CIS 97YT - Lecture 8 XPath

Lecture 8 - Testing XPath Expressions

This wasn't very pretty; I was in a burning hurry to get these files online, so I did the first thing that came into my head that worked. Here's the XSLT file for the first two examples.

 1	<?xml version="1.0"?>
 2	<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 3		version="1.0">
 4	
 5	<xsl:output encoding="ISO8859-1" method="text"/>
 6	
 7	<xsl:template match="text()"/>
 8	
 9	<xsl:template match="street-list/street[2]/name[position()=1]">
10		<xsl:for-each select="following-sibling::metro">
11			<xsl:text>Metro: </xsl:text><xsl:value-of select="."/><xsl:text>
12	</xsl:text>
13		</xsl:for-each>
14		<xsl:text>========
15	</xsl:text>
16	
17	
18		<xsl:for-each select="following::metro">
19			<xsl:text>Metro: </xsl:text><xsl:value-of select="."/><xsl:text>
20	</xsl:text>
21		</xsl:for-each>
22		<xsl:text>========
23	</xsl:text>
24
25	</xsl:template>
26	</xsl:stylesheet>

Line 5

This tells XSLT to produce a simple text file rather than an XML or HTML file. While in this case I'm producing a text file just because I don't want to have to fool around with output of nicely-formatted HTML, this example does point out that you can use XSLT to convert an XML file to plain text suitable for emailing or importing into a word processor.

Line 9

This is truly brute force. I set the context node by creating a template that matches the first <name> node within the second <street> node within any <streets> element, of which there's only one, since it's the root element.

Note that I use a shortcut notation to find the second <street> element, and use the full notation for the <name>.

Lines 10-15, Lines 18-23

Now that the context node is established, I do an <xsl:for-each> with the select attribute set to each XPath expression I want to test. Inside the <xsl:for-each> I produce some simple output that lets me know which node was selected. I use <xsl:text> to get control over whitespace. This is especially important since I'm producing a text file, not an HTML file, where the extra whitespace would be ignored.

A tool for showing XPath in action, XPath Visualizer, is available at http://www.vbxml.com/xpathvisualizer/default.asp. It is for Windows only.