Item selected in p:selectOneMenu reaches null in Systener

Question

I have a p:selectOneMenu, with data coming from the database, within a p:dialog, along with a p:messages and other fields. I want to perform an action (Display some messages) when selecting a certain option in p:selectOneMenu, but I get a nullPointerException because the value arrives null in the Listener method of p:ajax. I’ve tried using the onchange="submit();" in p:selectOneMenu, nullPointerException stops, but the method simply does not execute and no Exception is shown, just nothing happens.

Dialog

<p:dialog id="dialogRelato"
                  showEffect="fade" hideEffect="fade"
                  modal="true" header="Novo Relato"
                  widgetVar="dialogRelato" minHeight="40"
                  resizable="false">

            <p:messages id="menssagens" autoUpdate="true" closable="true" />

                <b>
                    <h:outputLabel value="Tipo de Relato: " />
                </b>
                <p:selectOneMenu style="height: 20px; width: 200px;"
                                 value="#{livroOrdemController.tipoRelatoSelecionado}"
                                 converter="tipoRelatoConverter">
                    <f:selectItems value="#{livroOrdemController.preencherComboTiposRelatos()}"/>
                    <p:ajax event="change" listener="#{livroOrdemController.onSelectItemMenuChange()}" process="@this" />
                </p:selectOneMenu>
                <br />
                <br />
            <p:calendar id="calendarDataOcorrencia"
                            pattern="dd/MM/yyyy"
                            locale="pt_BR"
                            showOn="button"
                            value="#{livroOrdemController.dataOcorrencia}">
                    <p:ajax event="dateSelect" listener="#{livroOrdemController.onDataOcorrenciaSelect()}"/>
                </p:calendar>
  </p:dialog>

Method in Managed Bean

public void onSelectItemMenuChange() {
   if(tipoRelatoSelecionado.getDescricao().equals("Acidentes e Danos")) {
       FacesUtils.mensErro("Teste Listener");
   }
}

Convert

@FacesConverter(value="tipoRelatoConverter")
public class TipoRelatoConverter implements Converter {

public TipoRelatoConverter() {
}

@Override
public Object getAsObject(FacesContext context, UIComponent component, String string) {
    if (string == null || string.equals("Selecione...")) {
        return null;
    }

    Long id = Long.parseLong(string);
    TipoRelato tipoRelato = new TipoRelato();
    tipoRelato.setIdTipoRelato(id);

    return tipoRelato;
}

@Override
public String getAsString(FacesContext context, UIComponent component, Object object) {
    if (object == null) {
        return null;
    }

    if(object instanceof TipoRelato) {
        TipoRelato tipoRelato = (TipoRelato) object;

        return "" + tipoRelato.getIdTipoRelato();
    } 

    else {
        throw new IllegalArgumentException("object:" + object + "of type:" + 
                object.getClass().getName() + "; expected type:br.org.web.entities.TipoRelato");
    }
}

}

Answer 1

On the first question:

Description not available on @Managedbean

Evaluating the code of TipoRelatoConverter, in fact the description is not being used:

Long id = Long.parseLong(string); 
TipoRelato tipoRelato = new TipoRelato();
tipoRelato.setIdTipoRelato(id);

This way only the report id is being passed to the return object.

To keep your whole object you must change the implementation of your converter to save or fetch the converted object again.

In this link you can check some examples of converters to keep the whole entity. Another example on how to fetch the entity again can be seen in this post from Balusc

I believe that the implementation of the first link is simpler.

Sorry for the delay, I hope I’ve helped!

Answer 2

I believe in your f:selectItemslack the itemValue, it is the attribute that will be assigned in the variable livroOrdemController.tipoRelatoSelecionado, replace with this and I believe it will work:

<f:selectItems value="#{livroOrdemController.preencherComboTiposRelatos()}" var="itemTipoRelato" itemValue="#{itemTipoRelato}"/>