Hibernate @EmbeddedId + join

Question

I have a hibernate mapping problem. I have the following two DB tables (I am not allowed to change the DB):

LOCATIONS {
   ID, -- PK
   NAME
}

LOCATION_GROUP         


        

Answer 1

The location must be mapped with @JoinColumn, and not with @Column:

@JoinColumn(name = "LOC_ID")
public Location getLoc() {
    return loc;
}

Note that this is not standard JPA though. To make it standard, you would use

Embeddable Class

@Embeddable
public class LocationGroupId implements Serializable {

    private static final long serialVersionUID = -6437671620548733621 L;
    private Long locationId;
    private String group;

    @Column(name = "LOC_ID")
    public Long getLocationId() {
        return loc;
    }

    @Column(name = "GROUP_NAME")
    public String getGroup() {
        return group;
    }
    // ...
}

EmbeddedId Used

@Entity
@Table(name = "LOCATION_GROUPS")
public class LocationGroup {

    private LocationGroupId id;
    private Location location;

    @EmbeddedId
    public LocationGroupId getId() {
        return id;
    }

    @ManyToOne
    @JoinColumn(name = "LOC_ID")
    @MapsId("locationId")
    private Location getLocation() {
        return location;
    }
    // ...
}

These two mappings are explained in the documentation.