Question

one more time i’m in trouble here. My point is:
In my project i need a converter for (obviously) convert the items from the SelectOneMenu component to a list property in the respective bean. In my jsf page i have:

<p:selectOneMenu id="ddlPublicType" value="#{publicBean.selectedPublicType}"    effect="fade" converter="#{publicBean.conversor}" > 
    <f:selectItems value="#{publicoBean.lstPublicTypes}" var="pt" itemLabel="#{pt.label}" itemValue="#{pt.value}"></f:selectItems>
</p:selectOneMenu>

And my bean is:

@ManagedBean(name = "publicBean")
@RequestScoped
public class PublicBean {

// Campos
private String name; // Nome do evento
private TdPublicType selectedPublicType = null;
private List<SelectItem> lstPublicTypes = null;
private static PublicTypeDAO publicTypeDao; // DAO 

static {
    publicTypeDao = new PublicTypeDAO();
}
// Construtor

public PublicoBean() {

    lstPublicTypes = new ArrayList<SelectItem>();
    List<TdPublicType> lst = publicTypeDao.consultarTodos();
    ListIterator<TdPublicType> i = lst.listIterator();
    lst.add(new SelectItem("-1","Select..."));
    while (i.hasNext()) {
        TdPublicType actual = (TdPublicType) i.next();
        lstPublicTypes.add(new SelectItem(actual.getIdPublicType(), actual.getNamePublicType()));
    }

}

// Getters e Setters

...

public Converter getConversor() {
    return new Converter() {
        @Override
        public Object getAsObject(FacesContext context, UIComponent component, String value) {
            // This value parameter seems to be the value i had passed into SelectItem constructor
            TdPublicType publicType = null; // Retrieving the PublicType from Database based on ID in value parameter
            try {
                if (value.compareTo("-1") == 0 || value == null) {
                    return null;
                }
                publicType = publicTypeDao.findById(Integer.parseInt(value));
            } catch (Exception e) {
                FacesMessage msg = new FacesMessage("Error in data conversion.");
                msg.setSeverity(FacesMessage.SEVERITY_ERROR);
                FacesContext.getCurrentInstance().addMessage("info", msg);
            }
            return publicType;
        }

        @Override
        public String getAsString(FacesContext context, UIComponent component, Object value) {
            return value.toString(); // The value parameter is a TdPublicType object ?
        }
    };
}

...
}

In the getAsObject() method, the value parameter seems to be the value i had passed into SelectItem constructor. But in the getAsString() method, the value also seems to be a string representation of an Id. This parameter shouldn’t be of type TdPublicType ? There is anything wrong in my code?

Answer 1

The getAsString() should convert the Object (which is in your case of type TdPublicType) to a String which uniquely identifies the instance, e.g. some ID, so that it can be inlined in HTML code and passed around as HTTP request parameters. The getAsObject() should convert exactly that unique String representation back to the concrete Object instance, so that the submitted HTTP request parameter can be converted back to the original object instance.

Basically (trivial prechecks and exception handling omitted):

@Override
public String getAsString(FacesContext context, UIComponent component, Object modelValue) throws ConverterException {
    // Convert Object to unique String representation for display.
    return String.valueOf(((TdPublicType) modelValue).getId());
}

@Override
public Object getAsObject(FacesContext context, UIComponent component, String submittedValue) throws ConverterException {
    // Convert submitted unique String representation back to Object.
    return tdPublicTypeService.find(Long.valueOf(submittedValue));
}

---

Update: you’ve another problem, you’re specifying the value property of TdPublicType class as the item value instead of the TdPublicType instance itself. This way the converter will retrieve the value property instead of the TdPublicType instance in the getAsString(). Fix it accordingly:

<f:selectItems value="#{publicoBean.lstPublicTypes}" var="pt" 
    itemLabel="#{pt.label}" itemValue="#{pt}"/>