Spring Data中的分页+ @Query + JOIN获取？不起作用

如何解决Spring Data中的分页+ @Query + JOIN获取？不起作用

我正在尝试使用Spring Data中的Pageable批注将排序字段上的@Query集成到一起。

第一个接口的方法（不带@Query但带Pageable）的作用就像是一个超级按钮。就像当我仅使用@Query来获取一名Employee时一样，但是我使用的是Pageable而不是Optional<Employee>（第3种方法）。 但是 当我尝试将这两者合而为一时，乐趣就开始了。

当我尝试按name字段对数据进行排序时，它会发出以下错误消息：

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

所以问题是：如何告诉spring在联接字段中寻找name ？如何使用Spring Data做到这一点？

我已经尝试了几种方法，但是它们没有起作用，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，以便在某种程度上与分页（spring data jpa @query and pageable）相符
• 我已关注Baeldung's tutorial，但这并不涵盖联接
• Spring-Data FETCH JOIN with Paging is not working也建议使用countQuery，但我宁愿坚持使用Page<Employee>而不是List<Employee>。

我将在下面留下一些代码示例。如果我省略了一些重要的内容，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,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,String sortColumn) {
        Page<EmployeeDTO> employeePage = employeeRepository.getEmployeeDetails(status,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,String sortDirection,String sortColumn) {
    try {
        EmployeeResponse employeeResponse = employeeService.getEmployeesByStatus(status,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();
    }
}

解决方法

尝试下面的代码。

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);

在这里，我们试图通知JPA该名称是Employee表的外键。