The database I have to work with has defined primary keys on virtually every table, but ideally I would like to implement some inheritance at the object layer. e.g. The database defines an asset with a primary key, a contract which is an asset has it's own primary key and a clientContract which is an contract has it's own primary key.

Asset
assetId(PK)

Contract
contractId(PK)
assetId - join key

ClientContract
clientContractId(PK)
contractId - join key

I can create an inheritance mapping via a subclass(join) in V3.0 on assetId and that all works. Unfortunately I cannot then subclass ClientContract, a class gets created but no values are populated, I assume this is because contractId is not available for the join. Is there anyway round this or would I need to get the data model changed.

Thanks,

John

Attached is the mapping file.

If I run the query - from asset as a where a.assetId = 21 I get returned a ClientContract but none of the client contract details are populated. The contract details and asset details are present and the contractNumber is set as 1012
If I run the query - from ClientContract as cc where cc.contractNumber= 1012 I get nothing found.


<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">


<hibernate-mapping package="com.inmezzo.titan">

<class name="Asset" table="asset">
<id name="assetId" column="asset_id" type="java.lang.Integer">
<generator class="native" />
</id>

<discriminator column="case_of_asset_type_id" formula="case_of_asset_type_id"/>

<!-- Mapping for AssetReferenceCode association. -->
<set name="referenceCodes" cascade="none" lazy="true" inverse="true">
<key>
<column name="for_asset_id" not-null="true" />
</key>
<one-to-many class="AssetReferenceCode" />
</set>

<subclass name="Contract" discriminator-value="8">

<join table="contract">
<key column="is_asset_id"></key>
<property name="contractNumber" column="contract_number"
type="java.lang.String" not-null="true" />

<property name="contractId" column="contract_id" type="java.lang.Integer" not-null="true" />

</join>

<subclass name="ClientContract" discriminator-value="12">


<!-- Mapping for ContractServiceFee association. -->
<set name="contractServiceFees"
cascade="none"
lazy="true"
inverse="true">
<key>
<column name="for_client_contract_id" not-null="true"/>
</key>
<one-to-many class="ContractServiceFee"/>
</set>

<join table="client_contract">
<key column="is_contract_id"></key>
<property name="commencementDate" column="commencement_date" type="java.util.Date" />
<property name="greenSortingIndicator" column="green_sorting_indicator" type="java.lang.String" />
<property name="contractSetupFee" column="contract_setup_fee" type="java.lang.Double" />
<property name="clientContractId" column="client_contract_id" type="java.lang.Integer" />

</join>

</subclass>
</subclass>


<subclass name="PhysicalAsset">

<!-- Mapping for AssetFeatureValue association. -->
<set name="assetFeatureValues" cascade="none" lazy="true"
inverse="true">
<key>
<column name="of_physical_asset_id" not-null="true" />
</key>
<one-to-many class="AssetFeatureValue" />
</set>

<join table="physical_asset" >
<key column="is_asset_id"></key>
<!--
<property name="physicalAssetNumber" column="physical_asset_number" type="java.lang.String" not-null="true" />
-->
<property name="physicalAssetNumber"
column="physical_asset_number" type="java.lang.String"
not-null="true">
<meta attribute="finder-method">findByName</meta>
</property>

<many-to-one name="modelSpecification"
column="of_model_specification_id" class="ModelSpecification" />

<many-to-one name="assetSpecification"
column="case_of_asset_specification_id" class="AssetSpecification" />

<many-to-one name="equipmentType"
column="case_of_equipment_type_id" class="EquipmentType" />

<!--
<many-to-one name="asset" column="is_asset_id" class="Asset" not-null="true" />
-->

</join>

<subclass name="EquipmentItem" discriminator-value="1">
</subclass>
<subclass name="Bundle" discriminator-value="2"></subclass>
<subclass name="Parcel" discriminator-value="3">
<!-- Mapping for CollectionRequest association. -->
<set name="collectionRequest" cascade="none" lazy="true"
inverse="true">
<key>
<column name="for_asset_id" not-null="true" />
</key>
<one-to-many class="CollectionRequest" />
</set>
</subclass>
<subclass name="Pallet" discriminator-value="4"></subclass>
<subclass name="Transfer" discriminator-value="5">
</subclass>
<subclass name="RCYPallet" discriminator-value="6">
</subclass>
<subclass name="Container" discriminator-value="7">
</subclass>
<subclass name="Item" discriminator-value="9"></subclass>
<subclass name="PWO" discriminator-value="10"></subclass>
<subclass name="Picklist" discriminator-value="11">
</subclass>
</subclass>

</class>

</hibernate-mapping>

I think I'm starting to understand this. A lot of the issues I am seeing seem to be because the subclasses have different identifiers to the parent. Even the one-to-many mappings are failing. Is there a way of specifying a different identifier for the subclass or must it always be the same identifier as the parent?