On Wed, 18 Mar 2015 07:21:06 -0300, Poggenpohl, Daniel
<daniel.poggenp...@isst.fraunhofer.de> wrote:
Hello again,
Hi!
I need a session storage where I store the currently logged on user.
Reading about it in the documentation, they recommend using
@SessionState because my user is a complex object, also containing lists
of other entities.
You need to use @SessionState because @Persist is only valid for a given
page or component. Page1's @Persist private User user; is stored in a
different session attribute than Page2's @Persist private User user;. If
you want something persisted across pages, you need to use @SessionState.
Being a complex object makes no difference about choosing one annotation
or the other.
My user also is an entity in a database. So, when a user logs in, the
appropriate entity is retrieved from the database, an "AppSession"
object is created containing, among e.g. the time of login, the user
object. Is this the right way to do it? Or should I only store the ID in
the session?
This is extremely dependent on how you're going to use your user
information. If you're going to show their name in every page, for
example, and you store just the id, you'll be querying the database for
the same information every request (unless you use some kind of cache
between your page or component or mixin and your database).
Now when the SessionState object is created, it can be used in any other
page or component using the same SessionState annotation and the same
type. Does it need to be the same name
I'd say it doesn't, as I've not read otherwise.
@SessionState is keyed by type, not by field name, so @SessionState
private User user; and @SessionState private User currentUser; will point
to the same object, stored in the same session attribute.
To do this, a service receives the user. The service tries to access the
lazy collection, but fails with a
"failed to lazily initialize a collection of role:".
What I gather from this is, services don't operate within transactions?
The error isn't related to transactions nor Tapestry at all. It's related
to your Hibernate/JPA usage: one entity is loaded in one request, one
Hibernate session/JPA entity manager instance. Then, in another request,
another session/entity manager instance, you try to load some lazy field.
You need to use the merge() method of org.hibernate.Session or
EntityManager to reattach the entity to the current Hibernate session or
JPA entity manager.
Services operate within transactions as long as you use @CommitAfter
(tapestry-hibernate or tapestry-jpa) or something like that (other
library).
--
Thiago H. de Paula Figueiredo
Tapestry, Java and Hibernate consultant and developer
http://machina.com.br
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