在我的spring启动应用程序中，有一个模型“item”，它有sefl引用。我想实现按字段排序器的排序，但我不知道如何为crud操作实现它。例如，如何在将实体保存到存储库之前获取sortorder的值，以及如何在更新实体之后重新计算sortorder。任何帮助都将不胜感激！谢谢！

@Data
@Entity
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "item")
public class Item {

    @Id
    @JsonFormat(shape = JsonFormat.Shape.STRING)
    @SequenceGenerator(name = "itemSeq", sequenceName = "item_id_seq", allocationSize = 50)
    @GeneratedValue(strategy = GenerationType.IDENTITY, generator = "itemSeq")
    private Long id;

    @NotBlank
    @Column(name = "name")
    private String name;

    @Column(name = "description")
    private String description;

    @Column(name = "sort_order")
    private String sortOrder;

    @Column(name = "is_active")
    private Boolean isActive;

    @ManyToOne
    @JoinColumn(name = "parent_id")
    @JsonFormat(shape = JsonFormat.Shape.STRING)
    @JsonIgnoreProperties({"name", "description", "sortOrder", "isActive", "parent", "children"})
    private Item parent;

    @OneToMany(mappedBy = "parent", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @Where(clause = "is_active = true")
    @Fetch(FetchMode.SUBSELECT)
    @OrderBy("sort_order ASC")
    private List<Item> children = new ArrayList<>();
}