Hibernate version: 3.1.3
DB: Oracle 10.1.0.3.0
JDBC Driver: 10.2.0.2
Problem:
I have a many-to-many pointing to a subclass trying to load a bi-directional one-to-one via property-ref.
Mapping file, many-to-one unique
Code:
<hibernate-mapping>
<class table="T_DOCUMENT" name="Document">
<id column="ID" name="id">
<generator class="sequence">
<param name="sequence">T_Document_ID_SEQ</param>
</generator>
</id>
<many-to-one not-null="true" unique="true" column="classification_id" lazy="false" cascade="save-update" name="classification" class="DocClassification"/>
</class>
</hibernate-mapping>
(
for simplicity reasons, I only post one subclass)
Code:
<hibernate-mapping>
<class table="T_CLASSIFICATION" name="Classification">
<id column="ID" name="id">
<generator class="sequence">
<param name="sequence">T_Classification_ID_SEQ</param>
</generator>
</id>
<discriminator type="string" column="type_string"/>
<bag table="T_OBJECT_CLASSIFICATION" access="field" lazy="false" name="classificationValues">
<key column="classification_id"/>
<many-to-many column="classification_value_id" class="ClassificationValue"/>
</bag>
<subclass name="DocClassification" discriminator-value="DOCUMENT">
<one-to-one name="classifiedObject" lazy="false" property-ref="classification" class="Document"/>
</subclass>
</class>
</hibernate-mapping>
Code:
<hibernate-mapping>
<class table="T_CLASSIFICATION_VALUE" name="ClassificationValue">
<id column="ID" name="id">
<generator class="sequence">
<param name="sequence">T_Classification_Value_ID_SEQ</param>
</generator>
</id>
<bag table="T_OBJECT_CLASSIFICATION" lazy="false" inverse="true" name="classifications">
<key column="classification_value_id"/>
<many-to-many column="classification_id" class="Classification"/>
</bag>
<property name="externalIdentifier" column="customer_identifier"/>
</class>
</hibernate-mapping>
Now, when trying to load a Document, it's Classification (subclass DocClassification) and then all associated ClassificationValues, all works fine.
Going the other way does not. I load a ClassificationValue and get it's list of Classifications. The number of objects is as expected. Asking all of the loaded Classifications for their respective objects returns null in all cases.
To me, this looks like the "one-to-one property-ref" is the problem, but I can't figure out why. The mapping itself to me looks quite similar to the one given in the doc (
bidirectional one-to-one association on a foreign key), only obvious difference being the use of subclass.
I've already tried multiple changes to the mappings, e.g. not asking for the actual subclass (DocClassification) but rather the abstract base class (Classification) in the many-to-one in Document.
Changing the many-to-many on the ClassificationValue to the actual subclass (DocClassification instead of Classification) then makes it work. But that does take away the Benefit of using a subclass.
Is there anything wrong in the mapping, a problem with subclassing, etc.?
Or is there another way to map this situation?
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