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XPathNavigator in Transformations

  • Artigo

The XPathNavigator class provides read-only random access to data and is designed for use as an input to Extensible Stylesheet Language for Transformations (XSLT). It is implemented on the XPathDocument, XmlDataDocument, and XmlDocument. The XPathNavigator is based upon the World Wide Web Consortium (W3C) Data Model as described in section 5 of the XML Path Language (XPath) recommendation.

The XPathNavigator defines a cursor model over any store and provides fast, read-only XPath queries over any data store. The XPathNavigator is also the class to use for iterating over result tree fragments.

The API enables you to get information from the current node in the store and move to connected nodes. The XPathNavigator is a cursor style model that performs traversal over a store using a set of Move methods. The XPathNavigator is always positioned on a node. Any Move method that fails leaves the XPathNavigator unchanged.

The XPathNavigator is the class to use for iterating over result tree fragments. The following code sample creates a result tree fragment within a style sheet by calling the function with the parameter, fragment, which contains XML.

test.xsl

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"  
                xmlns:msxsl ="urn:schemas-microsoft-com:xslt"  
                xmlns:user="https://www.adventure-works.com"  
                version="1.0">  
  
<xsl:variable name="fragment">  
    <authorlist>  
       <author>Joe</author>  
    </authorlist>  
</xsl:variable>  
  
<msxsl:script language="C#" implements-prefix="user">  
<![CDATA[  
   string NodeFragment(XPathNavigator nav)  
   {  
      if (nav.HasChildren)  
        return nav.Value;  
      else  
        return "";  
   }  
]]>  
</msxsl:script>  
  
<xsl:template match="/">  
     <xsl:value-of select="user:NodeFragment($fragment)"/>  
</xsl:template>  
  
</xsl:stylesheet>

test.xml

<root>Some text</root>

The following code uses the test.xsl style sheet and test.xml input data.

Imports System  
Imports System.IO  
Imports System.Xml  
Imports System.Xml.Xsl  
Imports System.Xml.XPath  
Imports System.Text  
Public Class sample  
  
    Public Shared Sub Main()  
        Dim xslt As New XslTransform()  
        xslt.Load("test.xsl")  
  
        Dim xd As New XPathDocument("test.xml")  
  
        Dim strmTemp = New FileStream("out.xml", FileMode.Create, FileAccess.ReadWrite)  
        xslt.Transform(xd, Nothing, strmTemp, Nothing)  
    End Sub 'Main  
End Class 'sample  

using System;  
using System.IO;  
using System.Xml;  
using System.Xml.Xsl;  
using System.Xml.XPath;  
using System.Text;  
  
public class sample  
{  
    public static void Main()  
    {  
        XslTransform xslt = new XslTransform();  
        xslt.Load("test.xsl");  
  
        XPathDocument xd = new XPathDocument("test.xml");  
  
        Stream strmTemp = new FileStream("out.xml", FileMode.Create, FileAccess.ReadWrite);  
        xslt.Transform(xd, null, strmTemp, null);  
    }  
}

Output

The result of the transformation is found in the file out.xml:

<?xml version="1.0" encoding="utf-8"?>Joe

See also