reading node from xml file in XMLDocument

Question

i am trying to grab the TopicName how should i go after it and try different combination but somehow i am unable to get TopicName below is my source codee...

XmlDocument xdoc = new XmlDocument();//xml doc used for xml parsing

    xdoc.Load(
        "http://latestpackagingnews.blogspot.com/feeds/posts/default"
        );//loading XML in xml doc

    XmlNodeList xNodelst = xdoc.DocumentElement.SelectNodes("content");//reading node so that we can traverse thorugh the XML

    foreach (XmlNode xNode in xNodelst)//traversing XML 
    {
        //litFeed.Text += "read";
    }

sample xml file

<content type="application/xml">
 <CatalogItems xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="sitename.xsd">
        <CatalogSource Acronym="ABC" OrganizationName="ABC Corporation" />
        <CatalogItem Id="3212" CatalogUrl="urlname">
          <ContentItem xmlns:content="sitename.xsd" TargetUrl="url">
            <content:SelectionSpec ClassList="" ElementList="" />
            <content:Language Value="eng" Scheme="ISO 639-2" />
            <content:Source Acronym="ABC" OrganizationName="ABC Corporation" />
            <content:Topics Scheme="ABC">
              <content:Topic TopicName="Marketing" />
              <content:Topic TopiccName="Coverage" />
            </content:Topics>
          </ContentItem>
        </CatalogItem>
      </CatalogItems>
    </content>

Answer 1

The Topic nodes in your XML are using the content namespace - you need to declare and use the XML namespace in your code, then you can use SelectNodes() to grab the nodes of interest - this worked for me:

XmlNamespaceManager nsmgr = new XmlNamespaceManager(xdoc.NameTable);
nsmgr.AddNamespace("content", "sitename.xsd");

var topicNodes = xdoc.SelectNodes("//content:Topic", nsmgr);

foreach (XmlNode node in topicNodes)
{
    string topic = node.Attributes["TopicName"].Value;
}

Just as a comparison see how easy this would be with Linq to XML:

XDocument xdoc = XDocument.Load("test.xml");
XNamespace ns = "sitename.xsd";
string topic = xdoc.Descendants(ns + "Topic")
                   .Select(x => (string)x.Attribute("TopicName"))
                   .FirstOrDefault();

To get all topics you can replace the last statement with:

var topics = xdoc.Descendants(ns + "Topic")
                 .Select(x => (string)x.Attribute("TopicName"))
                 .ToList();