James Moores wrote:
Hi,
I know that it's probably a bit early to be looking for ADF Faces help
here in light of the fact that it's only just joined MyFaces, but I'm
getting no joy at all on the Oracle forums and people on this list have
been so helpful that I thought it was worth a try:
I use the ADF Faces 'Process scope' facility a great deal.
Unfortunately I have a significant problem. My backing beans cannot be
initialized from the faces-config because their values come from a
database. I therefore use a separate backing bean to populate the
values (because the beans are reused by different pages). The problem
is that this initialization bean isn't naturally referenced on the page,
and so it's never created by the framework and the initialization
doesn't happen. I've gotten around this by putting in a dummy reference
to the bean, that triggers my initialization code either in the
constructor or in a dummy 'get' method e.g.:
<af:outputText value="initializingBean.init">
... rest of jsp page...
This works fine except that now if I change anything in the process
scope during the execution of either the constructor or the get method
on my 'initializingBean' then it's added nicely (confirmed by printing
out the Map). The problem is by the time an action method (or
actionListener) is called, the new values in the Map have dissapeared
and the state of the map is reset back to what it was before the call to
initializingBean.
Looking at the source code for ProcessScopeMap
(adf-faces/adf-faces-impl/src/main/java/oracle/adfinternal/view/faces/co
ntext/ProcessScopeMap.java) I found a rather worrying comment:
// =-=AEW This strategy assumes that the ProcessScopeMap
// will be inherited from a prior request, have things
// added and removed prior to Render Response *without
// the token being requested*, then have the token used
// repeatedly during Render Response *without further
// mutations*. Both of these assumptions seem very
// dubious!
Now I'm not sure if theis has anything to do with my problem, but it
looks a bit suspect. Unfortunately I don't know enough about the
internals of either MyFaces or ADF Faces to *fix* the problem.
There seems to be very little documentation about processScope's and
many postings on the Oracle forum on the subject have gone unanswered.
I know it's an experimental feature, but it's a pretty important one!
I've been banging my head against a brick wall with this one for nearly
a week now so any light anyone can shed on this or ideas of how I could
better do my initialization later in the phase cycle (which I think is
the problem) would be greatly appreciated.
Based on the comment, it would seem that your problem is that you need
to do your initialization *earlier* in the phase cycle -- i.e. before
the Render Response phase begins.
Shale's View Controller feature [1] provides a great solution to this;
the init() and prerender() hooks would be the two options you'd want to
consider for doing your initialization.
If you don't want to use Shale, you could implement the same approach in
your own app with a little bit more work. Basically, you'd implement
your own phase listener and call your initialization logic in
beforePhase(). I don't have a sample code snip to hand, but it's fairly
straightforward.
L.
[1] http://struts.apache.org/struts-shale/features-view-controller.html
