Re: Mapping hierarchy in one table problem

Hi,

which version of OJB do you use?

Schmidt wrote:
> Hi,
> 
> I'm facing a hard time trying to fix a problem in my app. Consider the
> floowing class hierarchy:
> class Project {..}
> class ChildProject extends Project {..}
> class GrandChildProject extends ChildProject {..}
> 

How do you set the ojbConcreteClass attribute in your java object?

> All these classes are mapped to the same table: PROJECT_TABLE
> 
> Here are the mappings:
> 
> <class-descriptor table="PROJECT_TABLE" class="br.com.xxx.model.Project">
>     <extent-class class-ref="br.com.xxx.model.ChildProject" />
>     ...some fields here...
>     <field-descriptor name="ojbConcreteClass" column="CLASS_NAME"
> jdbc-type="VARCHAR" />
> </class-descriptor>
> 
> <class-descriptor table="PROJECT_TABLE"
> class="br.com.xxx.model.ChildProject">
>     <extent-class class-ref="br.com.xxx.model.GrandChildProject" />
>     ...some fields here...
>     <field-descriptor name="ojbConcreteClass" column="CLASS_NAME"
> jdbc-type="VARCHAR" />
> </class-descriptor>
> 
> <class-descriptor table="PROJECT_TABLE"
> class="br.com.xxx.model.GrandChildProject ">
>     ...some fields here...
>     <field-descriptor name="ojbConcreteClass" column="CLASS_NAME"
> jdbc-type="VARCHAR" />
> </class-descriptor>
> 
> Somehow when I search for GrandChildProject objects, OJB returns a
> ChildProject reference. This ends up in a ClassCastException. Is there
> anything wrong in the mappings or strategy used in this example?

The mapping seems ok.

regards,
Armin

> 
> Thanks in advance!