如何在gridview中将复选框转换为字符串值？

Question

如何在使用asp.net mvc将数据导出到Excel中时，将复选框转换为gridview中的字符串值？

型号：

    public class empViewmodel
    {         
        public int id { get; set; }
        public string name { get; set; }
        public string address { get; set; }
        public bool male{ get; set; }
        public Nullable<int> city_id { get; set; }
    }

控制器：

    public ActionResult export1(emplyeeModel em)
    {
        var grid = new GridView();
        grid.DataSource = e1.getlist(em);
        grid.DataBind();

        Response.ClearContent();
        Response.Buffer = true;
        Response.AddHeader("content-disposition", "attachment; filename=MyExcelFile.xls");
        Response.ContentType = "application/ms-excel";

        Response.Charset = "";
        StringWriter sw = new StringWriter();
        HtmlTextWriter htw = new HtmlTextWriter(sw);

        grid.RenderControl(htw);

        Response.Output.Write(sw.ToString());
        Response.Flush();
        Response.End();

        return View("export");
    }

Getlist方法：

        public List<emplyeeModel> getlist(emplyeeModel e1)
        {
            var tbl =db.emps.ToList();
            List<emplyeeModel> lst = new List<emplyeeModel>();
            foreach (var item in tbl)
            {
                emplyeeModel M1 = new emplyeeModel();
                M1.id = item.id;
                M1.name = item.name;
                M1.address = item.address;
                M1.male= item.gender;

                lst.Add(M1);

            }
            return lst;
        }

在male列中是一个布尔值，它显示一个复选框，但我想显示字符串yes / no（True / False）而不是复选框，同时将数据导出到excel中。