private async Task <string> PostValidationData(ValidationData validationData) { logger.LogInformation("validationData:" + validationData.ToString()); var baseAddress = new Uri("https://icinfo.immigration.gov.tw"); var cookieContainer = new CookieContainer(); using (var handler = new HttpClientHandler() { CookieContainer = cookieContainer }) using (var client = new HttpClient(handler) { BaseAddress = baseAddress }) { IList <KeyValuePair <string, string> > nameValueCollection = new List <KeyValuePair <string, string> > { { new KeyValuePair <string, string>("IDNO", validationData.Idno) }, { new KeyValuePair <string, string>("APPROVE_DATE", validationData.ApproveDate) }, { new KeyValuePair <string, string>("END_STAY_PERIOD", validationData.ExpiredDate) }, { new KeyValuePair <string, string>("BARCODE_NO", validationData.BarcodeNo) }, { new KeyValuePair <string, string>("TextBox1", validationData.TextBox1) }, { new KeyValuePair <string, string>("ReNext", validationData.ReNext) }, { new KeyValuePair <string, string>("__VIEWSTATE", validationData.ViewState) }, { new KeyValuePair <string, string>("__VIEWSTATEGENERATOR", validationData.ViewStateGenerator) }, { new KeyValuePair <string, string>("__EVENTVALIDATION", validationData.EventValidation) }, }; cookieContainer.Add(baseAddress, new Cookie("ASP.NET_SessionId", validationData.SessionId)); var res = await client.PostAsync("/NIL_WEB/NFCData.aspx", new FormUrlEncodedContent(nameValueCollection)); var responseHtml = res.Content.ReadAsStringAsync().Result; var docs = new HtmlDocument(); docs.LoadHtml(responseHtml); var result = docs.GetElementbyId("lblResult").InnerText; return(result); } }