key-many-to-one annotation issue

fortknox · **Joined:** Sun Nov 16, 2003 3:04 pm **Posts:** 24

Hibernate version:
3.2.0GA

I've found a funny issue while using hibernate3 with ejb3.

I have a wierd table structure:
LegacyTable - old table in our DB with a composite key
LegacyExtendedTable - new table that is a child of the Legacy Table with an extra field
NewTable - a new, and simple table (one Id field that is generated by hibernate)
ManyToManyTable - between LegacyExtendedTable and NewTable with an extra field, so I have to write it out in hibernate as a new class.

I was able to get everything working without issue until working on the many-to-many table. Its using a key of two many-to-ones to two tables. One being a simple Id, the other a composite key.

Initially I used the following (I had to genericise the code, so my apologizes for minor syntax issues)

Code:

@Table(name = "manyToManyTable")
public class ManyToManyTable
{
   private int extraField;
   private ManyToManyTablePk pk;

  @Column(name="whatever") public int getExtraField(){return extraField;}
  @Id ManyToManyTablePk pk;
}

@Embeddable
public class ManyToManyTablePk
{
   private LegacyExtendedTable legacy;
   private NewTable new;

    @ManyToOne
    @JoinColumns({
        @JoinColumn(name = "PK_NO"), @JoinColumn(name = "PK_NO_2"),
        @JoinColumn(name = "PK_INT")})
   public LegacyExtendedTable getLegacy() { return legacy; }

    @ManyToOne
    @JoinColumn(name = "NEW_ID")
   public NewTable getNew() { return new; }
}

On deploy, Hibernate complained that the NewTable FK was bad because the NewTable code didn't have all four FK constraints. I figured this was because hibernate mapped the annotation like a many-to-one instead of a key-many-to-one. I replaced the code with the following

Code:

@Table(name = "manyToManyTable")
@IdClass(ManyToManyTablePk.class)
public class ManyToManyTable
{
   private int extraField;
   private LegacyExtendedTable legacy;
   private NewTable new;

  @Column(name="whatever") public int getExtraField(){return extraField;}

    @Id
    @ManyToOne
    @JoinColumns({
        @JoinColumn(name = "PK_NO"), @JoinColumn(name = "PK_NO_2"),
        @JoinColumn(name = "PK_INT")})
   public LegacyExtendedTable getLegacy() { return legacy; }

    @Id
    @ManyToOne
    @JoinColumn(name = "NEW_ID")
   public NewTable getNew() { return new; }
}

@Embeddable
public class ManyToManyTablePk
{
   private LegacyExtendedTable legacy;
   private NewTable new;

   public LegacyExtendedTable getLegacy() { return legacy; }

   public NewTable getNew() { return new; }
}

And the code worked, fine.

It looks like key-many-to-one only works when you put an @Id tag before the @ManyToOne. If the @ManyToOne is embedded in a PK class, and you don't use the @IdClass method in your object, it doesn't recognize it as a key-many-to-one.

Is anyone else noticing this? I don't want to mark it up as a bug unless someone else sees a similar situation.

Thanks!

emmanuel · **Posted:** Thu Dec 07, 2006 1:41 pm

Weird, I have testcase for both in org.hibernate.test.annotations.idmanytoone

fortknox · **Joined:** Sun Nov 16, 2003 3:04 pm **Posts:** 24

Do both examples use composite pks for the many-to-ones?

I have to wait to get home to d/l the source and test cases, but anon browsing I glanced and it looks like storecustomer uses @IdClass with a non annotatied PK class, but Card uses @Id that isn't composite (although I'm not with the html browser, and just glanced at it). I'll get back to you later tonight or tomorrow night when I've had a chance to check out the test case.

Thanks for the response!