XSLT and XPath function reference in alphabetical order
(Excerpt from “XSLT 2.0 & XPath 2.0” by Frank Bongers, chapter 5, translated from German)
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current-grouping-key
Category:
Context information within a sequence
Origin:
XSLT 2.0
Return value:
An atomic value; the current value of the grouping criterion during the processing of a group formed by xsl:for-each-group.
Call/Arguments:
current-grouping-key()
No arguments.
Purpose of use:
With the help of the current-grouping-key() function, the current value of the grouping criterion on which the group is based can be used during the processing of a group formed by the XSLT instruction xsl:for-each-group. This value is determined by the attributes group-by or group-adjacent of the instruction. The returned value is always an atomic value (a singleton sequence) and never a sequence consisting of several values.
Outside the evaluation context of a xsl:for-each-group instruction, the function always returns the empty sequence.
No current-grouping-key() in XPath patterns:
The current-grouping-key() function is not permitted as a part of XPath patterns. If used in XPath patterns, a static error will occur which makes the processing of the stylesheet impossible.
Example:
(Translated from the German data2type XSLT 2.0 reference, xsl:for-each-group element, example 2)
Source document:
<?xml version="1.0" encoding="UTF-8"?>
<root>
<city country="de">
<name>Berlin</name>
<population>3420786</population>
<surface>891,85</surface>
<community>11000000</community>
<evaluation>5</evaluation>
</city>
<city country="de">
<name>Hamburg</name>
<population>1773218</population>
<surface>755,264</surface>
<community>02000000</community>
<evaluation>4</evaluation>
</city>
<city country="fr">
<name>Paris</name>
<population>2166200</population>
<surface>105,40</surface>
<evaluation>3</evaluation>
</city>
<city country="de">
<name>Ludwigshafen</name>
<population>163777</population>
<surface>77,68</surface>
<evaluation>-3</evaluation>
</city>
</root>
XSLT stylesheet:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
<xsl:template match="root">
<directory>
<xsl:for-each-group select="city" group-by="@country">
<group>
<key>
<xsl:value-of select="current-grouping-key()"></xsl:value-of>
</key>
<xsl:for-each select="current-group()">
<city>
<xsl:value-of select="name"></xsl:value-of>
</city>
</xsl:for-each>
</group>
</xsl:for-each-group>
</directory>
</xsl:template>
</xsl:stylesheet>Result:
<?xml version="1.0" encoding="UTF-8"?>
<directory>
<group>
<key>de</key>
<city>Berlin</city>
<city>Hamburg</city>
<city>Ludwigshafen</city>
</group>
<group>
<key>fr</key>
<city>Paris</city>
</group>
</directory>In this example the cities are grouped by their country codes ("de" or "fr"). The current-grouping-key() function returns the current key value by means of which the grouping was made ("de" or "fr").
Function definition:
XSLT 1.0:
The function is not available.
XSLT 2.0:
current-grouping-key() as xs:anyAtomicType
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