overriding a session-scoped Managed Bean with a subclass

Question

In a JSF 1.2 application, can I override a session-scoped Managed Bean returned with a subclass?

Class structure

I have a session-scoped Managed Bean, MainViewMB, and its subclass, RestrictedViewMB:

UML: <<ManagedBean>> MainViewMB extended by RestrictedViewMB

faces-config.xml

<managed-bean>
  <managed-bean-name>mainViewMB</managed-bean-name>
  <managed-bean-class>com.example.MainViewMB</managed-bean-class>
  <managed-bean-scope>session</managed-bean-scope>
</managed-bean>

Problem statement

The EL expression #{mainViewMB} returns an instance of MainViewMB.

I would like to rebind the name #{mainViewMB} with an instance of RestrictedViewMB, so that the EL expression #{mainViewMB} returns an instance of the subclass for the rest of the session.

Is there a way to accomplish my goal?

Motivating example

MainViewMB handles the GUI logic behind the application's main page. When a user enters the application from a special-purpose login page, I need to provide a restricted, simplified view of the main page. Overriding some of MainViewMB's properties in a subclass seems the obvious solution.

BalusC BalusC · Accepted Answer · 2013-11-26T17:47:06

Do it manually at the moment you can/need to do it.

externalContext.getSessionMap().put("mainViewMB", new RestrictedViewMB());

This puts a new instance of RestrictedViewMB in the session scope with the name mainViewMB, effectively making it a session scoped managed bean.

You only need to take into account that managed properties and @PostConstruct/@PreDestroy are not invoked this way, you'd also have to do it manually.

overriding a session-scoped Managed Bean with a subclass

1 Answers