java - Spring Boot JPA - OneToMany 关系导致无限循环

Question

我有两个具有简单@OneToMany 关系的对象，如下所示:

parent :

@Entity
public class ParentAccount {

  @Id
  @GeneratedValue
  private long id;
  private String name;

  @OneToMany(fetch = FetchType.EAGER, mappedBy = "parentAccount")
  private Set<LinkedAccount> linkedAccounts;

}

child :

@Entity
public class LinkedAccount {

  @Id
  @GeneratedValue
  private long id;

  @ManyToOne(optional = false)
  private ParentAccount parentAccount;

  private String name;

  // empty constructor for JPA
  public LinkedAccount() {
  }

}

我将使用 Spring CrudRepository 来操作这些实体。然而，当调用 ParentAccount parent = parentAccountRepository.findOne(id); 时，某种无限循环开始发生并且 hibernate 在整个控制台中发送垃圾邮件:

Hibernate: select linkedacco0_.parent_account_id as parent_a6_1_0_, linkedacco0_.id as id1_0_0_, linkedacco0_.id as id1_0_1_, linkedacco0_.aws_id as aws_id2_0_1_, linkedacco0_.key_id as key_id3_0_1_, linkedacco0_.name as name4_0_1_, linkedacco0_.parent_account_id as parent_a6_0_1_, linkedacco0_.secret_key as secret_k5_0_1_ from linked_account linkedacco0_ where linkedacco0_.parent_account_id=?

我尝试将获取类型更改为 LAZY，但随后出现此错误:

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.berrycloud.scheduler.model.ParentAccount.linkedAccounts, could not initialize proxy - no Session

(看起来它试图在事务上下文之外进行延迟加载)。

这是我的 CRUD 存储库:

@Repository
public interface ParentAccountRepository extends CrudRepository<ParentAccount, Long> {
}

有人能告诉我如何解决这个问题吗？我更喜欢使用 EAGER fetch 的解决方案。感谢您的任何提示

编辑:这是我正在使用的模式

CREATE TABLE parent_account (
    id BIGINT auto_increment,
    name VARCHAR(80) null,
    PRIMARY KEY (`id`)
);

CREATE TABLE linked_account (
    id BIGINT auto_increment,
    parent_account_id BIGINT,
    name VARCHAR(80) null,
    FOREIGN KEY (`parent_account_id`) REFERENCES `parent_account` (`id`),
    PRIMARY KEY (`id`)
);

Answer 1

正如第一个答案所暗示的:

Do not use Lombok's @Data annotation on @Entity classes.

原因 @Data 生成hashcode()、equals() 和toString() 使用生成的 getter 的方法。使用 getter 意味着获取新数据，即使该属性标记为 FetchType=LAZY。

hibernate 在某处尝试使用 toString() 记录数据，但它崩溃了。