[hibernate-issues] [Hibernate-JIRA] Updated: (HHH-1015) Incorrect SQL generated when one-to-many foreign key is in a discriminated subclass table

[Krasimir Chobantonov (JIRA)]

     [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1015?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Krasimir Chobantonov updated HHH-1015:
--------------------------------------

    Attachment: hhh-1015.patch

Attaching a patch that fixes the problem - the patch is against Hibernate core version 3.3.1.GA.

Note that  because hibernate does not keep the reverse property to the OneToMany relationships when using HBM (e.g. key element does have only the column information)  then the path relies only on the column name information to get to the reverse property and to check if it is mapped to a join table (e.g. using SecondaryTable annotation)

Also the code is only modified so that the described case in the issue is going to work and also fixes the problem with the Hibernate schema validation. Probably there may be some other places that needs to be fixed as well (this needs to be validated byt the respective components' owners)


> Incorrect SQL generated when one-to-many foreign key is in a discriminated subclass table
> -----------------------------------------------------------------------------------------
>
>                 Key: HHH-1015
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1015
>             Project: Hibernate Core
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.1 beta 2
>         Environment: Hibernate versions 3.1 beta 3 and 3.0.5
>            Reporter: Steven Grimm
>            Priority: Minor
>         Attachments: hhh-1015.patch
>
>
> I have the following mappings describing a hierarchy of events and a class that the events refer to:
> <hibernate-mapping package="com.xyz">
>     <class name="Event" table="event" discriminator-value="-1">
>         <id name="Id" type="long" column="event_id"/>
>         <discriminator column="event_type_id" type="integer" />
>         <subclass name="EventPayer" discriminator-value="-3">
>             <join table="event_payer">
>                 <key column="event_id" />
>                 <many-to-one name="payer" column="payer_id" class="Payer" />
>             </join>
>             <subclass name="EventPayerCreated" discriminator-value="1" />
>         </subclass>
>     </class>
>     <class name="Payer" table="payer">
>         <id name="payerId" column="payer_id" type="java.lang.Long"/>
>         <set name="eventPayers" inverse="true" cascade="save-update">
>             <key column="payer_id"/>
>             <one-to-many class="EventPayer"/>
>         </set>
>     </class>
> </hibernate-mapping>
> When I fetch the Payer.eventPayers collection, Hibernate generates this SQL:
> select eventpayer0_.payer_id as payer7_1_,
>     eventpayer0_.event_id as event1_1_,
>     eventpayer0_.event_id as event1_5_0_,
>     eventpayer0_1_.payer_id as payer2_6_0_,
>     eventpayer0_.event_type_id as event2_5_0_
> from event eventpayer0_
> inner join event_payer eventpayer0_1_
>     on eventpayer0_.event_id=eventpayer0_1_.event_id
> where eventpayer0_.payer_id=?
> The problem is that there is no event.payer_id column; payer_id is in the child table, not the parent. It appears that specifying a discriminated subclass in <one-to-many> is the same as specifying the superclass, or that Hibernate is ignoring the subclass's <join> element. As far as I can tell, this leaves no way to resolve bidirectional associations where one end of the association is in a discriminated subclass, which seems like a perfectly reasonable thing to want to do.
> I also tried changing <key column="payer_id"/> to <key property-ref="payer"/> in the Payer class's <set> element, but got similar behavior in the form of a "property not found" error: Hibernate is either looking in the superclass's properties rather than the subclass's or is ignoring the list of properties in the <join> element.

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