如何使用Spring Boot更新MongoDB集合中的子对象？

@Document(collection = "parents")
public class Parent {
    @Id
    private String id;
    private List<Child> children;

    // getters and setters
}

public class Child {
    private String name;
    private int age;

    // getters and setters
}

public interface ParentRepository extends MongoRepository<Parent, String> {
    
}

@Service
public class ParentService {
    @Autowired
    private ParentRepository parentRepository;
    
    public void updateChild(String parentId, String childId, Child updatedChild) {
        Optional<Parent> optionalParent = parentRepository.findById(parentId);
        if (optionalParent.isPresent()) {
            Parent parent = optionalParent.get();
            List<Child> children = parent.getChildren();
            for (Child child : children) {
                if (child.getId().equals(childId)) {
                    child.setName(updatedChild.getName());
                    child.setAge(updatedChild.getAge());
                    break;
                }
            }
            parent.setChildren(children);
            parentRepository.save(parent);
        }
    }
}