Unpivot xml doc based on attributes
Question
I have a simple xml document that looks like the following snippet. I need to write a XSLT transform that basically 'unpivots' this document based on some of the attributes.
<?xml version="1.0" encoding="utf-8" ?>
<root xmlns:z="foo">
<z:row A="1" X="2" Y="n1" Z="500"/>
<z:row A="2" X="5" Y="n2" Z="1500"/>
</root>
This is what I expect the output to be -
<?xml version="1.0" encoding="utf-8" ?>
<root xmlns:z="foo">
<z:row A="1" X="2" />
<z:row A="1" Y="n1" />
<z:row A="1" Z="500"/>
<z:row A="2" X="5" />
<z:row A="2" Y="n2"/>
<z:row A="2" Z="1500"/>
</root>
Appreciate your help.
Solution
<xsl:template match="row">
<row A="{$A}" X="{$X}" />
<row A="{$A}" Y="{$Y}" />
<row A="{$A}" Z="{$Z}" />
</xsl:template>
Plus obvious boilerplate.
OTHER TIPS
Here's the full stylesheet you need (since the namespaces are important):
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:z="foo">
<xsl:template match="root">
<root>
<xsl:apply-templates />
</root>
</xsl:template>
<xsl:template match="z:row">
<xsl:variable name="A" select="@A" />
<xsl:for-each select="@*[local-name() != 'A']">
<z:row A="{$A}">
<xsl:attribute name="{local-name()}">
<xsl:value-of select="." />
</xsl:attribute>
</z:row>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
I much prefer using literal result elements (eg <z:row>
) rather than <xsl:element>
and attribute value templates (those {}
s in attribute values) rather than <xsl:attribute>
where possible as it makes the code shorter and makes it easier to see the structure of the result document that you're generating. Others prefer <xsl:element>
and <xsl:attribute>
because then everything is an XSLT instruction.
If you're using XSLT 2.0, there are a couple of syntactic niceties that help, namely the except
operator in XPath and the ability to use a select
attribute directly on <xsl:attribute>
:
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
exclude-result-prefixes="xs"
xmlns:z="foo">
<xsl:template match="root">
<root>
<xsl:apply-templates />
</root>
</xsl:template>
<xsl:template match="z:row">
<xsl:variable name="A" as="xs:string" select="@A" />
<xsl:for-each select="@* except @A">
<z:row A="{$A}">
<xsl:attribute name="{local-name()}" select="." />
</z:row>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
This is more complex but also more generic:
<xsl:template match="z:row">
<xsl:variable name="attr" select="@A"/>
<xsl:for-each select="@*[(local-name() != 'A')]">
<xsl:element name="z:row">
<xsl:copy-of select="$attr"/>
<xsl:attribute name="{name()}"><xsl:value-of select="."/></xsl:attribute>
</xsl:element>
</xsl:for-each>
</xsl:template>
Here is a bit of a brute force way:
<xsl:template match="z:row">
<xsl:element name="z:row">
<xsl:attribute name="A">
<xsl:value-of select="@A"/>
</xsl:attribute>
<xsl:attribute name="X">
<xsl:value-of select="@X"/>
</xsl:attribute>
</xsl:element>
<xsl:element name="z:row">
<xsl:attribute name="A">
<xsl:value-of select="@A"/>
</xsl:attribute>
<xsl:attribute name="Y">
<xsl:value-of select="@Y"/>
</xsl:attribute>
</xsl:element>
<xsl:element name="z:row">
<xsl:attribute name="A">
<xsl:value-of select="@A"/>
</xsl:attribute>
<xsl:attribute name="Z">
<xsl:value-of select="@Z"/>
</xsl:attribute>
</xsl:element>
</xsl:template>
<xsl:template match="@* | node()">
<xsl:copy>
<xsl:apply-templates select="@* | node()"/>
</xsl:copy>
</xsl:template>