public void ExportarExcel(DataTable dt, string fileName)
        {
            Response.ClearContent();
            Response.ContentEncoding = System.Text.Encoding.Default;
            Response.AddHeader("content-disposition", "attachment; filename=" + fileName + ".csv");
            Response.ContentType = "text/csv";

            string tab = "";
            int indice = 0;
            foreach (DataColumn dc in dt.Columns)
            {
                if (indice > 0)
                {
                    Response.Write(tab + dc.ColumnName);
                    tab = ";";
                }
                indice++;
            }
            Response.Write("\n");

            int i;
            foreach (DataRow dr in dt.Rows)
            {
                tab = "";
                for (i = 0; i < dt.Columns.Count; i++)
                {
                    if (i > 0)
                    {
                        Response.Write(tab + dr[i].ToString());
                        tab = ";";
                    }
                }
                Response.Write("\n");
            }
            Response.End();
        }

        public static DataTable ToDataTable<T>(List<T> data)
        {
            PropertyDescriptorCollection props =
                TypeDescriptor.GetProperties(typeof(T));
            DataTable table = new DataTable();
            for (int i = 0; i < props.Count; i++)
            {
                PropertyDescriptor prop = props[i];
                table.Columns.Add(prop.Name, prop.PropertyType);
            }
            object[] values = new object[props.Count];
            foreach (T item in data)
            {
                for (int i = 0; i < values.Length; i++)
                {
                    values[i] = props[i].GetValue(item);
                }
                table.Rows.Add(values);
            }
            return table;
        }



        [HttpPost]
        [Authorize(Roles = "Admin")]
        [MultipleButton(Name = "action", Argument = "Exportar")]
        public void Exportar()
        {
            var dados = db.RF_DiasUteis.ToList();
            var dt = ToDataTable(dados);
            string fileName = "DiasUteis";
            ExportarExcel(dt, fileName);
        }