NPE while trying to render a View in Spring Webflow

Question

When trying to use a webflow, I keep getting the following error:

{
    "failure":"true",
    "exception.message":"org.springframework.webflow.execution.ActionExecutionException: Exception thrown executing org.springframework.webflow.action.ViewFactoryActionAdapter@200a5beb in state 'accountCannotLogInView' of flow 'login' -- action execution attributes were 'map[[empty]]'",
    "exception.stacktrace":"org.springframework.webflow.execution.ActionExecutionException: Exception thrown executing org.springframework.webflow.action.ViewFactoryActionAdapter@200a5beb in state 'accountCannotLogInView' of flow 'login' -- action execution attributes were 'map[[empty]]'
    ...
    Caused by: java.lang.IllegalStateException: Exception occurred rendering view null
        at org.springframework.webflow.mvc.view.AbstractMvcView.render(AbstractMvcView.java:191)
        at org.springframework.webflow.action.ViewFactoryActionAdapter.doExecute(ViewFactoryActionAdapter.java:40)
        at org.springframework.webflow.action.AbstractAction.execute(AbstractAction.java:188)
        at org.springframework.webflow.execution.ActionExecutor.execute(ActionExecutor.java:51)
        ... 66 more
    Caused by: java.lang.NullPointerException
        at org.springframework.webflow.mvc.servlet.ServletMvcView.doRender(ServletMvcView.java:50)
        at org.springframework.webflow.mvc.view.AbstractMvcView.render(AbstractMvcView.java:187)
        ... 69 more
    "
}

Does anybody have any idea what the cause of this might be? From my login-webflow.xml:

<action-state id="checkAccountType">
    <evaluate expression="lookupAccountTypeAction.lookup(flowScope.principal)" />
    <transition on="EMAIL" to="accountCannotLogInView" />
    <transition on="Login" to="checkAccountStatus" />
    <transition on="CONTACT" to="accountCannotLogInView" />
</action-state>

<end-state id="accountCannotLogInView" view="myAccountCannotLogInView"/>

From default_views.properties:

myAccountCannotLogInView.(class)=org.springframework.web.servlet.view.JstlView
myAccountCannotLogInView.url=/WEB-INF/view/jsp/default/ui/myAccountCannotLogInView.jsp

From my log file:

2013-09-09 08:29:25,645 DEBUG [org.springframework.webflow.engine.EndState] - Entering state 'accountCannotLogInView' of flow 'login'
2013-09-09 08:29:25,645 DEBUG [org.springframework.webflow.execution.ActionExecutor] - Executing org.springframework.webflow.action.ViewFactoryActionAdapter@359d136a
2013-09-09 08:29:25,645 DEBUG [org.springframework.webflow.mvc.view.AbstractMvcView] - Rendering MVC [null] with model map [{flowRequestContext=[RequestControlContextImpl@55bf756b externalContext = org.springframework.webflow.mvc.servlet.MvcExternalContext@2bb4d74, currentEvent = EMAIL, requestScope = map['ticketGrantingTicketId' -> 'TGT-1-GxALVR7PEtbagbnRlStOTbHoRHlb61YVm1m2hvWx3pgWCEXgPb-cas01.example.org'], attributes = map[[empty]], messageContext = [DefaultMessageContext@cb5efc8 sourceMessages = map[[null] -> list[[empty]]]], flowExecution = [FlowExecutionImpl@3f5c0d33 flow = 'login', flowSessions = list[[FlowSessionImpl@419d87bc flow = 'login', state = 'accountCannotLogInView', scope = map['principal' -> sso_test_user, 'userInfoBean' -> com.mycompany.authentication.UserInfoBean@54394557[username=<null>,firstName=<null>,lastName=<null>,emailAddress=<null>,streetAddress=<null>,city=<null>,state=<null>,zip=<null>,country=<null>], 'changePasswordBean' -> com.mycompany.authentication.ChangePasswordBean(username=null, newPassword=null, confirmNewPassword=null), 'service' -> https://my.server.com:443/casauth/facade/norenew?idp=https://my.server.com/idp/externalAuthnCallback, 'credentials' -> [username: sso_test_user], 'warnCookieValue' -> false, 'ticketGrantingTicketId' -> 'TGT-1-GxALVR7PEtbagbnRlStOTbHoRHlb61YVm1m2hvWx3pgWCEXgPb-cas01.example.org']]]]], flashScope=map[[empty]], principal=sso_test_user, currentUser=null, userInfoBean=com.mycompany.authentication.UserInfoBean@54394557[username=<null>,firstName=<null>,lastName=<null>,emailAddress=<null>,streetAddress=<null>,city=<null>,state=<null>,zip=<null>,country=<null>], changePasswordBean=com.mycompany.authentication.ChangePasswordBean(username=null, newPassword=null, confirmNewPassword=null), service=https://my.server.com:443/casauth/facade/norenew?idp=https://my.server.com/idp/externalAuthnCallback, credentials=[username: sso_test_user], flowExecutionKey=e1s1, warnCookieValue=false, flowExecutionUrl=/authentication/login?username=%5BLjava.lang.String%3B%405b65afa5&submit=%5BLjava.lang.String%3B%4070eea883&_eventId=%5BLjava.lang.String%3B%4044796a61&service=%5BLjava.lang.String%3B%407f372965&lt=%5BLjava.lang.String%3B%407e7ee722&password=%5BLjava.lang.String%3B%403d78aa0f&execution=%5BLjava.lang.String%3B%403ce4de50, ticketGrantingTicketId=TGT-1-GxALVR7PEtbagbnRlStOTbHoRHlb61YVm1m2hvWx3pgWCEXgPb-cas01.example.org}]
2013-09-09 08:29:25,645 DEBUG [org.springframework.webflow.engine.impl.FlowExecutionImpl] - Attempting to handle [org.springframework.webflow.execution.ActionExecutionException: Exception thrown executing org.springframework.webflow.action.ViewFactoryActionAdapter@359d136a in state 'accountCannotLogInView' of flow 'login' -- action execution attributes were 'map[[empty]]'] with root cause [java.lang.NullPointerException]
2013-09-09 08:29:25,645 DEBUG [org.springframework.webflow.engine.impl.FlowExecutionImpl] - Rethrowing unhandled flow execution exception

And yes, the file does exist in that location. I've been banging on this for a few days, so if anybody has any insight, I'd really appreciate it.

Answer 1

And the correct answer is "user error". I'm building CAS via maven. I created profiles to hold logging, and then incorrectly configured it so that the default_views.properties file wasn't in the profiles. As a result, when CAS did its overlay as part of the maven build, it included the baseline default_views.properties instead of my copy.

Answer 2

it seems like your property is not parsed to your flow.xml.

defining your view hardcoded should work.

see here: Specifying view identifiers

Answer 3

The reason for this issue is: The JSP view is not found.

In cas-servlet.xml, mention the properties file which has the basename of the custom JSP view inside the "viewResolver" bean as below:

<bean id="viewResolver"
    class="org.springframework.web.servlet.view.ResourceBundleViewResolver"
    p:order="0">
    <property name="basenames">
        <util:list>
            <value>${cas.viewResolver.basename}</value>
            <value>custom_view</value>
            <value>protocol_views</value>
        </util:list>
    </property>
</bean>

And in the custom_view.properties, mention the following:

casRegisterView.(class)=org.springframework.web.servlet.view.JstlView
casRegisterView.url=/WEB-INF/view/jsp/default/ui/casRegisterView.jsp

Here the JSP view is "casRegisterView.jsp". Place custom_view.properties in /src/main/resources.