JSF page does not retrieve values from back bean - ajax

Question

I'm doing a dynamic view according to a dropdown selection:
there's the code:
<h:selectOneMenu value="#{controller.type}" >
<p:ajax listener="#{controller.switchPanels}" update="panels" />
<f:selectItem itemValue="1" itemLabel="option 1" />
<f:selectItem itemValue="2" itemLabel="option 2" />
</h:selectOneMenu>
<h:panelGroup layout="block" id="panels">
<h:panelGroup layout="block" rendered="#{controller.type == '1'}" >
<h:inputText value="#{controller.value}" >
<f:validateRegex pattern="^[0-9a-zA-Z ]*$" />
</h:inputText>
</h:panelGroup>
<h:panelGroup layout="block" rendered="#{controller.type == '2'}" >
Panel 2
</h:panelGroup>
</h:panelGroup>
<h:commandLink action="#{controller.go}">Go</h:commandLink>
The controller:
#ViewScoped
#ManagedBean
public class Controller {
String type = "1";
String value;
// getters and setters
public void switchPanels(AjaxBehaviorEvent event) {
this.value = "";
}
public void go(){
}
...
}
Try this scenario:
- write special characters in the value field
- press Go (causes the validation message to popup)
- try changing the selection and reselect the same panel again
The result is that the field is not cleared even though I clear it in the switchPanels method
Please any explanation would be helpful
Thank you