On 2/22/06, Laurie Harper <
[EMAIL PROTECTED]> wrote:
Michel Goldstein wrote:
> Hi,
>
> I have a very basic use case in which I need to access an external service
> on a getter. However, this access might fail and cause an exception. When
> the exception happens, I would like to redirect the user to an error page
> that would explain that the service is unavailable and do not allow the user
> to access that functionality until the service comes back up (so I can't
> really just add to a message and render the message using the <h:message>
> tag).
>
> My first approach was in the lines of:
>
> public TreeNode getData() {
> log.debug("Called getData");
> try {
> return resource.getDataAsTreeNode();
> } catch (Exception e) {
> log.error ("Cannot access resource!");
> getUserMessages().addMessage("Cannot access a required resource.
> Your access will be limited until the resource is available again.");
> FacesContext ctx = FacesContext.getCurrentInstance();
> ctx.getApplication
> ().getNavigationHandler().handleNavigation(ctx,"","error");
> return null;
> }
> }
>
> However, the problem is that the getter is being called twice during the
> page processing and on the second time it throws an exception claiming that
> the state is invalid during redirect. By the way, the error page navigation
> rule in faces-config.xml uses the <redirect/> directive mostly to change the
> URL on the browser so that the user can see that it is an error page.
>
> My question then is a little bit more basic than this: what it looks like to
> me is that I'm using the wrong pattern here to deal with exceptions. What
> should be the right pattern?
Add ctx.renderResponse() at the end of your exception handling code.
That'll tell JSF to jump straight to rendering the response when the
current phase ends. I think that'll do the trick.
L.
>
> Thank you,
> Michel
>
> Just for completeness sake, here is the stack trace of the error:
>
> 2006-02-22 13:01:10,485 44493 ERROR [TP-Processor3] [/ptd].[jsp] -
> Servlet.service() for servlet jsp threw exception
> javax.faces.el.EvaluationException: Cannot get value for _expression_ '#{
> test.data}'
> at org.apache.myfaces.el.ValueBindingImpl.getValue (
> ValueBindingImpl.java:402)
> at org.apache.myfaces.custom.tree2.UITreeData.getValue(
> UITreeData.java:264)
> at org.apache.myfaces.custom.tree2.HtmlTreeRenderer.encodeChildren(
> HtmlTreeRenderer.java:173)
> at javax.faces.component.UIComponentBase.encodeChildren(
> UIComponentBase.java:527)
> at javax.faces.webapp.UIComponentTag.encodeChildren(
> UIComponentTag.java :474)
> at javax.faces.webapp.UIComponentTag.doEndTag(UIComponentTag.java
> :361)
> at org.apache.jsp.exportViewResults_jsp._jspx_meth_t_tree2_0(
> org.apache.jsp.exportViewResults_jsp:381 )
> at org.apache.jsp.exportViewResults_jsp._jspx_meth_f_view_0(
> org.apache.jsp.exportViewResults_jsp:176)
> at org.apache.jsp.exportViewResults_jsp._jspService(
> org.apache.jsp.exportViewResults_jsp:100 )
> at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java
> :97)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
> at org.apache.jasper.servlet.JspServletWrapper.service (
> JspServletWrapper.java:322)
> at org.apache.jasper.servlet.JspServlet.serviceJspFile(
> JspServlet.java:291)
> at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
> at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(
> ApplicationFilterChain.java:252)
> at org.apache.catalina.core.ApplicationFilterChain.doFilter(
> ApplicationFilterChain.java:173)
> at org.apache.catalina.core.ApplicationDispatcher.invoke(
> ApplicationDispatcher.java:672)
> at org.apache.catalina.core.ApplicationDispatcher.processRequest(
> ApplicationDispatcher.java:463)
> at org.apache.catalina.core.ApplicationDispatcher.doForward(
> ApplicationDispatcher.java:398)
> at org.apache.catalina.core.ApplicationDispatcher.forward(
> ApplicationDispatcher.java:301)
> at
> org.apache.myfaces.context.servlet.ServletExternalContextImpl.dispatch(
> ServletExternalContextImpl.java :416)
> at org.apache.myfaces.application.jsp.JspViewHandlerImpl.renderView(
> JspViewHandlerImpl.java:234)
> at org.jenia.faces.template.handler.ViewHandler.renderView(
> ViewHandler.java :74)
> at org.apache.myfaces.lifecycle.LifecycleImpl.render(
> LifecycleImpl.java:372)
> at javax.faces.webapp.FacesServlet.service(FacesServlet.java:109)
> at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter (
> ApplicationFilterChain.java:252)
> at org.apache.catalina.core.ApplicationFilterChain.doFilter(
> ApplicationFilterChain.java:173)
> at org.apache.myfaces.component.html.util.ExtensionsFilter.doFilter (
> ExtensionsFilter.java:129)
> at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(
> ApplicationFilterChain.java:202)
> at org.apache.catalina.core.ApplicationFilterChain.doFilter (
> ApplicationFilterChain.java:173)
> at org.apache.catalina.core.StandardWrapperValve.invoke(
> StandardWrapperValve.java:213)
> at org.apache.catalina.core.StandardContextValve.invoke (
> StandardContextValve.java:178)
> at org.apache.catalina.core.StandardHostValve.invoke(
> StandardHostValve.java:126)
> at org.apache.catalina.valves.ErrorReportValve.invoke(
> ErrorReportValve.java:105)
> at org.apache.catalina.core.StandardEngineValve.invoke(
> StandardEngineValve.java:107)
> at org.apache.catalina.connector.CoyoteAdapter.service(
> CoyoteAdapter.java:148)
> at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java
