[eclipselink-users] Fetch Groups

["Mathias Walter" <mathias.walter@xxxxxxx>]

Hi,

is there any example how to implement FetchGroupTracker?

The EclipseLink Wiki explains how to set the fetch groups, but not how to
implement FetchGroupTracker.
Unfortunately, FetchGroupTracker must be implemented for all entities
participating in a fetch group. And also a DescriptorCustomizer seems to be
necessary for each of these entities which instantiates a new
FetchGroupManager. That's a bit ugly in my opinion but could be easily
implemented and copy & paste in persistence.xml. Or is there an easier way?

If the FetchGroupManager is not instantiated a QueryException with error
6114 is thrown:

"You must define a fetch group manager at descriptor <entity> in order to
set a fetch group on the query <query>."

Is there a full example how to use fetch groups?

I also tried EclipseLink 2.0, but got the same errors. My main goal is to
use Nested Fetch Groups as explained at
http://wiki.eclipse.org/EclipseLink/Development/JPA/NestedFetchGroups and
bug 244124.

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Kind regards,
Mathias