⁠8.2. Page actions

A Seam page action is an event occurring immediately before a page is rendered. Declare page actions in WEB-INF/pages.xml. You can define a page action for a particular JSF view ID: 
​<pages> 
​ <page view-id="/hello.xhtml" action="#{helloWorld.sayHello}"/>
​</pages>
Or you can use a * wildcard as a suffix to the view-id to specify an action that applies to all view IDs that match that pattern: 
​<pages> 
​    <page view-id="/hello/*" action="#{helloWorld.sayHello}"/> 
​</pages>

Note

If the <page> element is defined in a fine-grained page descriptor, the view-id attribute can be omitted, as it is already implied.
If multiple page actions, with wildcards, match the current view-id; Seam calls all the actions, in the order of least-specific to most-specific.
The page action method can return a JSF outcome. If the outcome is not null, Seam uses the defined navigation rules to navigate to a view.
The view ID mentioned in the <page> element need not correspond to a real JSP or Facelets page. This way, you can reproduce the functionality of a traditional action-oriented framework like Struts or WebWork using page actions. This is useful for performing complex actions in response to non-Faces requests like HTTP GET.
Multiple or conditional page actions can be specified with the <action> tag: 
​<pages> 
​  <page view-id="/hello.xhtml">
​    <action execute="#{helloWorld.sayHello}" 
​            if="#{not validation.failed}"/>
​    <action execute="#{hitCount.increment}"/> 
​  </page> 
​</pages>
Page actions are executed on both an initial (non-Faces) request and a postback (Faces) request. If you use the page action to load data, it may conflict with the standard JSF actions being executed on a postback. One way to disable the page action is to set up a condition that resolves to true only upon an initial request. 
​<pages> 
​  <page view-id="/dashboard.xhtml"> 
​    <action execute="#{dashboard.loadData}" 
​      if="#{not FacesContext.renderKit.responseStateManager.isPostback(FacesContext)}"/> 
​  </page> 
​</pages>
This condition consults the ResponseStateManager#isPostback(FacesContext) to determine if the request is a postback. The ResponseStateManager is accessed using FacesContext.getCurrentInstance().getRenderKit().getResponseStateManager().
Seam offers a built-in condition that accomplishes this result less verbosely. You can disable a page action on a postback by setting the on-postback attribute to false: 
​<pages> 
​    <page view-id="/dashboard.xhtml"> 
​    <action execute="#{dashboard.loadData}" on-postback="false"/> 
​    </page> 
​</pages>
The on-postback attribute defaults to true to maintain backward compatibility.