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Editorial Team
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Asked: 2026-05-20T12:37:20+00:00

Let’s say I have five or more input computers that can affect whether a

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Let’s say I have five or more input computers that can affect whether a single drop down menu is displayed. The issue I am running into is that if the drop down menu is displayed once (thus setting the value in the backing bean through ajax) and the user then changes one of the affecting input components, then the backing bean value of the drop down menu is not getting reset when the drop down goes into hiding using the rendered property. For example:

    <h:selectOneMenu id="sampleDropDown" required="false" immediate="true"
        onchange="jsUpdateSampleDropDownValue()" value="#{backingBean.value}" 
        rendered="#{backingBean.shouldShowSampleDropDown}" 
        actionListener="#{backingBean.listener}" />

I understand that I have options here. I’ve debated whether I should add a generic ValueChangeListener (apply request values phase) or an EventHandler (render response phase) that would listen in on the values of the other inputs and make a decision on whether to clear the drop down menu value but this certainly is more work then just letting the rendered property make that decision.

We’ve seen dozens of the same type of issue on the project I’m currently on and I’d really like to hear from the experts on the best practice for handling this type of situation. In case it matters we are using custom ajax (not ajax4jsf) and jsf 1.1. Any help is appreciated.

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1 Answer

  1. Editorial Team

    The solution I came up with is to not try and reset the input component in the backing bean value of the renderered property.

    I have a phase listener attached to the single page interface and am essentially passing request parameters in the javascript method (i.e. jsUpdateSampleDropDownValue()) so that business logic data can be loaded in the rendered response phase using the chain of responsibility pattern.

    When a request parameter is passed (i.e. RESET_SAMPLE_DROP_DOWN) onchange that matches a corresponding event handler (i.e. ResetSampleDropDownEventHandler), I check a separate “constraint” class (see Hardcore Java book) that validates whether enough data is accumulated before either clearing the binding value or continuing with the request.

    This allows the logic to be centralized yet be attached to multiple components. You may be asking why a single JSF ValueChangeListener was not attached to each component which would allow the same re-use. The reason for this is because our business logic takes place in the render response phase after the update model phase so it makes sence that any “reset” type methods occur after any “defaulting” of values.

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