Hibernate 3.0.5 & 3.1rc2

Mapping

<class name="ProductDefinition">
...
<set name="contractProducts" inverse="true">
<key column="pde_id"/>
<one-to-many class="ContractProduct"/>
</set>

<set name="specialProducts" inverse="true">
<key column="pde_id"/>
<one-to-many class="SpecialProduct"/>
</set>
</class>

// Hierarchy to single table mapping:
<class name="ProductComponent">
...
<discriminator column="class" type="java.lang.String" length="2"/>

<subclass name="ContractProduct" discriminator-value="CP">
<many-to-one name="productDefinition"
class="ProductDefinition"
column="pde_id"/>
</subclass>

<subclass name="SpecialProduct" discriminator-value="SP">
<many-to-one name="productDefinition"
class="com.tpgmail.spp.model.ProductDefinition"
column="pde_id"/>
</subclass>
</class>

If I retrieve ProductDefinition.contractProducts & ProductDefinition.specialProducts I get a WrongClassException because hibernate does not use the discriminator value retrieving these collections.

The result of this is that both collection retrieval queries return all rows that map to the given parent and there is no discrimination for the correct type.

Are there any workarounds?

These are the generated OneToManyLoader statements:

14:43:10:621 DEBUG (OneToManyLoader.java:106) Static select for one-to-many com.tpgmail.spp.model.ProductDefinition.specialProducts: select specialpro0_.pde_id as pde12_1_, specialpro0_.id as id1_, specialpro0_.id as id0_, specialpro0_.tcn as tcn19_0_, specialpro0_.last_change as last4_19_0_, specialpro0_.last_group_change as last5_19_0_, specialpro0_.dov_id as dov6_19_0_, specialpro0_.pco_id as pco7_19_0_, specialpro0_.sequence as sequence19_0_, specialpro0_.number_of_outlets as number10_19_0_, specialpro0_.pde_id as pde12_19_0_ from spp_product_component specialpro0_ where specialpro0_.pde_id=?
14:43:10:591 DEBUG (OneToManyLoader.java:106) Static select for one-to-many com.tpgmail.spp.model.ProductDefinition.contractProducts: select contractpr0_.pde_id as pde12_1_, contractpr0_.id as id1_, contractpr0_.id as id0_, contractpr0_.tcn as tcn19_0_, contractpr0_.last_change as last4_19_0_, contractpr0_.last_group_change as last5_19_0_, contractpr0_.dov_id as dov6_19_0_, contractpr0_.pco_id as pco7_19_0_, contractpr0_.sequence as sequence19_0_, contractpr0_.number_of_outlets as number10_19_0_, contractpr0_.pde_id as pde12_19_0_, contractpr0_.con_id as con13_19_0_ from spp_product_component contractpr0_ where contractpr0_.pde_id=?

You haven't put a discriminator-value on your ProductComponent class. When I had this problem (which admittedly was back with Hibernate 2.1) I added an unused value on my "base" class so that it never got created (something like 'discriminator-value="XX"') and that fixed it.

I don't know if that's the official fix, but it worked for me.

Hi,

Thanx for the suggestion, unfortunately it does not make a difference for hibernate3. I added the discriminator value to the baseclass but the generated sql is still the same and I still get the exception.

I got it working using the force attribute for discriminator
There is some information about this option in the documentation but it does not refer to this specific situation.

There's still a problem when using discriminator force="true". The subclass colelctions get read correctly but when you remove all objects from the collection of one subclass, Hibernate deletes all objects of *all* subclasses and not just the subclass in question.

In your example if you want to remove all "contractProducts" associated with a ProductDefinition, you clear the contractProducts set and when you try to save the parent ProductDefinition object, Hibernate deletes all specialProducts too.


The query it executes would look like :
delete from spp_product_component contractpr0_ where contractpr0_.pde_id=?

I hope this issue gets fixed.

Sanjiv