Re: [eclipselink-users] Join with additional Where condition

["Joe Mc." <m_joe_c@xxxxxxxxxxx>]

Thanks J.Sutherland,
I will try the DescriptorCustomizer!



James Sutherland wrote:
> 
> So you want your OneToMany to include the regionCode in the query to
> filter the courses.  JPA only allows relationships to be on foreign keys
> (JoinColumns), so does not support this.  EclipseLink does however, you
> can use a DescriptorCustomizer to customize the mapping.  You can use
> EclipseLink Expressions to set the OneToManyMapping's selectionCriteria to
> an Expression that include the foreign key and the filter.
> 
> Ideally EclipseLink would have annotation/xml support for doing this, so
> feel free to log a bug for that.
> 
> You could also just filter the result in your object model, as you seem to
> be doing.
> 
> 
> Joe Mc. wrote:
>> 
>> Hi together,
>> 
>> I have the following use case with a fictive example:
>> - ManyToMany relation
>> - Table User(id, name, city, ...)
>> - Table Course(id, name, regionCode, ...)
>> - Some courses are only for special regions (> 0, if regionCode = 0 is
>> the course everywhere available)
>> - FetchType.Eager
>> - configuration through annotations
>> 
>> So, the select on User delivers all the users, with all the corresponding
>> Courses. However, only the courses with the regionCode = 0 are wanted.
>> Question:
>> How is it possible to add additional where condition for the Joins? The
>> wanted additional condition is
>> c.regionCode = 0
>> 
>> The following query is unfortunately not successful
>> entityManager.createQuery("SELECT u FROM User u, Course c 
>>                                        WHERE c.regionCode = 0 AND ((u.id
>> = 1) OR (u.id = 2) OR ...)");
>> 
>> EclipseLink modifies the Query with the Outer-Joins and the conditon
>> "c.regionCode = 0" does not fit any more (result is not as excepted)
>> 
>> My current solution is:
>> - Use @PostLoad to remove the Courses from the User.courses property,
>> which have course.regionCode != 0. But that is not really nice!
>> 
>> How is it possible to constrain the resulting set, ideally with the
>> annotations.
>> 
>> Thanks in advance!
>> 
>> Best Regards
>> 
>> Mc.Joe
>> 
>> 
>>  
>> 
> 
> 

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