如何在JSF2中正确使用f：selectItem？

Question

guys I need to update another selectOneMenu when the User selects one option of combo_pedido_tipoplm selectOneMenu. If the user selects the "Chose One" option it needs to clear the second one.

I've tried everything but I cant call my actionListener after I've selected the Option "Chose one" (Selecione) from my h:selectOneMenu.

XHTML

<h:selectOneMenu id="combo_pedido_tipoplm" value="#mBeanManterPedido.tipoPlacaMaeFiltro}" required="true" disabled="#{!mBeanManterPedido.pedidoValido or mBeanManterPedido.clonado}">
    <f:selectItem itemLabel="#{msgTemplate.lblSelecione}" />
    <f:selectItems value="#{mBeanManterPedido.selectItemsTipoPlacaMae}" />
    <p:ajax event="change" listener="#{mBeanManterPedido.tipoPlacaMaeChange}"   process="@this"/>
</h:selectOneMenu>

MBean

private TipoPlacaMae tipoPlacaMaeFiltro;

public void popularTipoPlacaMae() {
        this.selectItemsTipoPlacaMae = new ArrayList<SelectItem>();
        for (TipoPlacaMae tipoplaca : TipoPlacaMae.values()) {
            this.selectItemsTipoPlacaMae.add(new SelectItem(tipoplaca, tipoplaca.getNome()));
        }
        UtilsCommon.orderByLabel(selectItemsTipoPlacaMae);
    }

public void tipoPlacaMaeChange(AjaxBehaviorEvent e) {
        // deseleciona a PlacaMae atualmente selecionada.
        pedido.setPlacaMae(null);
        limparDadosPedido();
        popularPlacaMae();
    }

if I select the option "Chose one" I got a validation error because this selectOneMenu is requeried and my setter for tipoPlacaMaeFiltro is not called.

<?xml version='1.0' encoding='UTF-8'?>

{"validationFailed":true}

What can I do about it ?

Answer 1

For those that have the same doubt.

You need to put the immediate="true" in your ajax request.

<h:selectOneMenu id="id"
                    value="#{mbean.value}" required="#{mbean.required}"
                    converter="#{mbean.converter}">
                    <f:selectItem itemLabel="Chose one" />
                    <f:selectItems value="#{mbean.selectItems}" />
                    <f:ajax event="valueChange"  listener="#{mbean.onchange}"
                        render="second_combo"
                        immediate="true">
                    </f:ajax>
                </h:selectOneMenu>

After that in the ManagedBean you need to implements but handle differently the listener

public void onchange(AjaxBehaviorEvent e) {
    YourClass o = getSelectedValue(e);
}


private YourClass getSelectedValue(AjaxBehaviorEvent e)
{
    if (e != null)
    {   
        UISelectOne select = (UISelectOne) e.getSource();
        if (select.getSubmittedValue() == null ||
                select.getSubmittedValue().toString().isEmpty()) {
            return null;
        }
        else {          
            String id = select
                    .getSubmittedValue().toString();
                return ObjectThatImplementsConverterInterface.getAsObject(FacesContext.getCurrentInstance(), select, id);
        }
    }
    return null;
}

Unfortunally you must handle that way because if you don't do the user can selects "Chose One" and the mbean.value will be OK (null) after that the second selection in the same SelectOneMenu will trigger with the previous selected value (null). I don't know if it happens with everybody or just me.

Bye.