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From Pinaki Poddar <ppod...@apache.org>
Subject Re: noob: understanding dynamic fetch modes
Date Wed, 30 Sep 2009 03:27:23 GMT

> ojem.getFetchPlan().addField(A.class, "B");

Mike is right.


Michael Dick wrote:
> 
> Hi Chris,
> I'm not an expert on FetchPlans / FetchGroups, but it sounds like example
> 5.22 from [1] is what you're trying to do..
> 
> [1]
> http://openjpa.apache.org/builds/latest/docs/manual/manual.html#ref_guide_fetch_single_field
> 
> 
> So your code would look like this :
> 
> OpenJPAEntityManager ojem = OpenJPAPersistence.cast(em);
> ojem.getFetchPlan().addField(A.class, "B");
> // run query as normal.
> 
> You'd have to reset the fetchPlan afterwards
> (getFetchPlan().removeField(A.class, "B") should work). Alternatively you
> could use the @FetchGroup annotation and specify that on your query.
> 
> There may be other paths to achieve your goal, but these are what I would
> try first.
> 
> Hope this helps,
> 
> -mike
> 
> On Tue, Sep 29, 2009 at 11:02 AM, Christopher Giblin
> <CGI@zurich.ibm.com>wrote:
> 
>>
>> Hi,
>> I have a class, "A", with a one-to-many relationship to another class,
>> "B".
>> Thus A refers to a collection of B.
>> Normally I want to load the collection lazy and therefore set fetch to
>> "LAZY" in my orm.xml. In one case, however, I want to load A eagerly.
>>
>> I thought the following would do the trick :
>>
>>  Query query = em.createQuery("select m from ...");
>>  OpenJPAQuery jpaQ = OpenJPAPersistence.cast(query);
>>  JDBCFetchPlan fetchPlan = (JDBCFetchPlan) jpaQ.getFetchPlan();
>>  fetchPlan.setEagerFetchMode(FetchMode.PARALLEL);
>>  List<Identity> results = query.getResultList();
>>
>> but in the debugger, I see the collection is loaded lazily.
>>
>> I also tried using the property instead :
>>
>>  query.setHint("openjpa.FetchPlan.EagerFetchMode","parallel");
>>
>>
>> But this resulted in a IllegalArugmentException.
>>
>> What am I missing?
>>
>> Thanks,chris
>>
>>
> 
> 


-----
Pinaki 
-- 
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