7.4. Propagating request parameters

If only the name attribute is specified, the request parameter is propagated with the PAGE context (that is, it is not mapped to model property).

<pages> 
  <page view-id="/hello.jsp" action="#{helloWorld.sayHello}"> 
    <param name="firstName" /> 
    <param name="lastName" /> 
  </page> 
</pages>

<pages> 
  <page view-id="/hello.jsp" action="#{helloWorld.sayHello}"> 
    <param name="firstName" /> 
    <param name="lastName" /> 
  </page> 
</pages>

Page parameter propagation is especially useful when building multi-layered master-detail CRUD pages. You can use it to "remember" your view (for example, when pressing the Save button), and which entity you were editing.

Although this is fairly complex, it is definitely worthwhile to dedicate time to an understanding of page parameters. They are the most elegant method of propagating state across non-Faces requests. They are particularly useful in certain situations. For example, if we have search screens with bookmarkable results pages, page parameters let us write handling for both POST and GET requests in the same code. Page parameters eliminate repetitive request parameter-listing in the view definition, and simplify redirect code.