[Myfaces Wiki] Update of "AccessingOneManagedBeanFromAnother" by SimonKitching

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The following page has been changed by SimonKitching:
http://wiki.apache.org/myfaces/AccessingOneManagedBeanFromAnother

The comment on the change is:
Moved info from FAQ to its own page.

New page:
=== How can I access one Managed Bean from another? ===

There are two ways for one managed bean to access another managed bean in the same webapp:

==== Using Dependency Injection ====

In your project's faces configuration file which defines the managed beans, a managed bean
property can be declared as initialised with a reference to another managed bean:

{{{
 <managed-bean>
   <managed-bean-name>neededBean</managed-bean-name>
   <managed-bean-class>fqn.to.NeededBean</managed-bean-class>
   <managed-bean-scope>session</managed-bean-scope>
 </managed-bean>

 <managed-bean>
   <managed-bean-name>usingBean</managed-bean-name>
   <managed-bean-class>fqn.to.UsingBean</managed-bean-class>
   <managed-bean-scope>request</managed-bean-scope>
   <managed-property>
     <property-name>neededBean</property-name>
     <value>#{neededBean}</value>
   </managed-property>
 </managed-bean>
}}}

The constraints are that:
 * the using bean must have scope which is the same as or shorter than the needed bean
 * the using bean must have a property-setter method which takes the needed bean as a parameter

==== Using Lookup ====

The following java code can be used to explicitly look up an arbitrary managed bean by name:
{{{
FacesContext facesContext = FacesContext.getCurrentInstance();
NeededBean neededBean
    = (NeededBean) facesContext.getApplication()
      .getVariableResolver().resolveVariable(facesContext, "neededBean");
}}}
Alternately, you can use this code to evaluate any JSF EL expression.
{{{
FacesContext facesContext = FacesContext.getCurrentInstance();
NeededBean neededBean
    = (NeededBean)facesContext.getApplication()
      .createValueBinding("#{neededBean}").getValue(facesContext);
}}}