JPA如何制作复合主键的复合外键部分 [英] JPA how to make composite Foreign Key part of composite Primary Key

问题描述

我有下列表格，我如何将它们映射到JPA实体：

I have following tables how can i map them to JPA entities:

TABLE Event {
EventID
SourceID
....Other event fields
PK (EventID, SourceID)
}

TABLE MEETING {
MeetingID
EventID
SourceID
...Other meeting fields
PK(MeetingID,EventID, SourceID)
FK(EventID, SourceID) //FK with Event table
}

Event表与会议表具有一对多的关系。如何在JPA中映射这种双向关系？

The Event table has one-to-many relationship with Meeting table. How can i map this bi-directional relationship in JPA?

推荐答案

@Embeddable
public class EventID {
    public int eventID;
    public int sourceID;
}

@Entity
public class Event {
    @EmbeddedId
    public EventID id;

    @OneToMany(mappedBy="event")
    public Collection<Meeting> meetings;
}

@Embeddable
public class MeetingID {
    public EventID eventID; // corresponds to ID type of Event
    public int meetingID;
}

@Entity
public class Meeting {
    @EmbeddedId
    public MeetingID id;

    @MapsId("eventID")
    @JoinColumns({
        @JoinColumn(name="EventID", referencedColumnName="EventID"),
        @JoinColumn(name="SourceID", referencedColumnName="SourceID")
    })
    @ManyToOne
    public Event event;
}

在JPA 2.1规范中讨论，2.4.1。

Discussed in JPA 2.1 spec, section 2.4.1.

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