Hi,

I'm quite new to hibernate, I was using toplink a lot. and now I'm trying to upgrade our project to Hibernate. I read the doc, and H in Action.

most of the mapping is easy to convert but this one gives me many problems...


I have the following inherintence.

Person (abstract) -> LegalPerson (abstract) - Organization
- Manufacturer
- Dealer

also Person has a reference to one legalPerson.
it's not self reference. as it happends on the person level.

I have tables for each entity (Person, LegalPerson, Org, Man.., Dealer..)
in the Person table there is a foreign key to the LegalPerson table
Person has a column named (legalperson_id)

when a use session load to get for example a manufacturer it works perfectly if there is no legalperson attached to the entity but if it has one. it throws an exception ->
Cannot instantiate abstract class or interface: at.oeamtc.edds.model.LegalPerson

it's obvious as the LegalPerson is abstract. and hibernate shold use the same mechnism to find out what kind of contrete class to instanciate that it's using when just load the class itself.

can someone point me to some direction how I shold change my mapping to get the desired result...



Hibernate version:
2.1.7
Mapping documents:

<class name="at.oeamtc.edds.model.Person" table="Person" polymorphism="implicit">
<id name="id" type="long" column="id">
<generator class="sequence">
<param name="sequence">seq_person</param>
</generator>
</id>
<property name="name" column="name" type="string"/>
<many-to-one name="country" column="country_id" foreign-key="fk_person_country_id" class="at.oeamtc.edds.model.Country" cascade="none"/>
<many-to-one name="legalPerson" column="legalperson_id" foreign-key="fk_person_legalperson_id" cascade="save-update"/>
<joined-subclass name="at.oeamtc.edds.model.LegalPerson" table="legalPerson" extends="at.oeamtc.edds.model.Person">
<key column="id"/>
<property name="defaultPwd" column="defaultpwd" type="string"/>
<property name="url" column="url" type="string"/>
<property name="image" column="image" type="string"/>
<property name="toYourHands" column="toyourhands" type="string"/>
<many-to-one name="address" column="address_id" foreign-key="fk_legalperson_address_id" class="at.oeamtc.edds.model.Address" cascade="all" unique="true"/>
<joined-subclass name="at.oeamtc.edds.model.Manufacturer" table="manufacturer">
<key column="id"/>
<many-to-one name="organization" column="organisation_id" foreign-key="fk_manufacturer_org_id" class="at.oeamtc.edds.model.Organization" cascade="none"/>
</joined-subclass>
<joined-subclass name="at.oeamtc.edds.model.Organization" table="org">
<key column="id"/>
</joined-subclass>
</joined-subclass>
</class>


Name and version of the database you are using:
Oracle 9i

You should be mapping the sublcasses with the <joined-subclass> tag. Since you have a table-per-subclass, you won't need to use the <subclass> and a discriminator column. Check the documentation:

http://www.hibernate.org/hib_docs/refer ... nheritance