如何隐藏“孩子”：在spring boot中从一对多关系中的最后一个孩子开始

@Entity
public class Parent {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    // 其他属性和关联关系

    // Getter和Setter方法
}

@Entity
public class Child {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    // 其他属性和关联关系

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "parent_id")
    private Parent parent;

    // Getter和Setter方法
}

public interface ParentRepository extends JpaRepository<Parent, Long> {
}

public interface ChildRepository extends JpaRepository<Child, Long> {
}

@Service
public class ParentService {
    private final ParentRepository parentRepository;

    public ParentService(ParentRepository parentRepository) {
        this.parentRepository = parentRepository;
    }

    // 其他方法
}

@Service
public class ChildService {
    private final ChildRepository childRepository;

    public ChildService(ChildRepository childRepository) {
        this.childRepository = childRepository;
    }

    // 其他方法
}

@RestController
@RequestMapping("/parents")
public class ParentController {
    private final ParentService parentService;

    public ParentController(ParentService parentService) {
        this.parentService = parentService;
    }

    // 其他方法
}

@RestController
@RequestMapping("/children")
public class ChildController {
    private final ChildService childService;

    public ChildController(ChildService childService) {
        this.childService = childService;
    }

    // 其他方法
}

@PutMapping("/{parentId}/hide-last-child")
public ResponseEntity<String> hideLastChild(@PathVariable Long parentId) {
    Optional<Parent> optionalParent = parentService.findById(parentId);
    if (optionalParent.isPresent()) {
        Parent parent = optionalParent.get();
        List<Child> children = parent.getChildren();
        if (!children.isEmpty()) {
            Child lastChild = children.get(children.size() - 1);
            lastChild.setParent(null);
            childService.save(lastChild);
        }
        return ResponseEntity.ok("Successfully hidden the last child.");
    } else {
        return ResponseEntity.notFound().build();
    }
}