Question

Given a XmlNode containing the following XML fragment, how do I fill XmlNodeList with book nodes?

XMLNode nodeLibrary contains:

<library>
  <book>
      <title>Three Little Pigs</title>
  </book>
  <book>
      <title>Batman</title>
  </book>
  <address>123 Main St.</address>
  <phone>111-111-1111</phone>
</library>

This should be really easy but I can’t figure it out:

A) Cannot implicitly convert type ‘System.Xml.XmlElement’ to ‘System.Xml.XmlNodeList’:

XmlNodeList books = nodeLibrary[“book”];

I guess the method property shortcut above assumes there’s a SINGLE child named book, not multiple!

B) XmlNode doesn’t have a GetChildren() method:

XmlNodeList books = nodeLibrary.GetChildren(“book”);

C) XmlNode’s ChildNodes property gets ALL children, not just book nodes.

D) I tried using SelectNodes() method but the root is the larger document, not the library fragment in the current XmlNode that was selected from a larger document earlier using SelectNodes.

Any ideas?
Pete

Answer 1

You can use SelectNodes, and in the XPath query pass a ‘.’ to start searching from that node:

public class StackOverflow_6618097
{
    const string XML = @"<buildings>
 <library>
  <book>
   <title>Three Little Pigs</title>
  </book>
  <book>
   <title>Batman</title>
  </book>
  <address>123 Main St.</address>
  <phone>111-111-1111</phone>
  <hidden>
   <book>
    <title>The Hidden Treasure</title>
   </book>
  </hidden>
 </library>
 <bookstore>
  <book>
   <title>Cat in the Hat</title>
  </book>
 </bookstore>
</buildings>";

    public static void Test()
    {
        XmlDocument doc = new XmlDocument();
        doc.LoadXml(XML);
        XmlNode libraryNode = doc.SelectSingleNode("//library");
        XmlNodeList libraryBooks = libraryNode.SelectNodes(".//book");
        Console.WriteLine("Books: {0}", libraryBooks.Count);
        foreach (XmlNode node in libraryBooks)
        {
            Console.WriteLine(node.OuterXml);
        }
    }
}