XmlNode.SelectNodes Method (String)

Selects a list of nodes matching the XPath expression.

Namespace: System.Xml
Assembly: System.Xml (in system.xml.dll)

public XmlNodeList SelectNodes (
	string xpath
)
public XmlNodeList SelectNodes (
	String xpath
)
public function SelectNodes (
	xpath : String
) : XmlNodeList
Not applicable.

Parameters

xpath

The XPath expression.

Return Value

An XmlNodeList containing a collection of nodes matching the XPath query. The XmlNodeList should not be expected to be connected "live" to the XML document. That is, changes that appear in the XML document may not appear in the XmlNodeList, and vice versa.

Exception typeCondition

XPathException

The XPath expression contains a prefix.

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.

NoteNote:

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.

NoteNote:

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>&apos;Emma&apos;</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 following example changes the price on all books by Jane Austen.

using System;
using System.IO;
using System.Xml;

public class Sample {

  public static void Main() {

    XmlDocument doc = new XmlDocument();
    doc.Load("booksort.xml");

    XmlNodeList nodeList;
    XmlNode root = doc.DocumentElement;

    nodeList=root.SelectNodes("descendant::book[author/last-name='Austen']");
 
    //Change the price on the books.
    foreach (XmlNode book in nodeList)
    {
      book.LastChild.InnerText="15.95";
    }

    Console.WriteLine("Display the modified XML document....");
    doc.Save(Console.Out);
    
  }
}

import System.*;
import System.IO.*;
import System.Xml.*;

public class Sample
{
    public static void main(String[] args)
    {
        XmlDocument doc = new XmlDocument();
        doc.Load("booksort.xml");

        XmlNodeList nodeList;
        XmlNode root = doc.get_DocumentElement();

        nodeList = 
            root.SelectNodes("descendant::book[author/last-name='Austen']");

        //Change the price on the books.
        for (int iCtr = 0; iCtr < nodeList.get_Count(); iCtr++) {
            XmlNode book = nodeList.Item(iCtr);
            book.get_LastChild().set_InnerText("15.95");
        }
        Console.WriteLine("Display the modified XML document....");
        doc.Save(Console.get_Out());
    } //main 
} //Sample

The example uses the file, booksort.xml, as input.


<?xml version="1.0"?>
<!-- A fragment of a book store inventory database -->
<bookstore xmlns:bk="urn:samples">
  <book genre="novel" publicationdate="1997" bk:ISBN="1-861001-57-8">
    <title>Pride And Prejudice</title>
    <author>
      <first-name>Jane</first-name>
      <last-name>Austen</last-name>
    </author>
    <price>24.95</price>
  </book>
  <book genre="novel" publicationdate="1992" bk:ISBN="1-861002-30-1">
    <title>The Handmaid's Tale</title>
    <author>
      <first-name>Margaret</first-name>
      <last-name>Atwood</last-name>
    </author>
    <price>29.95</price>
  </book>
  <book genre="novel" publicationdate="1991" bk:ISBN="1-861001-57-6">
    <title>Emma</title>
    <author>
      <first-name>Jane</first-name>
      <last-name>Austen</last-name>
    </author>
    <price>19.95</price>
  </book>
  <book genre="novel" publicationdate="1982" bk:ISBN="1-861001-45-3">
    <title>Sense and Sensibility</title>
    <author>
      <first-name>Jane</first-name>
      <last-name>Austen</last-name>
    </author>
    <price>19.95</price>
  </book>
</bookstore>

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0

XNA Framework

Supported in: 1.0

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