How to write a custom converter for <p:pickList>

Question

How can I write a custom converter when working with PrimeFaces components that use a list of POJO? My particular problem is with <p:pickList>

<p:pickList converter="????" value="#{bean.projects}" var="project" 
                             itemLabel="#{project.name}" itemValue="#{project}">

Without a converter I get java.lang.ClassCastException because JSF sets the submitted values with unconverted java.lang.String submitted values.

Answer 1

It's possible, whithout other database access, but i don't know the best way. I use a very specific converter, works only for picklist. Try this:

@FacesConverter(value = "primeFacesPickListConverter")public class PrimeFacesPickListConverter implements Converter {
@Override
public Object getAsObject(FacesContext arg0, UIComponent arg1, String arg2) {
    Object ret = null;
    if (arg1 instanceof PickList) {
        Object dualList = ((PickList) arg1).getValue();
        DualListModel dl = (DualListModel) dualList;
        for (Object o : dl.getSource()) {
            String id = "" + ((Project) o).getId();
            if (arg2.equals(id)) {
                ret = o;
                break;
            }
        }
        if (ret == null)
            for (Object o : dl.getTarget()) {
                String id = "" + ((Project) o).getId();
                if (arg2.equals(id)) {
                    ret = o;
                    break;
                }
            }
    }
    return ret;
}

@Override
public String getAsString(FacesContext arg0, UIComponent arg1, Object arg2) {
    String str = "";
    if (arg2 instanceof Project) {
        str = "" + ((Project) arg2).getId();
    }
    return str;
}

and Picklist:

<p:pickList converter="primeFacesPickListConverter" value="#{bean.projects}" var="project" 
                        itemLabel="#{project.name}" itemValue="#{project}">

Work's for me, improvements is necessary.