Check Data is available or not using C#

private void GetDataFromJSON()
{
    ServicePointManager.Expect100Continue = true;
    ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;

    string strToken = Authenticate.Auth(string.Empty, string.Empty);
    string strrequesturl = $"http://210.255.200.204:804/api/Voucher/GetVoucherByDate?Date_From={txt_SearchByDateFrom.Text}&Date_To={txt_SearchByDateTo.Text}";
    string data = CommonFacade.ExecuteGET(strrequesturl, strToken);

    string json = data;

    gv_Details.DataSource = JsonConvert.DeserializeObject<DataTable>(json);
    DataTable dt = gv_Details.DataSource as DataTable;
    gv_Details.DataBind();
    gv_Details.Visible = true;
    if (dt.Rows.Count > 0)
    {
        btnPrintAll.Visible = true;
        btn_ExportExcel.Visible = true;
        lblTotal.Visible = true;
        lbl_ErrorMsg.Visible = false;
        gv_Details.FooterRow.Cells[7].HorizontalAlign = HorizontalAlign.Center;
        gv_Details.FooterRow.Cells[7].Text = Convert.ToDecimal(dt.Compute("Sum(Amount)", "")).ToString("N2");
        lblTotalRecords.Text = "" + (gv_Details.DataSource as DataTable).Rows.Count;
    }
    else
    {
        btnPrintAll.Visible = false;
        btn_ExportExcel.Visible = false;
        lbl_ErrorMsg.Visible = true;
        lbl_ErrorMsg.Text = "البيانات غير متوفرة.";
    }
}