6/22/07

JSF code snippet: Page scope with Tomahawk save state component

JSF code snippet: Page scope with Tomahawk save state component
By default, JSF backing beans can be only in session or request scope. Having a "page" scope is very useful, so the state is maintained between requests, but is discared when you abandon the page (and not kept in the session). You can easily achieve this by using the UI save state component from MyFaces Tomahawk project.
The bean saved by saveState must be serializable (if you have a dataModel don't forget to declare it transient) and declared of request scope in faces-config.xml

In the jsp
< t:saveState id="saveState" value="#{BackingBean}" />

In web.xml
< context-param>
< param-name> javax.faces.STATE_SAVING_METHOD < /param-name>
< param-value>client < /param-value>
< /context-param>

< filter>
< filter-name>extensionsFilter < /filter-name>
< filter-class> org.apache.myfaces.component.html.util.ExtensionsFilter < /filter-class>
< /filter>


In faces-config.xml
< navigation-rule>
< from-view-id>/myScreen.jsp < /from-view-id>
< navigation-case>
< from-outcome>cancel < /from-outcome>
< to-view-id>/myScreen.jsp < /to-view-id>
< /navigation-case>
< /navigation-rule>
< managed-bean>
< managed-bean-name>BackingBean < /managed-bean-name>
< managed-bean-class>myPackage.BackingBean < /managed-bean-class>
< managed-bean-scope>request < /managed-bean-scope>
< /managed-bean>

The navigation rule to the same screen on cancel has the nice effect of clearing the saved values. That makes implementing a "Clear" button just that easy.
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