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From "Patrick Linskey" <>
Subject RE: possible to write a JPA Query to that filters both an Entity and its relationship entities?
Date Fri, 23 Feb 2007 22:06:56 GMT
You could do that, but personally, I tend to be wary of putting computed
data into the entity types themselves. You're in the grey area in the
question of when to use your domain model as a DTO graph vs. creating a
separate set of DTOs.


Patrick Linskey
BEA Systems, Inc. 

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> -----Original Message-----
> From: Tom Mutdosch [] 
> Sent: Friday, February 23, 2007 1:58 PM
> To:
> Subject: Re: possible to write a JPA Query to that filters 
> both an Entity and its relationship entities?
> Hi Patrick,
> Thanks for the query suggestion.  I guess what I was 
> initially thinking 
> of doing was incorrect in that JPA doesn't really give me a "view" of 
> what I want.  That is, I can never get a Department object 
> containing a 
> list of filtered Employees.  A JPA object returned from a query is 
> always going to be an exact representation of the database.  So your 
> Department object is always going to contain all of the 
> Employees in its 
> relationship.
> So like you mentioned, I can still get all the information using one 
> query, and then just process those results as I want them.  I imagine 
> that this would entail some sort of wrapper bean that would house the 
> Department and the filtered list of Employees.  Or what if I added a 
> regular method to my Department entity called 
> getFilterEmployees() which 
> would return a List that I populated with the filtered 
> results from my 
> query?  Does that seem like a reasonable thing to do -- if I 
> didn't want 
> to deal with a wrapper object but still have all of my desired data 
> captured by a single Entity? 
> Thanks
> Tom
> Patrick Linskey wrote:
> > It is, but it doesn't buy you much in this situation -- the 
> oldTimers
> > collection in your example won't be filtered to just the 
> ones that are
> > old. It'll be all the employees in the dept.
> >
> > -Patrick
> >
> >   

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