Re: [eclipselink-users] @JoinColumn: Using a function in "name" or "refe

[James Sutherland <jamesssss@xxxxxxxxx>]

JPA only allows basic fields/foreign keys in JoinColumns.  You can do this in
EclipseLink using a DescriptorCustomizer.  Get the mapping from the
descriptor and set its selectionCriteria using an EclipseLink Expression. 
The Expression can use the function or any other complex criteria.


Zarar Siddiqi wrote:
> 
> Hello,
> 
> I've come across a situation where I need to use a DB2 function inside
> @JoinColumn attributes.  I want to have something like this:
> 
>    @OneToMany @JoinColumns({
>            @JoinColumn(name="PERSON_ID", referencedColumnName =
> "PERSON_ID"),
>            @JoinColumn(name="PERSON_TYPE", referencedColumnName = "*
> SUBSTR(PERSON_TYPE,1,5)*")
>    })
> 
> However, I get the following exception message when I do this since
> SUBSTR(PERSON_TYPE,1,5) isn't really a column.  If I put PERSON_TYPE,
> everything works fine but it's incorrect business logic.
> 
> *When the source entity class uses a composite primary key, a @JoinColumn
> must be specified for each join column using the @JoinColumns. Both the
> name
> and the referenceColumnName elements must be specified in each such
> @JoinColumn.*
> 
> I understand that this isn't exactly how most composite key relationship
> are
> modeled but I'm working with a legacy system.  Any ideas for a workaround?
> I really don't want to use a native query.
> 
> Thanks
> 
> 


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