How to set Default values Dynamically in unbound Fields??

Hi guys 

Here I need default values in unbound fields and 

I have tried  below scenarios both are not getting output could plz have look

 [PXUnboundDefault(typeof(Search<CSAttributeDetail.description,
        Where<CSAttributeDetail.valueID,
            Equal<Current<LocationExt.usrSuperMarket>>>>))]

AND

 protected void Location_UsrSuperMarketDescription_FieldDefaulting(PXCache cache, PXFieldDefaultingEventArgs e)
        {

            var row = (Location)e.Row;
            LocationExt line = new LocationExt();

           
            CSAttributeDetail Description2 = (CSAttributeDetail)e.Row;
            if (line.UsrSuperMarket != null)
            {
                line.UsrSuperMarketDescription = Description2.Description;

            }

        }