Hello,
I'm working for about 6 months with Hibernate but I'm a newbie in creating topics in this forum. It's the first time now I do not find the right answers for my problems here, so I have to ask for it:
In my mappings I implemented table-per-subclass inheritance, but in case of my physical datamodel I was not able to implement the inheritance on a shared primary-key. So my base-class table "TerminalOwner" has foreign-key columns for each different type of "TerminalOwner". For example one foreign-key column to a "Merchant" and also one to an "Office" which are all build up in different tables.
In my case only one of these foreign-keys can be set in the "TerminalOwner" table. I know that this is a very bad model, but this model exists for years now and it would cost too much time and so money to change that (also other applications are working with this physical datamodel). It also was not implemented by me.
Hibernate version: 3.2 cr1
Mapping documents:
TerminalOwner
Code:
<hibernate-mapping>
<class name="com.efkon.tac.mappings.TerminalOwner" table="MT_TERMINALOWNER">
<id name="pkMtTerminalowner" type="long">
<column name="PK_MT_TERMINALOWNER" precision="16" scale="0" />
<generator class="assigned" />
</id>
<discriminator column="OWNERTYPE"/>
<property name="pkMdMerchant" type="java.lang.Long">
<column name="PK_MD_MERCHANT" precision="16" scale="0" />
</property>
...
</class>
</hibernate-mapping
Code:
<hibernate-mapping>
<subclass name="com.efkon.tac.test.Merchant" extends="com.efkon.tac.mappings.TerminalOwner" discriminator-value="M">
<join table="MD_MERCHANT">
<key column="PK_MD_MERCHANT" property-ref="pkMdMerchant"/>
<property name="name" type="string">
<column name="NAME" length="64" />
</property>
</join>
</subclass>
</hibernate-mapping>
Oracle 10g
The generated SQL (show_sql=true):Code:
select
terminalow0_.PK_MT_TERMINALOWNER as PK1_35_,
terminalow0_1_.NAME as NAME44_,
terminalow0.OWNERTYPE as clazz_
from
MT_TERMINALOWNER terminalow0_,
MD_MERCHANT terminalow0_1_
where
terminalow0_.PK_MT_TERMINALOWNER=terminalow0_1_.PK_MD_MERCHANT(+)
instead of
terminalow0_.PK_MT_TERMINALOWNER=terminalow0_1_.PK_MD_MERCHANT(+) this it should be:
terminalow0_.PK_MD_MERCHAND=terminalow0_1_.PK_MD_MERCHANT(+)because table TERMINAL_OWNER includes foreign-key columns for each ownertype. In this example I only showed ownertype "Merchant".
I tested these mappings with Hibernate-Tools 3.2 beta7. Also the sql-output is from there.
I also tried it with:
Code:
<join table="MD_MERCHANT">
<key column="PK_MD_MERCHANT" property-ref="pkMdMerchant" foreign-key="PK_MD_MERCHANT"/>
and
Code:
<join table="MD_MERCHANT">
<key column="PK_MD_MERCHANT" foreign-key="PK_MD_MERCHANT"/>
as it is valid for the "join" element. But in every case hibernate generated the following wrong sql-query:
terminalow0_.PK_MT_TERMINALOWNER=terminalow0_1_.PK_MD_MERCHANT(+)
In my case I also have to implement this via inheritance instead of one-to-one mappings, because the logical datamodel is defined in this way.
So does anyone know if it is possible to map on a foreign-key of the parant-class instead of a shared primary-key?
Thanks in advance,
Thomas
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