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

I use the this same API, I load the response XML into an XDocument and parse e.g.

// build URL up at runtime
string apiKey = ConfigurationManager.AppSettings["geoApiKey"];
string url = String.Format(ConfigurationManager.AppSettings["geoApiUrl"], apiKey, ip);

WebRequest request = WebRequest.Create(url);
try
{
    WebResponse response = request.GetResponse();
    using (var sr = new System.IO.StreamReader(response.GetResponseStream()))
    {
        XDocument xmlDoc = new XDocument();
        try
        {
            xmlDoc = XDocument.Parse(sr.ReadToEnd());
            string status = xmlDoc.Root.Element("Status").Value;
            Console.WriteLine("Response status: {0}", status);
            if (status == "OK")
            { 
                // if the status is OK it's normally safe to assume the required elements
                // are there. However, if you want to be safe you can always check the element
                // exists before retrieving the value
                Console.WriteLine(xmlDoc.Root.Element("CountryCode").Value);
                Console.WriteLine(xmlDoc.Root.Element("CountryName").Value);
                ...
            }                
        }
        catch (Exception)
        {
            // handle if necessary
        }   
    }
}
catch (WebException)
{
    // handle if necessary    
}

What you should also do is introduce a custom class e.g. GeoLocationInfo and wrap your code in a function e.g. GetGeoLocation(string ip) then instead of writing the info to the console window you can populate & return an instance of that class.