c# - Consuming a REST XML web service

Question

I'm trying to consume the following web service http://ipinfodb.com/ip_location_api.php this web service returns an xml response, the code below gets the XML response, but somehow when phasing the values from the XML response it does not work.

What is wrong with my code?

using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.IO;
using System.Net;
using System.Xml;

namespace ConsoleApplication3
{
class Program
{
    static void Main(string[] args)
    {
        HttpWebRequest request = null;
        HttpWebResponse response = null;
        String Xml;

        // Create the web request  
        request = WebRequest.Create("http://api.ipinfodb.com/v2/ip_query.php?key=<yourkey>&ip=74.125.45.100&timezone=true") as HttpWebRequest;

        // Get response  
        using (response = request.GetResponse() as HttpWebResponse)
        {
            // Get the response stream  
            StreamReader reader = new StreamReader(response.GetResponseStream());

            Xml = reader.ReadToEnd();


        }
        // Console xml output  
        Console.WriteLine(Xml); //see if we get the xml response, (YES we do)

        Console.ReadLine();
            string _currentField = "";
            StringReader _sr = new StringReader(Xml);
            XmlTextReader _xtr = new XmlTextReader(_sr);
            _xtr.XmlResolver = null;
            _xtr.WhitespaceHandling = WhitespaceHandling.None;

            // get the root node
            _xtr.Read();

            if ((_xtr.NodeType == XmlNodeType.Element) && (_xtr.Name == "Response"))
            {
                while (_xtr.Read())
                {
                    if ((_xtr.NodeType == XmlNodeType.Element) && (!_xtr.IsEmptyElement))
                    {
                        _currentField = _xtr.Name;
                        _xtr.Read();
                        if (_xtr.NodeType == XmlNodeType.Text)
                        {
                            switch (_currentField)
                            {
                                case "Status":
                                    Console.WriteLine(_xtr.Value); //we print to console for testing purposes, normally assign it to a variable here!
                                    break;
                                case "CountryCode":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "CountryName":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "RegionCode":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "RegionName":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "City":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "ZipPostalCode":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "Latitude":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "Longitude":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "Gmtoffset":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "Dstoffset":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "TimezoneName":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "Isdst":
                                    Console.WriteLine(_xtr.Value);
                                    break;
                                case "Ip":
                                    Console.WriteLine(_xtr.Value);
                                    break;

                                default:
                                    // unknown field
                                    throw new Exception("Unknown field in response.");
                            }
                        }
                    }
                }
            }
            Console.ReadLine();
    }
}

}

EDIT: this is the XML response returned

  <?xml version="1.0" encoding="UTF-8" ?> 
- <Response>
  <Status>OK</Status> 
  <CountryCode>US</CountryCode> 
  <CountryName>United States</CountryName> 
  <RegionCode>06</RegionCode> 
  <RegionName>California</RegionName> 
  <City>Mountain View</City> 
  <ZipPostalCode>94043</ZipPostalCode> 
  <Latitude>37.4192</Latitude> 
  <Longitude>-122.057</Longitude> 
  <Gmtoffset>-28800</Gmtoffset> 
  <Dstoffset>0</Dstoffset> 
  <TimezoneName>America/Los_Angeles</TimezoneName> 
  <Isdst>0</Isdst> 
  <Ip>74.125.45.100</Ip> 
  </Response>

Answer 1

My solution would be:

• run the xsd.exe utility on your result XML twice to convert it to a XSD (first step) and a C# class (second step) - this would give you a C# class Response

• next, you can easily deserialize the response into an instance of that class:

  HttpWebRequest request = WebRequest.Create("http://api.ipinfodb.com/v2/ip_query.php?key=--yourkey--&ip=74.125.45.100&timezone=true") as HttpWebRequest;
  
  XmlSerializer ser = new XmlSerializer(typeof(Response));
  
  WebResponse response = request.GetResponse();
  var result = ser.Deserialize(response.GetResponseStream());
  

  and now your result would contain an instance of Response, with all the elements as nice fields in your object.

Read more about xsd.exe on its MSDN doc page.