protected void GridView1_SelectedIndexChanged(object sender, CommandEventArgs e)
    {
        try
        {
            GridView gv = GridView1;
            int Id = -1;
            if (int.TryParse(e.CommandArgument.ToString(), out Id))
            {
                switch (e.CommandName)
                {
                    case "O":
                        var fl = from fn in ldc.DocumentLists where fn.id == Convert.ToInt32(gv.Rows[Id].Cells[0].Text) select fn;
                        foreach (DocumentList dc in fl)
                        {
                            if (dc.access == "public")
                            { Response.Redirect("~/DocumentContent.aspx?id=" + gv.Rows[Id].Cells[0].Text);}
                            else
                            {
                                if (!string.IsNullOrEmpty(User.Identity.Name))
                                {
                                    if (User.IsInRole(dc.access))
                                    { Response.Redirect("~/DocumentContent.aspx?id=" + gv.Rows[Id].Cells[0].Text); }
                                    else {Response.Redirect("~/Access.aspx"); }
                                }
                            }
                        }
                        break;
                    case "P":
                        if (!string.IsNullOrEmpty(User.Identity.Name))
                        {
                            if (User.IsInRole("print"))
                            { Response.Redirect("~/DocumentPrint.aspx?id=" + gv.Rows[Id].Cells[0].Text); }
                            else { Response.Redirect("~/Access.aspx"); }
                        }
                        else { Response.Redirect("~/Access.aspx"); }
                        break;
                    case "L":
                        if (User.IsInRole("download"))
                        {
                            var fld = from fnd in ldc.DocumentLists where fnd.id == Convert.ToInt32(gv.Rows[Id].Cells[0].Text) select fnd;
                            foreach (DocumentList dcd in fld)
                            {
                                if (!string.IsNullOrEmpty(dcd.file))
                                { Response.Redirect("~/Files/Documents/" + dcd.file); }
                            }
                        }
                        else { Response.Redirect("~/Access.aspx"); }
                        break;
                }
            }
        }
        catch { Response.Redirect("~/Error.aspx"); }
    }

int Id = -1;
if (int.TryParse(e.CommandArgument.ToString(), out Id))
{

 Convert.ToInt32(gv.Rows[Id].Cells[0].Text)

protected void GridView1_SelectedIndexChanged(object sender, GridViewCommandEventArgs e)
    {
        try
        {
            if (e.CommandName == "Print")
            {
                int index = Convert.ToInt32(e.CommandArgument);
                GridViewRow row = GridView1.Rows[index];
                Response.Redirect(string.Format("PrintDocument.aspx?id={0}", Server.HtmlDecode(row.Cells[0].Text));

            }
//......
        }
        catch { }
       
    }