Spring Rest Hibernate创建嵌套对象

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

    private String name;

    @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL)
    private List<Child> children;

    // getters and setters
}

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

    private String name;

    @ManyToOne
    @JoinColumn(name = "parent_id")
    private Parent parent;

    // getters and setters
}

@RestController
@RequestMapping("/parents")
public class ParentController {
    @Autowired
    private ParentRepository parentRepository;

    @GetMapping("/{id}")
    public Parent getParent(@PathVariable Long id) {
        return parentRepository.findById(id).orElse(null);
    }

    @PostMapping
    public Parent createParent(@RequestBody Parent parent) {
        return parentRepository.save(parent);
    }

    // other methods
}

@Configuration
@EnableTransactionManagement
public class HibernateConfig {
    @Bean
    public LocalSessionFactoryBean sessionFactory() {
        LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
        sessionFactory.setDataSource(dataSource());
        sessionFactory.setPackagesToScan("com.example.model");
        sessionFactory.setHibernateProperties(hibernateProperties());
        return sessionFactory;
    }

    @Bean
    public DataSource dataSource() {
        // configure and return the data source
    }

    @Bean
    public PlatformTransactionManager transactionManager(SessionFactory sessionFactory) {
        HibernateTransactionManager transactionManager = new HibernateTransactionManager();
        transactionManager.setSessionFactory(sessionFactory);
        return transactionManager;
    }

    private Properties hibernateProperties() {
        // configure and return Hibernate properties
    }
}