Error calling Method on Managed Bean from another Managed Bean

Question

Hi
(Jdev 11.1.1.2.0)
Help please:
I have a managed bean (page flow scope) which is used by my main page for dynamic region flow navigation:
*public class RegionNavigationBean implements Serializable{*+
private String dynamicTaskFlowId = "/WEB-INF/home-task-flow-definition.xml#home-task-flow-definition";+
*public RegionNavigationBean() {*+
*public TaskFlowId getDynamicTaskFlowId() {*+
return TaskFlowId.parse(dynamicTaskFlowId);+
*public void setDynamicTaskFlowId(String taskFlowId) {*+
this.dynamicTaskFlowId = taskFlowId;+
taskFlowId property on main page def is set to +*${pageFlowScope.regionNavigationBean.dynamicTaskFlowId}*+
In a DB table (i.e. View Object on my model layer) I store a menu ID and a corresponding task_flow_id.
Then I have created an action listener class (RegionNavigationListener - page flow scope) which I link to my menu items on my main page (action listener property on menu item = +*#{pageFlowScope.regionNavigationAction.processAction}*+ )
In this action listener (processAction method), I retrieve the row set from the menu VO and find the record which matches my menu ID which caused the action event, thereby retrieving the task_flow_id which must be navigated to.
I then try to retrieve the instance of the RegionNavigationBean with the following statement: RegionNavigationBean regNav = (RegionNavigationBean)JSFUtils.getManagedBeanValue("regionNavigationBean");+
This seems to work fine, but as soon as I try and use this I get NullPointerException error, e.g.:
regNav.setDynamicTaskFlowId(menusRow.gettaskFlowId());+
or even:
System.out.println("%%% " + regNav.toString());+
This is all quite new to me... any help would be appreciated!
Thanks
Mario

Answer 1

Hi Mario,
I think JSFUtils.getManagedBeanValue(String) has difficult to evaluate the "regionNavigationBean" managed bean.
What JSFUtils.getManagedBeanValue(String) do is important. I remember that "JSF scoped" bean can be found by JSF style find method, such as requestScope, sessionScope, applicationScope. For a managed bean put in these scope, scope prefix is not needed, for example: using #{beanName} to locate a requestScope bean. The #{requestScope} prefix is not needed.
But pageFlowScope is different. If a bean is put in the pageFlowScope, you must use #{pageFlowScope.beanName} to locate it.
Say, ManagedBean is the java class of your manged bean.
FacesContext ctx = FacesContext.getCurrentInstance();
Application app = ctx.getApplication();
ManagedBean mb = (ManagedBean)app.evaluateExpressionGet(ctx, "#{pageFlowScope.managedBeanName}", ManagedBean.class);
Hope it helps.
Todd
Edited by: Todd Bao on Nov 26, 2009 9:58 PM