protected void gvSales_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                //
                string datakey = gvSales.DataKeys[e.Row.RowIndex].Values[0].ToString();

                GridView gvDetails = e.Row.FindControl("gvDetails") as GridView;
                gvDetails.DataSource = SalesDetails.GetSalesDetailsByInvno(datakey);
                gvDetails.DataBind();
            }
        }
        private void GetSalesDetailsByInvoice()
        {
            string invno      = Request["invno"];
            var    collection = SalesDetails.GetSalesDetailsByInvno(invno);
            //
            JsonBridge <SalesDetails> datafeed = new JsonBridge <SalesDetails>();

            if (collection.Count != 0)
            {
                datafeed.collection = collection;
                datafeed.Valid      = 1;
            }
            else
            {
                datafeed.collection = collection;
                datafeed.Valid      = 0;
            }
            //
            string output = JsonConvert.SerializeObject(datafeed);

            Response.Write(output);
        }