| <xsl:key> | |
| Defines an index against the current document. The element is defined with three attributes: a name, which names this index; a match, an XPath expression that describes the nodes to be indexed; and a use attribute, an XPath expression that defines the property used to create the index. | |
| Category | |
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Top-level element |
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| Required Attributes | |
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| Optional Attributes | |
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None. |
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| Content | |
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None. <xsl:key> is an empty element. |
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| Appears in | |
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<xsl:key> is a top-level element and can only appear as a child of <xsl:stylesheet>. |
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| Defined in | |
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XSLT section 12.2, Keys. |
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| Example | |
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Here is a stylesheet that defines two <xsl:key> relations against an XML document:
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="html" indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:key name="language-index" match="defn" use="@language"/>
<xsl:key name="term-ids" match="term" use="@id"/>
<xsl:param name="targetLanguage"/>
<xsl:template match="/">
<xsl:apply-templates select="glossary"/>
</xsl:template>
<xsl:template match="glossary">
<html>
<head>
<title>
<xsl:text>Glossary Listing: </xsl:text>
<xsl:value-of select="key('language-index',
$targetLanguage)[1]/preceding-sibling::term"/>
<xsl:text> - </xsl:text>
<xsl:value-of select="key('language-index',
$targetLanguage)[last()]/preceding-sibling::term"/>
</title>
</head>
<body>
<h1>
<xsl:text>Glossary Listing: </xsl:text>
<xsl:value-of select="key('language-index',
$targetLanguage)[1]/ancestor::glentry/term"/>
<xsl:text> - </xsl:text>
<xsl:value-of select="key('language-index',
$targetLanguage)[last()]/ancestor::glentry/term"/>
</h1>
<xsl:for-each select="key('language-index', $targetLanguage)">
<xsl:apply-templates select="ancestor::glentry"/>
</xsl:for-each>
</body>
</html>
</xsl:template>
...
</xsl:stylesheet>
For a complete discussion of this stylesheet, illustrating how the <xsl:key> relations are used, see Section 5.2.3 in Chapter 5. |
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