GET parameters not being passed to ViewScoped ManagedBean

Question

I have a p:dataTable with p:contextMenu and some p:menuitems. One of these menu items should pass on an id to another view which is read like pointed out here.

The thing is the converter throws the required message like the id wasn't sent - and it seems like it truly isn't. I think I'm missing something basic, but I really couldn't figure it out. Here's the code:

The source view

<h:form id="formTabela">
    <p:fieldset>
        <p:dataTable id="sistemas"
                     selection="#{sistemaMb.sistemaSelecionado}">
            (...)
        </p:dataTable>
    </p:fieldset>

    <p:contextMenu for="sistemas">
        <p:menuitem value="Gerenciar módulos" icon="ui-icon-search" 
                    action="modulos?faces-redirect=true&amp;includeViewParams=true"
                    ajax="false">  
            <f:param name="id" value="#{sistemaMb.sistemaSelecionado.id}"/>
        </p:menuitem>

        (More items...)
    </p:contextMenu>

    (Some dialogs...)
</h:form>

Target view (modulos)

<!-- This is on body: -->
<ui:define name="metadata">
    <f:metadata>
        <f:viewParam name="id" value="#{moduloMb.sistema}" 
                     converterMessage="foo"
                     required="true" 
                     requiredMessage="bar"/>

        <f:event type="preRenderView" listener="#{moduloMb.init()}" />
    </f:metadata>
</ui:define>

Target view managed bean

@ManagedBean
@ViewScoped
public class ModuloMb implements Serializable {
    private Sistema sistema;

    @PostConstruct
    public void init() {
        if (!Faces.isPostback() && !Faces.isValidationFailed()) {
            // business stuff, but "sistema" is always null.
        }
    }

    public Sistema getSistema() {
        return sistema;
    }

    public void setSistema(Sistema sistema) {
        this.sistema = sistema;
    }

    (...)

}

The converter

@FacesConverter(forClass = Sistema.class)
public class SistemaConverter implements Converter {

    private final SistemaService sistemaService = lookup(SistemaService.class);

    @Override
    public Object getAsObject(FacesContext context, UIComponent component, 
                              String value) {
        if (value == null || !value.matches("\\d+")) {
            return null;
        }

        Optional<Sistema> optSistema = sistemaService.find(Short.valueOf(value));
        if (!optSistema.isPresent())
            throw new ConverterException(
                    new FacesMessage("Id de sistema inválido " + value));
        return optSistema.get();
    }

    @Override
    public String getAsString(FacesContext context, UIComponent component, 
                              Object value) {
        if (!(value instanceof Sistema) || ((Sistema) value).getId() != null) {
            return null;
        }

        return ((Sistema) value).getId().toString();
    }

}

Answer 1

The includeViewParams directive which you use in the outcome string for the p:menuitem tells JSF to insert the special set of view parameters as request parameters in the GET request to your target view.

BUT, f:param does not define a view param and neither will it be appended to the URL to which the GET request is done.

It does work if you append the parameter directly to the implicit navigation outcome: "modulod?faces-redirect=true&id=..."