Are you using Spring? I didn't have much luck using the OSIV filter
without also using Spring's HibernateDaoSupport (hibernateTemplate).
I've thought about trying something like the DataSqueezer approach, but
I can't see that as a complete solution. Maybe the way I use Tapestry
is unusual, but I like to drop my DAO objects directly into my Tapestry
pages, let Tapestry update the object properties as necessary, and then
explicitly save the object in my Tapestry page code. For example, if I
need to edit a certain Cat, I can do this:
Cat cat = getCatService().findByName("tom");
setCat (cat); // Tapestry page property
html:
<input jwcid="@TextField" value="ognl:cat.Color"/>
<input jwcid="submitContinue"/>
java:
// after necessary validations, etc.
cat.save();
I think the DataSqueezer approach would work best if you fetched a Cat,
copied each Cat property to individual page properties (ie - setColor(
cat.getColor()), modified those properties, used the DataSqueezer method
to re-fetch the original Cat, then performed explicit updates such as
cat.setColor(getColor()), and then cat.save(). For me, this would only
be useful maybe 20% of the time.
Shawn
Quoting Andreas Andreou <[EMAIL PROTECTED]>:
> Shawn Church wrote:
>
> >The problem with this is that it does not address the issue of
> >reattaching detached objects to the currently-open session. Since
> it is
> >natural in Tapestry to instantiate an object, use it in a page, and
> then
> >to persist the (potentially) changed object, the object must first
> be
> >reattached to the Hibernate session. Even if the object is not
> >persisted, if it contains lazy collection references it is necessary
> to
> >reattach the object in order for the collection to be properly
> initialized.
> >
> >
> 100% correct. That's why I'm also re-attaching those objects, though
> not
> using a HibernateService, but explicit DAO calls.
> Perhaps the 'best' solution is the one using custom DataSqueezers
>
http://wiki.apache.org/jakarta-tapestry/FrequentlyAskedQuestions/SpringHibernate
> but i have yet to try it...
>
> >The only reliable solution I have found is to use Spring's
> >OpenSessionInView filter with singleSession=true, and then to
> explicitly
> >reattach objects in pageBeginRender(). I use a custom
> HibernateService
> >class which implements methods for attach(), evict(), and merge().
> The
> >attach() method actually does a getSession().lock(object,
> >LockMode.NONE), but it handles NonUniqueObjectExceptions which will
> >commonly be thrown when using lazy collections if one of the
> collection
> >objects happens to already exist in the session.
> >
> >Shawn
> >
> >Quoting Andreas Andreou <[EMAIL PROTECTED]>:
> >
> >
> >
> >>Regarding to not using servlet filters for the OpenSessionInView
> >>approach, I can confirm that other approaches work!
> >>First of all,
> >>i've always used the HibernateUtil class posted in hibernate
> forums
> >>(and maybe also included in Hibernate in Action) that stores and
> >>gets
> >>session and transaction objects in thread local variables.
> >>
> >>So, opening a hibernate session is never a problem (whichever
> method
> >>first uses one, creates it) and so it only remains the issue of
> >>closing it
> >>somewhere.
> >>
> >>I haven't tried the cleanupAfterRequest() of Engine approach.
> >>Instead i've always extended the
> >>pageEndRender(PageEvent event)
> >>in a BasePage (that all my pages extend) and there I just do:
> >>
> >> super.pageEndRender(event);
> >> HibernateUtil.closeSession();
> >>
> >>The nice thing is that this closeSession() never complains, no
> >>matter
> >>if no session is found, or if it has already been closed.
> >>
> >>Anyway, I can post the HibernateUtil class here if you want to...
> >>Andreas
> >>
> >>Alejandro Scandroli wrote:
> >>
> >>
> >>
> >>>Henry Chen wrote:
> >>>
> >>>
> >>>
> >>>
> >>>>I have been searching around desperately for solution of
> handling
> >>>>lazy-loading database objects in tapestry. I configured
> >>>>OpenSessionInViewFilter for Tapestry pages. It worked for some
> >>>>
> >>>>
> >>cases
> >>
> >>
> >>>>but not all. For example, in the table component, the first page
> >>>>
> >>>>
> >>was
> >>
> >>
> >>>>good, but when I selected other pages, it gave me the
> >>>>LazyInitialization exception - owning session was closed. Is
> there
> >>>>
> >>>>
> >>any
> >>
> >>
> >>>>way around it now? Thanks a lot!
> >>>>
> >>>>
> >>>>
> >>>>
> >>>Hi , I'm having the same problem on Trails.
> >>>This quote may help.
> >>>
> >>>quote form Open Session in View discussion on Hibernate site.
> >>><quote>
> >>>Open Session pattern and Tapestry web framework
> >>>24 Mar 2004, 19:27 wassup
> >>>
> >>>If you develop your application with Tapestry framework it is
> >>>
> >>>
> >>better
> >>
> >>
> >>>do not use Servlet Filters to manage request cycle. More
> preferable
> >>>
> >>>
> >>to
> >>
> >>
> >>>override setupForRequest() and cleanupAfterRequest() of Engine
> >>>class.
> >>></quote>
> >>>
> >>>I have no time to try this.
> >>>Please let me know if it works for you, or if you find another
> >>>
> >>>
> >>workaround.
> >>
> >>
> >>>Saludos.
> >>>Alejandro.
> >>>
> >>>PD:- please, excuse my English.
> >>>
> >>>
> >>>
> >>>---------------------------------------------------------------------
> >>>To unsubscribe, e-mail:
> >>>
> >>>
> >>[EMAIL PROTECTED]
> >>
> >>
> >>>For additional commands, e-mail:
> >>>
> >>>
> >>[EMAIL PROTECTED]
> >>
> >>
> >>>
> >>>
> >>>
> >>>
> >>---------------------------------------------------------------------
> >>To unsubscribe, e-mail:
> [EMAIL PROTECTED]
> >>For additional commands, e-mail:
> >>[EMAIL PROTECTED]
> >>
> >>
> >>
> >
> >
> >
> >
> >---------------------------------------------------------------------
> >To unsubscribe, e-mail:
> [EMAIL PROTECTED]
> >For additional commands, e-mail:
> [EMAIL PROTECTED]
> >
> >
> >
> >
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: [EMAIL PROTECTED]
> For additional commands, e-mail:
> [EMAIL PROTECTED]
>
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
