public class ResetInputAjaxActionListener
extends DefaultPhaseListener
implements ActionListener

Use this action listener when you want to partially (ajax) render input fields which are not executed during submit, but which are possibly in an invalidated state because of a validation failure during a previous request. Those input fields will be resetted so that they are not in an invalidated state anymore.

How does it work? First, here are some JSF facts:

• When JSF validation succeeds for a particular input component during the validations phase, then the submitted value is set to null and the validated value is set as local value of the input component.
• When JSF validation fails for a particular input component during the validations phase, then the submitted value is kept in the input component.
• When at least one input component is invalid after the validations phase, then JSF will not update the model values for any of the input components. JSF will directly proceed to render response phase.
• When JSF renders input components, then it will first test if the submitted value is not null and then display it, else if the local value is not null and then display it, else it will display the model value.
• As long as you're interacting with the same JSF view, you're dealing with the same component state.

So, when the validation has failed for a particular form submit and you happen to need to update the values of input fields by a different ajax action or even a different ajax form (e.g. populating a field depending on a dropdown selection or the result of some modal dialog form, etc), then you basically need to reset the target input components in order to get JSF to display the model value which was edited during invoke action. Otherwise JSF will still display its local value as it was during the validation failure and keep them in an invalidated state.

The ResetInputAjaxActionListener is designed to solve exactly this problem. There are basically three ways to configure and use it:

• Register it as <phase-listener> in faces-config.xml. It'll be applied to every single ajax action throughout the webapp, on both UIInput and UICommand components.

   <lifecycle>
     <phase-listener>org.omnifaces.eventlistener.ResetInputAjaxActionListener</phase-listener>
   </lifecycle>
   

• Or register it as <action-listener> in faces-config.xml. It'll only be applied to ajax actions which are invoked by an UICommand component such as <h:commandButton> and <h:commandLink>.

   <application>
     <action-listener>org.omnifaces.eventlistener.ResetInputAjaxActionListener</action-listener>
   </application>
   

• Or register it as <f:actionListener> on the invidivual UICommand components where this action listener is absolutely necessary to solve the concrete problem. Note that it isn't possible to register it on the individual UIInput components using the standard JSF tags.

   <h:commandButton value="Update" action="#{bean.updateOtherInputs}">
     <f:ajax execute="currentInputs" render="otherInputs" />
     <f:actionListener type="org.omnifaces.eventlistener.ResetInputAjaxActionListener" />
   </h:commandButton>
   

This works with standard JSF, PrimeFaces and RichFaces actions. Only for RichFaces there's a reflection hack, because its ExtendedPartialViewContextImpl always returns an empty collection for render IDs. See also RF issue 11112.

Design notice: being a phase listener was mandatory in order to be able to hook on every single ajax action as standard JSF API does not (seem to?) offer any ways to register some kind of AjaxBehaviorListener in an application wide basis, let alone on a per <f:ajax> tag basis, so that it also get applied to ajax actions in UIInput components. There are ways with help of SystemEventListener, but it ended up to be too clumsy.