XmlNode.SelectNodes Method (String)
Selects a list of nodes matching the XPath expression.
Assembly: System.Xml (in System.Xml.dll)
If the XPath expression requires namespace resolution, you must use the SelectNodes overload which takes an XmlNamespaceManager as its argument. The XmlNamespaceManager is used to resolve namespaces.
If the XPath expression does not include a prefix, it is assumed that the namespace URI is the empty namespace. If your XML includes a default namespace, you must still use the XmlNamespaceManager and add a prefix and namespace URI to it; otherwise, you will not get any nodes selected. For more information, see Select Nodes Using XPath Navigation.
A common issue when formulating XPath expressions is how to include a single quote (') or double quote (") in the expression. If you have to search for a value that includes a single quote, you must enclose the string in double quotes. If you need to search for a value that includes a double quote, you must enclose the string in single quotes.
For example, suppose you have the following XML:
<bookstore> <book> <title>'Emma'</title> </book> </bookstore>
The following Visual Basic code selects an element that contains single quotes:
nodeList = root.SelectNodes("//book[contains(title,""'Emma'"")]")
This method is a Microsoft extension to the Document Object Model (DOM).
The XmlNodeList object returned by this method will be valid while the underlying document remains unchanged. If the underlying document changes, unexpected results may be returned (no exception will be thrown).
The following example selects all books where the author's last name is Austen, and then changes the price of those books.
Imports System Imports System.IO Imports System.Xml public class Sample public shared sub Main() 'Create the XmlDocument. Dim doc as XmlDocument = new XmlDocument() doc.Load("booksort.xml") Dim book as XmlNode Dim nodeList as XmlNodeList Dim root as XmlNode = doc.DocumentElement nodeList=root.SelectNodes("descendant::book[author/last-name='Austen']") 'Change the price on the books. for each book in nodeList book.LastChild.InnerText="15.95" next Console.WriteLine("Display the modified XML document....") doc.Save(Console.Out) end sub end class
This example uses the following XML:
Available since 1.1