嵌入式ID映射失败，出现DescriptorException：应为主键字段EclipseLink定义一个非只读映射

如何解决嵌入式ID映射失败，出现DescriptorException：应为主键字段EclipseLink定义一个非只读映射

我有以下非常简单的设计：

一个俱乐部有多支球队，每支球队都有球队类型代码（性别-年龄段代码）加上一个序号（球队），例如大于20的男性为“ MO20”，其序号代表该年龄组的第一，第二等团队。这是Teams的PK。你明白了。

俱乐部映射：

@Entity
@Table(name = "Clubs")
public class Club implements Serializable
{
    private static final long serialVersionUID = 1L;

    @Id
    @Column
    private Integer id;

    @Basic(optional = false)
    @Column
    private String name;

    @Basic(optional = false)
    @Column
    private String code;

    @OneToMany(mappedBy = "club")
    private List<Team> teams;

    ...
}

团队映射：

@Entity
@Table(name = "Teams")
public class Team implements Serializable
{
    private static final long serialVersionUID = 1L;

    @EmbeddedId
    private TeamPk embeddedId;

    @MapsId("clubId")
    @ManyToOne(optional = false,fetch = FetchType.EAGER)
    @JoinColumn(name = "club_id",insertable = false,updatable = false)
    private Club club;

    ...
}

@Embeddable
public class TeamPk implements Serializable
{
    private static final long serialVersionUID = 1L;

    @Column(name = "club_id")
    private Integer clubId;

    @Column(name = "team_type_code")
    private String teamTypeCode;

    @Column(name = "ordinal_nbr")
    private Integer ordinalNbr;

    ...
}

例外：

Caused by: Exception [EclipseLink-28019] (Eclipse Persistence Services - 2.7.7.v20200504-69f2c2b80d): org.eclipse.persistence.exceptions.EntityManagerSetupException
Exception Description: Deployment of PersistenceUnit [BBStatsPU] failed. Close all factories for this PersistenceUnit.
Internal Exception: Exception [EclipseLink-0] (Eclipse Persistence Services - 2.7.7.v20200504-69f2c2b80d): org.eclipse.persistence.exceptions.IntegrityException
Descriptor Exceptions: 
---------------------------------------------------------

Exception [EclipseLink-46] (Eclipse Persistence Services - 2.7.7.v20200504-69f2c2b80d): org.eclipse.persistence.exceptions.DescriptorException
Exception Description: There should be one non-read-only mapping defined for the primary key field [Teams.club_id].
Descriptor: RelationalDescriptor(net.bbstatstest.i265.entity.Team --> [DatabaseTable(Teams)])

Runtime Exceptions: 
---------------------------------------------------------

    at org.eclipse.persistence.exceptions.EntityManagerSetupException.deployFailed(EntityManagerSetupException.java:241)
    ... 182 more
Caused by: Exception [EclipseLink-0] (Eclipse Persistence Services - 2.7.7.v20200504-69f2c2b80d): org.eclipse.persistence.exceptions.IntegrityException
Descriptor Exceptions: 
---------------------------------------------------------

Exception [EclipseLink-46] (Eclipse Persistence Services - 2.7.7.v20200504-69f2c2b80d): org.eclipse.persistence.exceptions.DescriptorException
Exception Description: There should be one non-read-only mapping defined for the primary key field [Teams.club_id].
Descriptor: RelationalDescriptor(net.bbstatstest.i265.entity.Team --> [DatabaseTable(Teams)])

Runtime Exceptions: 
---------------------------------------------------------

    at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.initializeDescriptors(DatabaseSessionImpl.java:762)
    at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.initializeDescriptors(DatabaseSessionImpl.java:698)
    at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.initializeDescriptors(DatabaseSessionImpl.java:629)
    at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.postConnectDatasource(DatabaseSessionImpl.java:868)
    at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.loginAndDetectDatasource(DatabaseSessionImpl.java:811)
    at org.eclipse.persistence.internal.jpa.EntityManagerFactoryProvider.login(EntityManagerFactoryProvider.java:256)
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:772)
    ... 180 more

EclipseLink抱怨Teams.club_id的列映射：

There should be one non-read-only mapping defined for the primary key field [Teams.club_id].

但是为什么？

嵌入的ID字段或更确切的ID类在@Column字段上具有clubId，而没有insertable = true,updatable = true，因此它默认为可写的，至少文档是这样说的： https://javaee.github.io/javaee-spec/javadocs/javax/persistence/Column.html#insertable--

因此，所有其他club_id映射必须为insertable = true,updatable = true才能是只读的，就像Team.club关系一样。

问题：

这是怎么了？

请注意，当在insertable = ...,updatable = ...和Team.club之间切换TeamPk.clubId时，整个过程都起作用。

为什么EclipseLink在这里令人窒息？对我来说似乎是个虫子。

PS：我正在使用EclipseLink 2.7.7。 （仅添加hibernate标签以引起更多关注）

解决方法

通过将@MapsId("clubId")放在关联上，您是说'clubId不会不提供其自己的映射。相反，应使用此处对此属性的映射来映射clubId属性'。

这意味着在持久化实体时，Eclipselink将使用Team.club的ID填充club_id连接列，然后，将使用该连接列的值填充 Java属性 Team.embeddedId.clubId。 您放置在Team.embeddedId.clubId上的任何映射都将被忽略。

该错误来自Eclipselink认为club_id不被映射两次的事实。相反，仅考虑Team.club上的映射。作为主键属性的唯一映射，它可能不是insertable = false,updatable = false。

解决方案很简单：

1. 如果要Team.club控制club_id列的值，请放下insertable = false,updatable = false
2. 相反，如果您希望Team.embeddedId.clubId控制club_id，请完全放下@MapsId