@Override
 public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
   if (object == null) {
     return null;
   }
   if (object instanceof CarritoCompras) {
     CarritoCompras o = (CarritoCompras) object;
     return getStringKey(o.getIdCarrito());
   } else {
     Logger.getLogger(this.getClass().getName())
         .log(
             Level.SEVERE,
             "object {0} is of type {1}; expected type: {2}",
             new Object[] {object, object.getClass().getName(), CarritoCompras.class.getName()});
     return null;
   }
 }