参数中，这样这与分页（spring data jpa @query and pageable）以某种方式对应
• 我关注了Baeldung's tutorial，但这不包括连接
• Spring-Data FETCH JOIN with Paging is not working 也建议使用countQuery，但我更愿意坚持使用Page<Employee> 而不是List<Employee>。

我将在下面留下一些代码示例。如果我遗漏了重要的内容，请随时要求更新。

// Employee
@Entity
@Table(name = "employee", schema = "emp")
@Data
@NoArgsConstructor
public class Employee {
    private static final String SEQUENCE = "EMPLOYEE_SEQUENCE";

    @Id
    @SequenceGenerator(sequenceName = SEQUENCE, name = SEQUENCE, allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = SEQUENCE)
    private Long id;

    @Column(name = "employee_number")
    private String employeeNumber;

    @Column
    @Enumerated(EnumType.STRING)
    private EmployeeStatus status;

    @OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @Audited(targetAuditMode = RelationTargetAuditMode.NOT_AUDITED)
    @JoinColumn(name = "id_details")
    private Details details;

    // some other fields ...
}

// Details
@Entity
@Table(name = "details", schema = "emp")
@Data
@NoArgsConstructor
public class Details {
    private static final String SEQUENCE = "DETAILS_SEQUENCE";

    @Id
    @SequenceGenerator(sequenceName = SEQUENCE, name = SEQUENCE, allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = SEQUENCE)
    private Long id;

    private String name;

    private String surname;

    // some other fields ...
}

// EmployeeDTO
@NoArgsConstructor
@AllArgsConstructor
@Data
@Builder(toBuilder = true)
public class EmployeeDTO {
    private Long id;
    private String employeeNumber;
    private String status;
    private String name;
    private String surname;

    // some other fields ...
}

// EmployeeRepository
@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long> {

    // 1st method
    Page<Employee> findByStatus(EmployeeStatus status, Pageable pageable);

    // 2nd method
    @Query(value = "select e from Employee e join e.details where e.status = :status",
            countQuery = "select count(*) from Employee e join e.details where e.status = :status")
    Page<Employee> getEmployeeDetails(@Param("status") EmployeeStatus status, Pageable pageable);

    // 3rd method
    @Query("select e from Employee e join fetch e.details where e.id = :id")
    Optional<Employee> findByIdWithDetails(Long id);

    // ...
}

// EmployeeService
@Service
public class EmployeeService {

    private final EmployeeRepository employeeRepository;
    private final EntityDtoConverter entityDtoConverter;

    @Autowired
    public EmployeeService(EmployeeRepository employeeRepository, EntityDtoConverter entityDtoConverter) {
        this.employeeRepository = employeeRepository;
        this.entityDtoConverter = entityDtoConverter;
    }

    public EmployeeResponse getEmployeesByStatus(EmployeeStatus status, int pageSize, int pageIndex, Sort.Direction sortDirection, String sortColumn) {
        Page<EmployeeDTO> employeePage = employeeRepository.findByStatus(status, PageRequest.of(pageIndex, pageSize, Sort.by(sortDirection, sortColumn)))
                .map(entityDtoConverter::convertEmployeeBaseToDto);
        return new EmployeeResponse(employeePage);
    }

    public EmployeeResponse getEmployeeDetails(EmployeeStatus status, int pageSize, int pageIndex, Sort.Direction sortDirection, String sortColumn) {
        Page<EmployeeDTO> employeePage = employeeRepository.getEmployeeDetails(status, PageRequest.of(pageIndex, pageSize, Sort.by(sortDirection, sortColumn)))
                .map(entityDtoConverter::convertToEmployeeWithDetailsDto);
        return new EmployeeResponse(employeePage);
    }

    // ...
}

// EntityDtoConverter
@Component
public class EntityDtoConverter {

    public EmployeeDTO convertEmployeeBaseToDto(Employee entity) {
        return EmployeeDTO.builder()
                .id(entity.getId())
                .employeeNumber(entity.getEmployeeNumber())
                .status(entity.getStatus())
                .build();
    }

    public EmployeeDTO convertToEmployeeWithDetailsDto(Employee entity) {
        return convertEmployeeBaseToDto(entity).toBuilder()
                .name(entity.getDetails().getName())
                .surname(entity.getDetails().getSurname())
                .build();
    }

    // ...
}

编辑：

这是我的rest控制器的方法之一：

@GetMapping
public ResponseEntity<EmployeeResponse> getEmployeesByStatus(EmployeeStatus status, int pageSize, int pageIndex, String sortDirection, String sortColumn) {
    try {
        EmployeeResponse employeeResponse = employeeService.getEmployeesByStatus(status, pageSize, pageIndex, Sort.Direction.fromString(sortDirection), sortColumn);
        return employeeResponse.getTotalElements().equals(0L) ? ResponseEntity.noContent().build() : ResponseEntity.ok(employeeResponse);
    } catch (Exception e) {
        log.error(ERROR_MESSAGE, e);
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).build();
    }
}

Answer 1

试试下面的代码。

Specification<Employee> joins = (employee, query, cb) ->  {
            Join<Employee, Detail> details = employee.join("details");

            return cb.and(
                    employee.equal(employee.get("name", name)),
                    details.equal(details.get("name", detailName))
            );
        };

        PageRequest pageRequest = new PageRequest(0, 2, new Sort(Sort.Direction.DESC, "name"));

        Page<Employee> customerPage = employeeRepository.findAll(joins, pageRequest);

这里我们试图通知 JPA 这个名称是 Employee 表的外键。