public ActionResult Submit()
        {
            PhanHoiController ctr = new PhanHoiController();
             PhanHoi obj = new PhanHoi();
            //get post value
                string tendaydu = TextLibrary.ToString(Request["front_contact_author"]);
                string sdt = TextLibrary.ToString(Request["front_contact_phone"]);
                string email = TextLibrary.ToString(Request["front_contact_email"]);
                string tieude = TextLibrary.ToString(Request["front_contact_tieude"]);
                string noidung = TextLibrary.ToString(Request["front_contact_text"]);
                string captcha = TextLibrary.ToString(Request["front_contact_captcha"]);
            //pass to obj
                if (this._khachhang != null)
                {
                    obj.khachhang = ctr._db.ds_khachhang.Where(x => x.id == this._khachhang.id).FirstOrDefault();
                }
                else
                {
                    obj.nguoigui_email = email;
                    obj.nguoigui_sdt = sdt;
                    obj.nguoigui_ten = tendaydu;
                }
                obj.tieude = tieude;
                obj.noidung = noidung;
             //validate
                List<string> validate = ctr.validate(obj);
                //xét captcha
                if (!this.get_captcha_string().ToLower().Equals(captcha.ToLower()))
                {
                    validate.Add("captcha_fail");
                }
            //Check ok
                if (validate.Count == 0)
                {
                    ctr.add(obj);
                    validate.Add("success");
                }

                ViewBag.State = validate;
                ViewBag.phanhoi = obj;
                return View("Index");
        }