Hi Tim,
It seems like you would want to do the following within the same
RequestFactory service method (and probably the same JPA transaction, as
well):
Persist the new Phone entity
Persist the new Person entity
Is that possible?
/dmc
On Thu, Feb 24, 2011 at 12:27 AM, Tim <tim.muri...@gmail.com> wrote:
> Hello all,
>
> I'm using GWT 2.2 and I'm trying to wrap my head around a problem that
> seems fundamental to the combination of RequestFactory, JPA and sub-
> entity creation.
>
> I have a Person entity with a @OneToMany list of Phone entity. In
> client code, I use the editor framework to present data to the user.
> If I want to create a new Phone entity for my Person, I use the
> RequestContext to create a Phone proxy and attach it to the Person
> proxy directly and send only the Person proxy to the server (since it
> includes the new Phone proxy). On the server side, I have a method
> that guarantees persist()ing the Phone entity before merge()ing the
> Person entity to avoid problems with JPA.
>
> The problem is, the server code handling this request needs to enforce
> some security requirements. This involves executing a query with the
> shared EntityManager (since GWT requires a single EntityManager per
> request). If the query is a named query or a native query, the
> EntityManager will flush before returning the result of the query.
> Because GWT has already fetched the existing Person entity from the
> database and added a new, not yet persisted Phone entity to the
> Person, JPA fails with: "During synchronization a new object was found
> through a relationship that was not marked cascade PERSIST:
> Phone{id=null}."
>
> I don't see any way to avoid this problem. RequestFactory is creating
> the Person entity that my handler code is given. So far the only
> solution I see is using multiple EntityManagers, one for read-write
> operations, one for read-only. With that approach I run my named
> queries on the read-only manager avoiding a flush on GWT-dedicated
> EntityManager. I really don't like this idea, and since this seems
> like a common enough setup, I'm hoping someone has encountered and
> solved this problem.
>
> Any ideas?
>
> -Tim
>
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