从页面读取XML响应

Question

I am using C# & ASP.net to perform a POST to a webpage. How can I read the XML response in order to know if my submission had errors or was a success?

This is what I have tried, but it will only return a success/fail message, it will not show me the actual xml returned from the page.

private void Perform()
{
    this.lblResult.Text = string.Empty;
    Dictionary<string, string> dictFormValues = new Dictionary<string, string>();
    string connectionString = null;
    SqlConnection cnn;
    SqlCommand cmd;
    StringBuilder sql = new StringBuilder();
    SqlDataReader reader;
    string email = string.Empty;
    connectionString = "Data Source=server;Initial Catalog=db;User ID=;Password=";
    sql.Append("select TOP 1 maexst ");
    sql.Append("from redbone.redlight.dbo.maxima ");

    cnn = new SqlConnection(connectionString);
    try
    {
        cnn.Open();
        cmd = new SqlCommand(sql.ToString(), cnn);
        reader = cmd.ExecuteReader();
        while (reader.Read()) { dictFormValues.Add("maexst", reader.GetValue(0).ToString()); }
        reader.Close();
        cmd.Dispose();
        cnn.Close();
    }
    catch (Exception ex) { Response.Write(ex.Message.ToString()); }
    string strIpAddress = System.Web.HttpContext.Current.Request.UserHostAddress;
    string strPageTitle = this.Title;
    string strPageURL = System.Web.HttpContext.Current.Request.Url.AbsoluteUri;
    string strError = "";
    bool blnRet = false;
    blnRet = Post(dictFormValues, strPageTitle, strPageURL, ref strError);
    if (blnRet == true)
    {
        this.lblResult.Text = "It was good!";
    }
    else { this.lblResult.Text = strError + ": Error Occured"; }
}

public bool blnRet(Dictionary<string, string> dictFormValues, string strPageTitle, string strPageURL, ref string strMessage)
{
    string strEndpointURL = string.Format("http://testtest12test123.aspx");

    System.Web.Script.Serialization.JavaScriptSerializer json = new System.Web.Script.Serialization.JavaScriptSerializer();
    string strPostData = "";
    foreach (var d in dictFormValues) { strPostData += d.Key + "=" + Server.UrlEncode(d.Value) + "&"; }
    strPostData += "hs_context=";
    System.Net.HttpWebRequest r = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(strEndpointURL);
    r.Method = "POST";
    r.Accept = "application/json";
    r.ContentType = "application/x-www-form-urlencoded";
    r.ContentLength = strPostData.Length;
    r.KeepAlive = false;
    using (System.IO.StreamWriter sw = new System.IO.StreamWriter(r.GetRequestStream()))
    {
        try { sw.Write(strPostData); }
        catch (Exception ex)
        {
            strMessage = ex.Message;
            return false;
        }
    }
    return true; 
}

EDIT

SUCCESS RESPONSE

<?xml version="1.0" encoding="utf-8" ?>
<result>
   <success>1</success>
   <postid>12345</postid>
   <errors/>
</result>

FAIL RESPONSE

<?xml version="1.0" encoding="utf-8" ?>
<result>
   <success>0</success>
   <postid/>
   <errors>
      <error>Error Listed Here</error>
      <error>Error 2 Listed Here</error>
      <error>Error 3 Listed Here</error>
   </errors>
</result>

Answer 1

Try:

var request = WebRequest.Create("http://some.website/") as HttpWebRequest; 
var response = request.GetResponse();

Stream receiveStream = response.GetResponseStream();
StreamReader readStream = new StreamReader(receiveStream, Encoding.UTF8);

var result =  readStream.ReadToEnd();

That will put the content of the page in result

What to do next depends on what the response actually is... From there you could use:

• XmlDocument.LoadXml
• XDocument.Parse
• XElement.Parse

Or perhaps something like the HTML Agility Pack will let you parse the response.

---

Example using XElement

using System.Xml.Linq;
using System.Linq;
using System.Xml;

var xml = System.Xml.Linq.XElement.Parse(result);
if (xml.Elements("success").FirstOrDefault().Value == "1")
{
   // Process Success
   Console.WriteLine("All Worked!");
}
else
{
   var errors = xml.Elements("errors");
   foreach (var error in errors.Elements("error"))
   {
     // read error messages
     Console.WriteLine(error.Value);
   }
}

( Runnable Fiddle )

There's probably a simpler way of parsing the XElement , but that should give you the idea.