MSDN Documentation

Overview

Represents an immutable, read-only, in-memory XPath data model instance. The XPathDocument class provides a fast, forward-only, read-only XML data store that can be used for XPath queries. It is optimized for performance when you are querying XML data.

XPathDocument is a read-only representation of an XML document. If you need to modify the XML document, use the XmlDocument class. XPathDocument is an efficient way to query large XML documents.

Syntax

public sealed class XPathDocument

Constructors

Properties

Methods

Remarks

The XPathDocument class implements the IXsltContext interface, which allows it to be used with the XslTransform class for XSLT transformations. It is a memory-efficient representation of XML data, designed for scenarios where read-only access and fast querying are paramount.

When you load an XML document into an XPathDocument, it is converted into an internal, optimized representation that is suitable for XPath data model traversal. This process is typically faster than loading into an XmlDocument, especially for large documents.

The CreateNavigator() method is the primary way to interact with the data within an XPathDocument. The returned XPathNavigator object can be used to select nodes, evaluate XPath expressions, and retrieve node values.

Example

The following example demonstrates how to load an XML document into an XPathDocument and query it using an XPathNavigator.

using System;
using System.Xml;
using System.Xml.XPath;

public class Example
{
    public static void Main(string[] args)
    {
        // Sample XML string
        string xmlString = @@"<books>
            <book id='bk101'>
                <author>Gambardella, Matthew</author>
                <title>XML Developer's Guide</title>
                <genre>Computer</genre>
                <price>44.95</price>
            </book>
            <book id='bk102'>
                <author>Ralls, Kim</author>
                <title>Midnight Rain</title>
                <genre>Fantasy</genre>
                <price>5.95</price>
            </book>
        </books>";

        // Load the XML string into an XPathDocument
        using (XmlReader reader = XmlReader.Create(new StringReader(xmlString)))
        {
            XPathDocument doc = new XPathDocument(reader);

            // Create an XPathNavigator to query the document
            XPathNavigator navigator = doc.CreateNavigator();

            // Select all book titles
            XPathNodeIterator nodes = navigator.Select("/books/book/title/text()");

            Console.WriteLine("Book Titles:");
            while (nodes.MoveNext())
            {
                Console.WriteLine($"- {nodes.Current.Value}");
            }

            // Select books with a price greater than 10
            nodes = navigator.Select("/books/book[price > 10]");

            Console.WriteLine("\nBooks with price > 10:");
            while (nodes.MoveNext())
            {
                Console.WriteLine($"- Title: {nodes.Current.SelectSingleNode("title").Value}, Price: {nodes.Current.SelectSingleNode("price").Value}");
            }
        }
    }
}

Requirements