Comments inline...
On 11/16/06, Wonseok Kim <guruwons_at_gmail.com> wrote:
>
> Hi all,
> There is an interesting but not clear issue which Sahoo brought up.
>
> For example, there are entities which have Joined inheritance strategy.
>
> @Entity @Inheritance(strategy=JOINED)
> public class SuperClass {
> @Id @Column(name="ID") String id;
> }
>
> @Entity @PrimaryKeyJoinColumn(name="PK", referencedColumnName="ID")
> public class SubClass extends SuperClass {...}
>
> And if other entity references the Subclass like below,
>
> @Entity
> public class User {
> ...
> @JoinColumn(name="USER_ID", referencedColumnName="???")
> SubClass subClass;
> }
>
> What should be the referencedColumnName value? Should it be the primary
> column of SubClass table or SuperClass?
> You can see below Sahoo's message.
>
> What do you think?
My original understanding of the spec has been that referencedColumnName
always refers to the column of the target entity's table.
So "PK" (the primary key column of the SubClass) is, I think, right one.
Spec: 9.1.6 JoinColumn Annotation says
...If the referencedColumnName element is missing, the foreign key is
assumed to refer to the primary key of the referenced table.
Table 8 in p.170 says
referencedColumnName: (Optional) The name of the column referenced this
foreign key column. When used with mappings, the column is in the table of
the target entity.
There is no mention about inheritance, but my interpretation is that the
column of the target table should be used.
Is there more clear idea?
Thanks,
-Wonseok
On 16 Nov 2006 03:01:10 -0000, ss141213_at_dev.java.net <ss141213_at_dev.java.net>
> wrote:
> >
> > https://glassfish.dev.java.net/issues/show_bug.cgi?id=1153
> >
> > ------- Additional comments from ss141213_at_dev.java.net Thu Nov 16
> > 03:01:09 +0000 2006 -------
> > Hi Wonseok,
> >
> > Although Table B has ID1 and ID2 as primary key columns and those two
> > columns
> > are also foreign keys to A.ID1 and A.ID2, but the IDs for the derived
> > entity B
> > should still be mapped to A.ID1 and A.ID2. That's my understanding. In
> > the
> > example below(thanks to Sherry Shen who brought this use case to my
> > attention)
> > where the columns in derived classes have been renamed to PK1 and PK2
> > respectively, should the referencedColumnNames in @JoinTable be using
> > PK1 and
> > PK2 or ID1 and ID2? I think, they should be using ID1 and ID2 as shown
> > below.
> >
> > @Embeddable class Person {
> > String id1;
> > String id2;
> > }
> >
> > @Entity
> > @Inheritance(strategy=JOINED)
> > class Person {
> > @EmbeddedId PersonPK personPK;
> > ...
> > }
> >
> > @Entity
> > @PrimaryKeyJoinColumns({
> > @PrimaryKeyJoinColumn(name="PK1", referencedColumnName="ID1"),
> > @PrimaryKeyJoinColumn(name="PK2", referencedColumnName="ID2")
> > })
> > public class NaturalPerson {
> > @ManyToMany(cascade=CascadeType.ALL)
> > @JoinTable(name="PARENT_CHILDREN",
> > joinColumns={
> > @JoinColumn(name="P_ID1", referencedColumnName="ID1"),
> > @JoinColumn(name="P_ID2", referencedColumnName="ID2")
> > },
> > inverseJoinColumns={
> > @JoinColumn(name="C_ID1", referencedColumnName="ID1"),
> > @JoinColumn(name="C_ID2", referencedColumnName="ID2")
> > }
> > )
> > List<NaturalPerson> children;
> > }
> >
> > With the current fix in place, this does not work. It works when we use
> > PK1 and
> > PK2 as the referenced column names in @JoinTable.
> >
> > Thanks,
> > Sahoo
> >
>
>