Parsing through XML elements in XmlReader

Hi all,

I'm building an application that needs to run through an XML feed but I'm having a little trouble with getting certain elements.

I'm using the Twitter feed and want to run through all the <item> elements. I can connect fine and get the content from the feed but I can't figure out how to select only the item elements when I'm loopuing through reader.Read();.

Thanks for your help!

From stackoverflow Ross

• The easiest way to do that is to use XPath. Example to follow.

   string xml = @"<?xml version=""1.0"" encoding=""UTF-8""?>
  <rss version=""2.0"">
      <channel>
      <title>Twitter public timeline</title>
      <link>http://twitter.com/public_timeline</link>
      <description>Twitter updates from everyone!</description>
      <language>en-us</language>
      <ttl>40</ttl>
  
      <item>
        <title>yasu_kobayashi: rTwT: @junm : yayaya</title>
        <description>yasu_kobayashi: rTwT: @junm : yayaya</description>
        <pubDate>Tue, 28 Oct 2008 12:04:48 +0000</pubDate>
        <guid>http://twitter.com/yasu_kobayashi/statuses/978829930</guid>
        <link>http://twitter.com/yasu_kobayashi/statuses/978829930</link>
  
      </item><item>
        <title>FreeGroup: WikiFortio - foobar http://tinyurl.com/5gvttf</title>
        <description>FreeGroup: WikiFortio - foobar
        http://tinyurl.com/5gvttf</description>
        <pubDate>Tue, 28 Oct 2008 12:04:47 +0000</pubDate>
        <guid>http://twitter.com/FreeGroup/statuses/978829929</guid>
        <link>http://twitter.com/FreeGroup/statuses/978829929</link>
  
      </item></channel></rss>
          ";
              XPathDocument doc = new XPathDocument(new StringReader(xml));
              XPathNavigator nav = doc.CreateNavigator();
  
              // Compile a standard XPath expression
  
              XPathExpression expr;
              expr = nav.Compile("/rss/channel/item");
              XPathNodeIterator iterator = nav.Select(expr);
  
              // Iterate on the node set
  
              try
              {
                  while (iterator.MoveNext())
                  {
                      XPathNavigator nav2 = iterator.Current.Clone();
                      nav2.MoveToChild("title","");
                      Console.WriteLine(nav2.Value);
                      nav2.MoveToParent();
                      nav2.MoveToChild("pubDate","");
                      Console.WriteLine(nav2.Value);
  
                  }
              }
              catch (Exception ex)
              {
                  Console.WriteLine(ex.Message);
              }
              Console.ReadKey();
  

  And this is jan's approach working

          XmlDocument doc2 = new XmlDocument();
          doc2.LoadXml(xml);
          XmlNode root = doc2.DocumentElement;
  
          foreach (XmlNode item in root.SelectNodes(@"/rss/channel/item"))
          {
              Console.WriteLine(item.SelectSingleNode("title").FirstChild.Value);
              Console.WriteLine(item.SelectSingleNode("pubDate").FirstChild.Value);
          }
  

  From Vinko Vrsalovic

• An alternative:

  // starts as in Vinko Vrsalovic 's answer
  // and not including decent eror handling
  XmlDocument doc = new XmlDocument(new StringReader(xml)); 
  
  foreach (XmlNode item in doc.SelectNodes(@"/rss/channel/item"))
  {
    Console.WriteLine(item.SelectSingleNode("title").Value);
    Console.WriteLine(item.SelectSingleNode("pubDate").Value);
  }
  

  I don't know if this code is slower or bad practice. Please do comment.

  I find it more readable than the other one using Navigator and Iterator.

  Edit: I use an XmlDocument. An XPathDocument as in Vinko Vrsalovic 's answer doesn't support this way of working, but is a lot faster: (MSDN)

  AnthonyWJones : Unless you have a very large stream which makes loading the content into a document undesirable then this would a reasonable approach and a lot more readable than using an XmlReader.

  Vinko Vrsalovic : I like this approach too. But you can't use it with a XPathDocument, you need a XmlNode

  jan : My mistake! I meant XmlDocument. But since I can imagine a Twitter rss feed to become very large, I'd go - in this case - for an implementation using XPathDocument too.
  From jan