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From "Evgeny Shepelyuk" <>
Subject Re: Lazy load for detached entities
Date Wed, 12 Sep 2007 09:04:25 GMT
>> The idea is that Toplink JPA supports that feature. OpenJPA - no.
>> Maybe this can be done as some configurable behaviour ?
> They do, but really, all that they are doing is hiding the open EM. In
> other words, the objects are not actually really detached yet.
> What type of application are you building? Most server frameworks
> these days have some sort of request boundary concept, such as a
> ServletFilter; given such a concept, it's trivial to register an EM
> with a ThreadLocal or some equivalent construct at the beginning of
> the request, and close the EM when the context closes.

It's not web application but rather some core service processing request
coming into it by RMI, REST/HTTP and even SOAP :)

Now we're in the middle of migration to JPA from custom ORM layer.
And just wanna separate "business logic" classes from JPA stuff completely.
We can easily avoid loading of field of detached entites writing smth like  

OrderEntity order = .... ;// passed detached entity from some DAO
UserEntity user = new UserDAO().get(order.getUserId());

but i think more convenient way will be following :)

OrderEntity order = .... ;// passed detached entity from some DAO
UserEntity user = order.getUser();

Problem is that for example i have one class that makes some DB operation  
and it's used from
several internal clients. Those clients are asking for some entity, then  
ask for it's dependants etc.
And i'm kinda unwilling to inject EntityManager into those top-level  

Best Regards
Evgeny K. Shepelyuk

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