Hello,
I have had a similar problem but not using JSF. I was using a home
grown MVC application. The problem I experienced was doing a request
using a specific URI. The URI was like so "webapp/somePage.jsp". I
was able to fix it by changing it to "/webapp/somePage.jsp". The
first time you can get to that page just fine. But any subsequent
time you could not. I don't know if these are two entirely different
problems that cause the same effect or what.
The next question I would ask is, on a refresh or clicking the href a
second time are you able to step through your servlet filter again?
Was there something in request scope on the first click but when you
do a refresh or the href click, that something is no longer there?
You are dying on the JSF page you were forward too; so I bet you are
getting to the filter.
Calvin Hill
return Programmer.someType()
On Dec 27, 2006, at 7:36 AM, yuvalgo wrote:
Hi,
Im trying to take control of the navigation.
let me explain:
I wish to have my own piece of code to parse the request URI and
control the
navigation to the next JSF page.
This functionality is desired for accomplishing a permalinks scheme
of some
sort.
For example
The link root/yuval/yuvals_stuff should cause the following to happen:
- I parse the request with a servlet filter and know that we need
to load
some data for yuval.
- I use a ViewHandler to load the data (it delegates the call to some
service that gets the data from the database)
- I now forward the user to a known jsf page that is bounded with the
viehandler and presents yuval's stuff .
Actually, the first time i try to use the code, the navigation goes
well.
But right after refresh or calling the same url again I get an
exception.
The code and the exception are provided here:
Here is what i do inside a servlet filter (I also tried to put this
code
inside the faces servlet, just for testing):
<code>
FacesContext fc = FacesUtils.getFacesContext(req, res);
String action = "#{viewPollViewHandler.go2}";
javax.faces.application.Application application = fc.getApplication();
MethodBinding mb =
application.createMethodBinding("#{viewPollViewHandler.go2}",null);
String outcome = (String)mb.invoke(fc, null);
String fromAction = mb.getExpressionString();
NavigationHandler navigationHandler =
application.getNavigationHandler();
navigationHandler.handleNavigation(fc, fromAction, outcome);
String viewId = fc.getViewRoot().getViewId();
UIViewRoot view = fc.getApplication().getViewHandler().createView(fc,
viewId);
view.setViewId(viewId);
fc.setViewRoot(view);
fc.getExternalContext().dispatch(viewId);
fc.responseComplete();
</code>
Explanation:
First we try to get the FacesContext, using the current request and
response
objects. Now we know what action we want to invoke on what
ViewHandler, so
we go ahead and make a method binding for this method through the JSF
Application context. Now we invoke the method and get the outcome
String
from it. Till now everything seems to work ok – we get the
ViewHandler's
method invoked correctly and we get the proper outcome String from it.
This means the ViewHandler is now populated with our needed data,
so all we
have left to do is go to the presentation page that uses this
ViewHandler.
We use JSF's NavigationHandler to navigate as usual, giving it a
"fromAction" and an outcome. Now we want the name of the page for this
navigation, so we get the view id from the FacesContext. The view
id is
correct and points to the next page as states in the faces-
navigation.xml,
so we set it as the new view root and try to "dispatch()" (which is
the same
as "forward()") to it.
The result seems sufficient, as we get to the next page and all the
data is
presented correctly (sometimes, in IE only we experienced some
javascript
errors that were unknown). The big problem occurs when trying to hit
"REFRESH" or clicking back and then trying the original href link
again. We
suddenly get a NullPointerException that occurred in the "getValue
()" method
of JSF's getValueBinding()".
Can anyone contribute?
Thank in advance!
Yuval.
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