> :307)
> at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java
> :385)
> at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:748)
> at org.apache.jk.common.ChannelSocket.processConnection(
> ChannelSocket.java:678)
> at org.apache.jk.common.SocketConnection.runIt (ChannelSocket.java
> :871)
> at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(
> ThreadPool.java:684)
> at java.lang.Thread.run(Thread.java:534)
> Caused by: javax.faces.el.EvaluationException: Exception getting value of
> property data of base of type : test.TestBean
> at org.apache.myfaces.el.PropertyResolverImpl.getValue(
> PropertyResolverImpl.java :96)
> at org.apache.myfaces.el.ELParserHelper$MyPropertySuffix.evaluate(
> ELParserHelper.java:532)
> at org.apache.commons.el.ComplexValue.evaluate(ComplexValue.java
> :145)
> at org.apache.myfaces.el.ValueBindingImpl.getValue(
> ValueBindingImpl.java:383)
> ... 43 more
> Caused by: javax.faces.el.EvaluationException: Bean: test.TestBean,
> property: data
> at org.apache.myfaces.el.PropertyResolverImpl.getProperty(
> PropertyResolverImpl.java:435)
> at org.apache.myfaces.el.PropertyResolverImpl.getValue(
> PropertyResolverImpl.java:82)
> ... 46 more
> Caused by: java.lang.reflect.InvocationTargetException
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at sun.reflect.NativeMethodAccessorImpl.invoke(
> NativeMethodAccessorImpl.java :39)
> at sun.reflect.DelegatingMethodAccessorImpl.invoke(
> DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:324)
> at org.apache.myfaces.el.PropertyResolverImpl.getProperty (
> PropertyResolverImpl.java:431)
> ... 47 more
> Caused by: java.lang.IllegalStateException
> at org.apache.catalina.connector.ResponseFacade.sendRedirect(
> ResponseFacade.java :423)
> at javax.servlet.http.HttpServletResponseWrapper.sendRedirect(
> HttpServletResponseWrapper.java:125)
> at
> org.apache.myfaces.context.servlet.ServletExternalContextImpl.redirect (
> ServletExternalContextImpl.java:490)
> at
> org.apache.myfaces.application.NavigationHandlerImpl.handleNavigation(
> NavigationHandlerImpl.java:131)
> at test.TestBean.getData (TestBean.java:74)
> ... 52 more
> 2006-02-22 13:01:10,489 44497 ERROR [TP-Processor3] [/ptd].[Faces Servlet] -
> Servlet.service() for servlet Faces Servlet threw exception
> javax.faces.FacesException : Cannot get value for _expression_ '#{test.data}'
> at
> org.apache.myfaces.context.servlet.ServletExternalContextImpl.dispatch(
> ServletExternalContextImpl.java:422)
> at org.apache.myfaces.application.jsp.JspViewHandlerImpl.renderView (
> JspViewHandlerImpl.java:234)
> at org.jenia.faces.template.handler.ViewHandler.renderView(
> ViewHandler.java:74)
> at org.apache.myfaces.lifecycle.LifecycleImpl.render(
> LifecycleImpl.java:372)
> at javax.faces.webapp.FacesServlet.service(FacesServlet.java:109)
> at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(
> ApplicationFilterChain.java :252)
> at org.apache.catalina.core.ApplicationFilterChain.doFilter(
> ApplicationFilterChain.java:173)
> at org.apache.myfaces.component.html.util.ExtensionsFilter.doFilter(
> ExtensionsFilter.java :129)
> at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(
> ApplicationFilterChain.java:202)
> at org.apache.catalina.core.ApplicationFilterChain.doFilter(
> ApplicationFilterChain.java :173)
> at org.apache.catalina.core.StandardWrapperValve.invoke(
> StandardWrapperValve.java:213)
> at org.apache.catalina.core.StandardContextValve.invoke(
> StandardContextValve.java :178)
> at org.apache.catalina.core.StandardHostValve.invoke(
> StandardHostValve.java:126)
> at org.apache.catalina.valves.ErrorReportValve.invoke(
> ErrorReportValve.java:105)
> at org.apache.catalina.core.StandardEngineValve.invoke(
> StandardEngineValve.java:107)
> at org.apache.catalina.connector.CoyoteAdapter.service(
> CoyoteAdapter.java:148)
> at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java
> :307)
> at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java
> :385)
> at org.apache.jk.common.ChannelSocket.invoke (ChannelSocket.java:748)
> at org.apache.jk.common.ChannelSocket.processConnection(
> ChannelSocket.java:678)
> at org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java
> :871)
> at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(
> ThreadPool.java:684)
> at java.lang.Thread.run(Thread.java:534)
> Caused by: org.apache.jasper.JasperException : Cannot get value for
> _expression_ '#{test.data}'
> at org.apache.jasper.servlet.JspServletWrapper.service(
> JspServletWrapper.java:370)
> at org.apache.jasper.servlet.JspServlet.serviceJspFile (
> JspServlet.java:291)
> at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
> at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter (
> ApplicationFilterChain.java:252)
> at org.apache.catalina.core.ApplicationFilterChain.doFilter(
> ApplicationFilterChain.java:173)
> at org.apache.catalina.core.ApplicationDispatcher.invoke (
> ApplicationDispatcher.java:672)
> at org.apache.catalina.core.ApplicationDispatcher.processRequest(
> ApplicationDispatcher.java:463)
> at org.apache.catalina.core.ApplicationDispatcher.doForward (
> ApplicationDispatcher.java:398)
> at org.apache.catalina.core.ApplicationDispatcher.forward(
> ApplicationDispatcher.java:301)
> at
> org.apache.myfaces.context.servlet.ServletExternalContextImpl.dispatch (
> ServletExternalContextImpl.java:416)
> ... 22 more
>
