5.1 - Decision making using <xsl:if>

XML Document 
<?xml version="1.0" encoding="ISO-8859-1"?>
<?xml-stylesheet type="text/xsl" href="iliad05_1.xsl"?>

<document>

<header>
     <title>Iliad</title>
     <book>1.</book>
     <verses>1-7</verses>
     <translator>Lance Jenott</translator>
     <date>
          <month>April</month>
          <year>2004</year>
     </date>
</header>

<poem>
     <line num="1">Sing, oh goddess, about the wrath of <name status="mortal">Achilles</name> son of <name status="mortal">Peleus</name>,</line>
     <line num="2">the accursed wrath which cast a myriad of pain upon the <name status="mortal">Achaeans</name></line>
     <line num="3">and sent forth many noble souls of heroes to <name status="divine">Hades</name>,</line>
     <line num="4">making them prey for dogs and all birds.</line>
     <line num="5">The will of <name status="divine">Zeus</name> was fulfilled,</line>
     <line num="6">when, in fact, the two men first parted ways in strife,</line>
     <line num="7">the son of <name status="mortal">Atreus</name>, ruler of men, and god-like <name status="mortal">Achilles</name>.</line>
</poem>

</document>
Each of the <name> tags in this example contains a status attribute whose value in this example is either set to "mortal" or "divine". Attributes may be any information which the document owner wishes to provide.


XSLT script: iliad05_1.xsl 
<xsl:stylesheet version = '1.0' xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>

<xsl:template match="/">

<table border="1" cellpadding="3">
	<th>Name of Character</th>
	<th>Line #</th>
	<xsl:for-each select="document/poem/line/name">
	<xsl:if test="@status = 'divine'">
		<tr></tr>
		<td>
			<xsl:value-of select="current()"/>	
		</td>
		<td>
			<xsl:value-of select="../@num"/>
		</td>
	</xsl:if>
	</xsl:for-each>
</table>

</xsl:template>

</xsl:stylesheet>
This script generates a table similar to the one in example 4, but here the <xsl:if test="@status = 'divine'"> command is employed in order to only show those names which have a status attribute set to "divine".

*Note that the text-string being tested is always set in single quotes ('divine') within the double quotes of the <xsl:if> command's test= attribute.


RESULTS of iliad05.xsl
Name of Character Line #
Hades3
Zeus5
Only names of divine characters are displayed.


5.2 - Decision making with <xsl:choose> <xsl:when> <xsl:otherwise>

XSLT script: iliad5_2.xsl 
<xsl:stylesheet version = '1.0' xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>

<xsl:template match="/">

<table border="1" cellpadding="3">
	<th>Name of Character</th>
	<th>Line #</th>
	<xsl:for-each select="document/poem/line/name">
	<xsl:choose>
		<xsl:when test="@status = 'divine'">
			<tr></tr>
			<td>
				<font color="purple"> <xsl:value-of select="current()"/> </font>
			</td>
			<td>
				<xsl:value-of select="../@num"/>
			</td>
		</xsl:when>
		<xsl:otherwise>
			<tr></tr>
			<td>
				<font color="black"> <xsl:value-of select="current()"/> </font>
			</td>
			<td>
				<xsl:value-of select="../@num"/>
			</td>
		</xsl:otherwise>
	</xsl:choose>
	</xsl:for-each>
</table>

</xsl:template>

</xsl:stylesheet>
Similar to <xsl:if>, the <xsl:choose> <xsl:when> and <xsl:otherwise> commands can be used to make decisions in order to deal with various scenarios in different ways. As with <xsl:if>, each scenario is specified in the test= attribute of the <xsl:when> command. The <xsl:otherwise> command deals with cases where none of the <xsl:when> scenarios match the test.

In this example, when any <name> tag has a status attribute set to "divine" the browser is told to display the text in purple; otherwise it is told to display the text in black.


RESULTS of iliad5_2.xsl
Name of Character Line #
Achilles1
Achaeans2
Hades3
Zeus5
Atreus7
Achilles7
All names are displayed along with the line number on which they are found. Names of divine characters are displayed in purple.