I read from tomee jpa 101 page:
In some cases objects or collections of objects that become Detached may
not have all the data you need. This can be because of lazy loading. With
lazy loading, data isn't pulled from the database and into the
PersistenceContext/Cache until it is requested in code. In many cases the
Collections of persistent objects returned from an
javax.persistence.Query.getResultList() call are completely empty until you
iterate over them. A side effect of this is that if the Collection becomes
Detached before it's been fully read it will be permanently empty and of no
use and calling methods on the Detached Collection can cause strange errors
and exceptions to be thrown. If you wish to Detach a Collection of
persistent objects it is always a good idea to iterate over the Collection
at least once.
........
I think it is this the problem.
So when i do:
Into a stateless ejb
em.merge (customer);
Collection <Orders> ordersCollection =customer.getOrdersCollection ();
foreach (Orders ord: ordersCollection){
system.out.println ("Loaded Order with id=" +ord.getId ());
}
return customer;
// or return ordersCollection ????
It is correct hoe iterate for avoid collection element null ???
Il 17/nov/2016 09:47, "Romain Manni-Bucau [via TomEE & OpenEJB]" <
[email protected]> ha scritto:
> check Movies clas in
> http://tomee.apache.org/examples-trunk/injection-of-
> entitymanager/README.html
>
>
>
>
> Romain Manni-Bucau
> @rmannibucau <https://twitter.com/rmannibucau> | Blog
> <https://blog-rmannibucau.rhcloud.com> | Old Blog
> <http://rmannibucau.wordpress.com> | Github <https://github.com/
> rmannibucau> |
> LinkedIn <https://www.linkedin.com/in/rmannibucau> | JavaEE Factory
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>
> 2016-11-17 9:34 GMT+01:00 mauro2java2011 <[hidden email]
> <http:///user/SendEmail.jtp?type=node&node=4680564&i=0>>:
>
> > Dont have a example on githup repo please ?
> >
> > Il 17/nov/2016 09:17, "Romain Manni-Bucau [via TomEE & OpenEJB]" <
> > [hidden email] <http:///user/SendEmail.jtp?type=node&node=4680564&i=1>>
> ha scritto:
> >
> > > Hello Mauro
> > >
> > > Personally i try to ensure i eagerly featch these relationships with a
> > > jpql
> > > query when possible. If really not possible using a @Stateful bean
> with
> > an
> > > EXTENDED persistence context can help.
> > >
> > > Le 17 nov. 2016 07:46, "mauro2java2011" <[hidden email]
> > > <http:///user/SendEmail.jtp?type=node&node=4680562&i=0>> a écrit :
> > >
> > > > i am a user of tomee 1.7.2 plus .and 1.7.4 plus and 7.0.2 plus .
> > > >
> > > > I have tried to generate a crud web app.
> > > >
> > > > Into my domain model i have for example a entity Customer with
> > > @OneToMany
> > > > Collection<Order> collectionOrders.
> > > >
> > > > And a Entity Order with @ManyToOne Customer customer.
> > > >
> > > > I would use the default lazy fetch type for orderscollection into
> > > Customer
> > > > entity.
> > > >
> > > >
> > > > From a view jsf page i show the list of customer inside a table
> > > >
> > > > When i click on the row , with ajax i set the selected customer into
> > the
> > > > viewScoped customerController .
> > > >
> > > >
> > > > So into the customerController i call a EJBFacede and i reattach the
> > > > custoemer to em and retrive
> > > > the orderslist.. with :
> > > > inside the EJB:
> > > >
> > > >
> > > > public Customer reattachandLoadORdersCOllection(Customer
> > > > customToReattach){
> > > > Customer attached=em.merge(customToReattach).
> > > >
> > > > Collcetion<Orders> collection= atrtached.getOrdersCollection();
> > > >
> > > > collection.size();
> > > > customToReattach.setOrdersCOllection(collection):
> > > > return customToReattach
> > > > }
> > > > i set the collection to to customer and i return it to
> controller.
> > > >
> > > > Into the controller i take the Customer returned from the ejb with
> > > > ordersColletion and i set to field Customer selected.
> > > >
> > > >
> > > >
> > > > so i you ask please :
> > > > On tomee or some github repo it is present a working solution from
> a
> > > Tomee
> > > > plus that uses OpenJPA and CDI and has AJAX elements where they
> need
> > to
> > > > access LAZY relationships.?
> > > >
> > > > OR that show how resolve the lazy loading
> > > >
> > > > I would understand like resolve the lazi loading with tomee openjpa
> > > >
> > > > tank you in advance.
> > > > Mauro
> > > >
> > > >
> > > >
> > > > --
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