JPQL多次连接获取返回错误“不能同时获取多个包”

Question

我正在学习Spring。

我在处理JPQL问题上有问题。我上帝有三个实体。

public class Cheat implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "cheat_seq", length = 10)
    private Long cheatSeq;

    @OneToMany(mappedBy = "cheat", fetch=FetchType.LAZY)
    private List<CheatGoodVote> goodVote;

    @OneToMany(mappedBy = "cheat", fetch=FetchType.LAZY)
    private List<CheatBadVote> badVote;

    // skipped.
}

其他的是映射到上面实体的实体。

public class CheatGoodVote {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="vote_seq", length=10)
    private Long voteSeq;

    @ManyToOne(cascade=CascadeType.ALL)
    @JoinColumn(name="cheat_fk", referencedColumnName="cheat_seq")
    public Cheat cheat;

    // ..skipped
}

两个实体几乎是相同的。

public class CheatBadVote {    
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="vote_seq", length=10)
    private Long voteSeq;

    @Column(name="ip_address", nullable=false)
    private String ipAddress;

    @Column(name="reg_date", nullable=false)
    private Date regDate;

    @ManyToOne(cascade=CascadeType.ALL)
    @JoinColumn(name="cheat_fk", referencedColumnName="cheat_seq")
    public Cheat cheat;

}

当我调用JPQL “@Query”(“从作弊c选择c+加入获取c.goodVote连接获取c.badVote c.goodVote(c.goodVote) <= :voteCnt")"，

它返回错误：

Caused by: org.hibernate.loader.MultipleBagFetchException: cannot simultaneously fetch multiple bags: [com.aibiigae1221.skyQuiz.data.entity.Cheat.goodVote, com.aibiigae1221.skyQuiz.data.entity.Cheat.badVote]
    at org.hibernate.loader.BasicLoader.postInstantiate(BasicLoader.java:75) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.loader.hql.QueryLoader.<init>(QueryLoader.java:106) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:210) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:141) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:115) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:77) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:153) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:553) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:662) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    ... 103 common frames omitted

我想要一起作弊，CheatGoodVote，CheatBadVote。错误是来自jpql问题吗？还是我的实体映射是错的？

Answer 1

它似乎是与框架相关的bug。取决于您的hibernate版本。

考虑一下这个问题，看起来像你的链接

笛卡尔积

请注意，连接获取这两种选择，最终将得到两者的笛卡尔积。有关问题本身和解决方案的更多信息，请访问这里