Spring Data JPA从OneToMany关系按值排序

Question

我正在尝试按嵌套的集合元素值对结果进行排序。我有一个非常简单的模型：

@Entity
public class User {

    @Id
    @NotNull
    @Column(name = "userid")
    private Long id;

    @OneToMany(mappedBy = "user")
    private Collection<Setting> settings = new HashSet<>();

    // getters and setters
}

@Entity
public class Setting {

    @Id
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "userid")
    private User user;

    private String key;
    private String value;

    // getters and setters
}

public interface UserRepository extends JpaRepository<User, Long>, QuerydslPredicateExecutor<User> {
}

我希望返回的结果是按一个设置值排序的。使用Spring Data JPA和QueryDSL可以按settings.name = 'SampleName‘的user.settings.value排序吗？

Answer 1

我用过JpaSpecificationExecutor。让我们以findAll为例。

Page<T> findAll(@Nullable Specification<T> spec, Pageable pageable);

在调用此方法之前，您可以使用动态Sort信息动态创建规范(where条件)和Pageable对象。

例如

...

Specification<T> whereSpecifications = Specification.where(yourWhereSpeficiation);
Sort sortByProperty = Sort.by(Sort.Order.asc("property"));
PageRequest orderedPageRequest = PageRequest.of(1, 100, sortByProperty);

userRepository.findAll(whereSpecifications, PageRequest.of(page, limit, orderedPageRequest));