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From David Blevins <david.blev...@visi.com>
Subject Re: Fetching a Persistence Context
Date Fri, 16 Oct 2009 02:20:23 GMT
I'm not sure if I understand the overall goal.

Is this a case where the code that intends to use the  
PeristenceContext (EntityManager) does not know the name of the  
persistence unit and therefore cannot look it up or have it injected?

If so, it still should be possible to create a component that has an  
@PersistenceContext reference to the unit and then can pass it  
directly or indirectly to this more generic "work with any  
EntityManager" code.  Perhaps with a Singleton pattern like this one http://bit.ly/vklEb

You could also do a more generic version like this:  http://bit.ly/10AsNt


Hope that helps!


-David


On Oct 15, 2009, at 4:03 PM, Quintin Beukes wrote:

> Basically I need a way to progammatically retrieve a unit manager.
> Information regarding the PU is supplied to a module manager in an
> core module which has no knowledge of the module until it's notified
> of it.
>
> So, from your last e-mail, I assume it would then be possible to
> annotate the persistence context in the Startup singleton of the
> module, and then specify the class and field name to the module
> manager, which would then use this information to construct a lookup
> backwards, and then have it wrapped in a transaction (since the call
> to the module manager is a business method invocation) - unless I
> misunderstood the code.
>
> Though... 10 seconds ago I also thought of an option of doing a JNDI
> lookup of the Singleton itself and then invoke on this reference -
> this should wrap it in a transaction, which I can then use to pass in
> an injected EntityManager reference?
>
> Quintin Beukes
>
>
>
> On Fri, Oct 16, 2009 at 12:29 AM, Quintin Beukes <quintin@skywalk.co.za 
> > wrote:
>> OK. So just to confirm that things are still the same.
>>
>> I know that unit names need not be unique, so I assume you still
>> generate the unique ID suffix. How does OpenEJB then decide what to  
>> do
>> with it. I tried looking around the code, but am a bit lost on where
>> it injects these entity managers and how it decides which persistence
>> unit to use. Could you perhaps tell me where to find this?
>>
>> Quintin Beukes
>>
>>
>>
>> On Thu, Oct 15, 2009 at 5:33 PM, Jean-Louis MONTEIRO
>> <jean-louis.monteiro@atosorigin.com> wrote:
>>>
>>> Hi Quintin,
>>>
>>> you can use JNDI to get a reference.
>>> Have a look here
>>> http://www.nabble.com/Lookup-EntityManager-from-Stateless-EJB-Session-Bean-td24708299.html#a24737449
>>> http://www.nabble.com/Lookup-EntityManager-from-Stateless-EJB-Session-Bean-td24708299.html#a24737449
>>>
>>> Hope it helps.
>>> Jean-Louis
>>>
>>>
>>> Q Beukes wrote:
>>>>
>>>> Hey,
>>>>
>>>> When I have an EntityManager injected while having multiple
>>>> persistence units, I do it by specifying the unit name, something
>>>> like:
>>>> @PersistenceContext(unitName="Some-PU")
>>>> private EntityManager em;
>>>>
>>>> Is it possible to do this not by injection, but fetching it by name
>>>> through an API of some sort?
>>>>
>>>> Quintin Beukes
>>>>
>>>>
>>>
>>> --
>>> View this message in context: http://www.nabble.com/Fetching-a-Persistence-Context-tp25910491p25910759.html
>>> Sent from the OpenEJB User mailing list archive at Nabble.com.
>>>
>>>
>>
>


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