Please help me to find the solution.
this is the xhtml code:
<p:selectOneMenu value="#{activteBean.act.activiteFamille}" 
    converter="familleAct"
    var="f" required="Une famille est obligatoire" >
    <f:selectItems value="#{activteBean.actFamList}" var="famille" itemLabel="#        {famille.dsgFam}" itemValue="#{famille}"/>  
    <p:column>#{f.refFam}</p:column>  
    <p:column>#{f.dsgFam}</p:column>  
</p:selectOneMenu>   
here is my converter:
@FacesConverter(forClass=ActiviteFamille.class,value="familleAct" )
public class ActiviteFamilleConverter implements Converter {
@Override
public Object getAsObject(FacesContext arg0, UIComponent arg1, String code) {
    if (code.trim().equals("")) {
        return null;
    } else {
        ActiviteFamilleDao actFamDao = new ActiviteFamilleDao();
        List<ActiviteFamille> actFamList = actFamDao.findAll();
        for (ActiviteFamille af : actFamList) {
            if (af.getRefFam().equals(code)) {
                return af;
            }
        }
    }
    return null;
}
@Override
public String getAsString(FacesContext arg0, UIComponent arg1, Object value) {
    if (value == null || value.equals("")) {
        return "";
    } else {
        return String.valueOf(((ActiviteFamille) value).getRefFam());
    }
}
}
The managed bean:
@ManagedBean(name = "activteBean")
@ViewScoped
public class ActivteBean implements Serializable {
private Activite act = new Activite();
private ActiviteDao actDao = new ActiviteDao();
private List<Activite> actList;
private boolean init;
private ActiviteFamilleDao actFamDao = new ActiviteFamilleDao();
private List<ActiviteFamille> actFamList;
public boolean isInit() {
    act = new Activite();
    actList = actDao.findAll();
    actFamList=actFamDao.findAll();
    return init;
}
....
}
and thank you for your help.
 
    