4 Replies Latest reply on May 27, 2013 2:57 AM by hamzabenmansour

ClassCastException when using Flash scope and Ajax

hamzabenmansour May 24, 2013 8:33 AM

Hi,

I have a JSF 2.0 portlet running on eXo Platform 3.5 and JBoss EAP 5 using portletBridge 3.1.2.Final. I defined an error page for my portlet which may display the exception message. When an error occur, a custom ExceptionHandler extracts the message, puts it in the flash scope and redirects to the error page after calling the NavigationHandler (with a redirect).

I have one complex page comprised of different forms submitted with a4j:commandLink components. when I submit one form and an unexpected Exception occurs, the error page is not diplayed and I have in the logs

javax.faces.FacesException: javax.faces.FacesException: .....

.....

Caused by: java.lang.ClassCastException: org.jboss.portletbridge.context.flash.FlashHttpServletAdapter cannot be cast to javax.portlet.PortletResponse

at org.jboss.portletbridge.context.PortletExternalContextImpl.getPortletResponse(PortletExternalContextImpl.java:186)

at org.jboss.portletbridge.context.PortletExternalContextImpl.getNamespace(PortletExternalContextImpl.java:195)

at org.jboss.portletbridge.context.AbstractExternalContext.encodeNamespace(AbstractExternalContext.java:152)

at javax.faces.context.ExternalContextWrapper.encodeNamespace(ExternalContextWrapper.java:115)

at javax.portlet.faces.component.PortletNamingContainerUIViewRoot.setId(PortletNamingContainerUIViewRoot.java:59)

at javax.faces.component.UIViewRoot.<init>(UIViewRoot.java:211)

at javax.portlet.faces.component.PortletNamingContainerUIViewRoot.<init>(PortletNamingContainerUIViewRoot.java:47)

at sun.reflect.GeneratedConstructorAccessor529.newInstance(Unknown Source)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:532)

at java.lang.Class.newInstance0(Class.java:372)

at java.lang.Class.newInstance(Class.java:325)

at com.sun.faces.application.ApplicationImpl.newThing(ApplicationImpl.java:1727)

When, debugging, the implementation of the externalContext used is the ResourceRequestExternalContextImpl (due to the AJAX request) where we cast the response, which is in our case a FlashHttpServletAdapter to a PortletResponse.

The work around in my case was to simply remove the use of the flash scope.

Is this scope supported ? Or am I misusing the API ?

Thanks a lot for your help

1. Re: ClassCastException when using Flash scope and Ajax

kenfinni May 24, 2013 10:58 AM (in response to hamzabenmansour)

It's a little difficult to tell from the above what the problem might actually be.

Can you include the code where set the information into the flash scope and then how you retrieve it?

Thanks
Ken
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2. Re: ClassCastException when using Flash scope and Ajax

hamzabenmansour May 24, 2013 11:37 AM (in response to kenfinni)

Hi Ken,

The code used in my ExceptionHandlerWrapper implementation is :

try {
ELFlash.getFlash().put("exceptionMessage", throwable.getMessage());
throwable.printStackTrace(pw);
ELFlash.getFlash().put("exceptionTrace", sw.toString());
ELFlash.getFlash().put("afficherErreur", Boolean.valueOf(afficherException));
nav.handleNavigation(fc, null, "/error?faces-redirect=true");
fc.renderResponse();
} finally {
iterator.remove();
}

and in my error.xhtml :

....
<h:outputText value="#{flash.exceptionTrace}" rendered="#{flash.afficherErreur == true}"/>
 
....

Thanks for your reply.

Regards

3. Re: ClassCastException when using Flash scope and Ajax

kenfinni May 24, 2013 1:13 PM (in response to hamzabenmansour)

Hamza,

It looks like you're retrieving it through EL ok, but instead of calling ELFlash.getFlash(), you're better of getting the Flash with:

FacesContext.getCurrentInstance().getExternalContext().getFlash().

as then it's more portable.

It's also possible that you're hitting this bug, which would mean needing to upgrade to PBR 3.2.0.Final to resolve it.

Ken
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4. Re: ClassCastException when using Flash scope and Ajax

hamzabenmansour May 27, 2013 2:57 AM (in response to kenfinni)

Hi Ken,

Thank you for your helpfull answer. I'll try you suggestions.

Regards
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