Problem with polymorphic collections

neierl · **Joined:** Tue Feb 08, 2005 6:16 am **Posts:** 6

Hibernate version: hibernate-3.2
Annotation version: hibernate-annotations-3.2.0.CR2

Hi,

I'm trying now for days to solve my problem, which I'm not sure if it is a problem or expected behaviour, since it seems nobody else has this problem.

My problem is as follows:

I have an object called BillingUnit which contains many different types of costs. All costs inherit from the same base class. I use single-table inheritance with a descriminator.

When I call a cost method from BillingUnit to get a specific cost, I get all the costs and not just the correct cost type. It seems that in the SQL the descriminator does not get evaluated or is ignored, which makes me think that there is something wrong with my mapping!

Here is the data model, respectively the mappings. For simplicity only the relavent fields are included.

Code:

@Entity()
@Table(name = "AE")
public class BillingUnit implements DomainModel {
   private Integer _id;

   private Set<HeatingWarmwaterCostTree> _heatingWarmwaterCostTrees;

   @Id
   @Column(name = "AE_IDPK", nullable = false)
   public Integer getId() {
      return _id;
   }

   @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
   @JoinColumn(name = "KOST_DAID")
   public Set<HeatingWarmwaterCostTree> getHeatingWarmwaterCostTrees() {
      return _heatingWarmwaterCostTrees;
   }

   public void setHeatingWarmwaterCostTrees(Set<HeatingWarmwaterCostTree> heatingWarmwaterCostTrees) {
      _heatingWarmwaterCostTrees = heatingWarmwaterCostTrees;
   }

   }

Code:

@Entity
@Table(name = "KOSTEN")
@Inheritance(strategy= InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="KOST_HZWWORHNK", discriminatorType=DiscriminatorType.INTEGER)
public class CostTree implements DomainModel {
   private Integer _id;

   public CostTree() {
   }

   @Id
   @Column(name = "KOST_IDPK")
   public Integer getId() {
      return _id;
   }

   public void setId(Integer id) {
      _id = id;
   }
}

Code:

@Entity
@DiscriminatorValue(value = "0")
public class HeatingWarmwaterCostTree extends CostTree {
   public HeatingWarmwaterCostTree() {
   }
}

I'm using Spring for Session management

Code:

   
public BillingUnit find(int id) throws DaoException {
      try {
         return (BillingUnit) getHibernateTemplate().load(BillingUnit.class, id);
      } catch (DataAccessException e) {
         throw new DaoException(e, LOG);
      }
   }

UnitTest

Code:

   public void testBillingUnit() throws Exception {
      BillingUnitService billingUnitService = getBean("billingUnitService");

      BillingUnit billingUnit = billingUnitService.getBillingUnit(2499);
      assertNotNull(billingUnit);

      for (HeatingWarmwaterCostTree heatingWarmwaterCostTree : billingUnit.getHeatingWarmwaterCostTrees()) {
         System.err.println(heatingWarmwaterCostTree.getDescription());
      }
   }

When I run the test it prints all the different costs which are associated with this billingunit, but actually there is only one HeatingWarmWaterCost in the DB.

Any help would be appreciated!

neierl · **Joined:** Tue Feb 08, 2005 6:16 am **Posts:** 6

The only solution I found to this problem is using the @Where annotation

Code:

@Where(clause="discriminator_column_name='discriminator_value'")

as described in http://forum.hibernate.org/viewtopic.php?t=961213

Is this the correct way to do this?

What I was also wondering is that the @Method annotation comes from package 'org.hibernate.annotations', which is hibernate specific!

Luo · **Joined:** Thu Oct 26, 2006 5:44 am **Posts:** 4

We have the same problem with:

Hibernate Core 3.2.1 GA
Hibernate Annotations 3.2.0 GA
Hibernate EntityManager 3.2.0 GA

Any comments from Hibernate support team? Is this a bug? Thanks.

emmanuel · **Posted:** Thu Dec 07, 2006 1:17 pm

nope, not a bug.
If you want specific association per subtype you need a specific join column for each.

Luo · **Joined:** Thu Oct 26, 2006 5:44 am **Posts:** 4

emmanuel wrote:

nope, not a bug.
If you want specific association per subtype you need a specific join column for each.

Thank you for your reply, Emmanuel.

However I have a different opinion. From a view of native Hibernate this may be not a bug, but from a view of JPA this must be a bug. Anyway, TopLink Essentials can handle this properly, without any code or db modification in our application. Our persistence code is strictly at the level of JPA.

emmanuel · **Posted:** Sun Dec 17, 2006 4:42 pm

this is an implementation side effect