XSLT

XSLT stands for Extensible Stylesheet Language Transformations.

Links

• https://www.w3.org/TR/xslt
• http://www.w3schools.com/xsl/
• http://xmlsoft.org/XSLT/xslt.html

Gnome library

exslt (extensions)

• http://exslt.org/

Extensions supported in libxml (xsltproc processor)

Overview

Currently there are two versions of the XSLT standards: XSLT 1.0 and XSLT 2.0.

XSLT 1.0

On linux, the standard XSLT 1.0 processor is xsltproc (from package xsltproc, libxml2 library).

In XSLT 1.0, most functions come from XSLT extensions (like http://exslt.org/).

XSLT 2.0

• On linux, the standard XSLT 2.0 processor is saxonb-xslt (from package libsaxonb-java).
• XSLT 2.0 introduces XQuery, XPath 2.0, and XSLT functions (with prefix fn:). See here for a detailed list of features.

Extensions

From w3.org [1]:

• The element extension mechanism allows namespaces to be designated as extension namespaces. When a namespace is designated as an extension namespace and an element with a name from that namespace occurs in a template, then the element is treated as an instruction rather than as a literal result element.

Extensions available in the XSLT processor

Using xsltproc (package xsltproc [2], we can get the list of built-in extensions with:

xsltproc --dumpextensions 
# Registered XSLT Extensions
# --------------------------
# Registered Extension Functions:
# {http://exslt.org/math}atan2
# {http://exslt.org/strings}align
# ...

exslt.org/crypto

• "Hidden" extensions that provides basic crypto functions (apparently from patch [3], introduced in July 5 2004 [4])
• See also [5]
• CAUTION — These extensions are not available if using a custom implementation of Python like Anaconda

xsltproc --dumpextensions|grep crypto
# {http://exslt.org/crypto}rc4_decrypt
# {http://exslt.org/crypto}md4
# {http://exslt.org/crypto}sha1
# {http://exslt.org/crypto}md5
# {http://exslt.org/crypto}rc4_encrypt

Example of use:

<xsl:template match="rootnode">
<xsl:value-of select="crypto:md5('ahahah')"/>
</xsl:template>

Quick reference

Minimal stylesheet

<?xml version="1.0"?>
<xsl:stylesheet version="1.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

</xsl:stylesheet>

This is the minimal stylesheet. Another solution is to use an xsl:transform element, which is a synonym to xsl:stylesheet [6].

<?xml version="1.0"?>
<books>
  <book>
    <title>XML in a Nutshell</title>
    <editor>O'Reilly</editor>
  </book>
  <book>
    <title>XSL in a Nutshell</title>
    <editor>O'Reilly</editor>
  </book>
</book>

When applied to the example XML file above (with xsltproc minimal.xsl example.xml), the minimal stylesheet produces this result:

<?xml version="1.0"?>

  
    XML in a Nutshell
    O'Reilly
  
  
    XSL in a Nutshell
    O'Reilly

The result is not empty. This is because by default XSLT has a default template for text node that simply copy the content of the node without transform.

xsl:attribute

Input	Output
<link site="www.stackoverflow.com"/>	<a href="http://www.stackoverflow.com">Click here</a>

Use

<xsl:template match="link">
    <a>
        <xsl:attribute name="href">
            <xsl:text>http://</xsl:text><xsl:value-of select="@site"/>
        </xsl:attribute>
        <xsl:text>Link</xsl:text>
    </a>
</xsl:template>

Or shorter using curly braces {...} [7]:

<xsl:template match="link">
    <a href="http://{@site}">Click here</a>
</xsl:template>

Also for:

• Using variables (like in <a href="http://{$varName}">Click here</a>)

Tips

Output tags like <?fileVersion 4.0.0 ?>

Use a xsl:text tag with attribute disable-output-escaping="yes": [8]:

<xsl:template match="/">
<xsl:text disable-output-escaping="yes">&lt;?fileVersion 4.0.0?&gt;</xsl:text>
</xsl:template>

This will produce:

<?fileVersion 4.0.0?>

Generate a random UID

<xsl:stylesheet
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:data="http://exslt.org/dates-and-times"
    xmlns:math="http://exslt.org/math"
    extension-element-prefixes="date math"
    version='1.0'>
<!-- .... -->
<xsl:variable name="noncels" select="floor(math:random()*800)+100"/>
<xsl:variable name="noncems" select="data:seconds(date:date-time())-date:seconds('1970-01-01T00:00:00')"/>
<!-- .... -->
<xsl:value-of select="concat($noncems,noncels+0)"/>
</xsl:stylesheet>

Beautify / indent an XML file

Use the identity transform: [9]

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
    <xsl:output method="xml"  encoding="UTF-8" indent="yes" />

    <xsl:template match="@*|node()">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>
</xsl:transform>

Examples

Simple <xsl:template>

XSLT file <?xml version='1.0' encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version='1.0'> <xsl:output method="text" indent="no" encoding="UTF-8"/> <xsl:param name="PARAM"/> <xsl:template match="project"> <xsl:text/>This template will replace 'project' by a simple <xsl:value-of select="$PARAM"/><xsl:text/> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="myname"/> </project> Processed with xsltproc -param PARAM "'text'" style.xsl source output This template will replace 'project' by a simple text

Spaces and CR

XSLT file <?xml version='1.0' encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version='1.0'> <xsl:output method="text" indent="no" encoding="UTF-8"/> <xsl:param name="WORLD"/> <xsl:template match="project"> <xsl:text>CR/spaces are preserved... inside 'xsl:text'.</xsl:text> <xsl:text> But spaces/CR between two tags are deleted.</xsl:text> Except if ... it contains non-blanks. <xsl:text/>So better use empty text tags<xsl:text/> <xsl:text/> to eat spaces/CR, while still using ... xslt <xsl:value-of select="$PARAM"/><xsl:text/> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="myname"/> </project> Processed with xsltproc -param PARAM "'parameters.'" style.xsl source output CR/spaces are preserved... inside 'xsl:text'. But spaces/CR between two tags are deleted. Except if ... it contains non-blanks. So better use empty text tags to eat spaces/CR, while still using ... xslt parameters.

Using entities

XSLT file <?xml version='1.0' encoding="UTF-8"?> <!DOCTYPE xsl:stylesheet [ <!ENTITY cr '<xsl:text xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> </xsl:text>'> <!ENTITY space '<xsl:text xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> </xsl:text>'> <!ENTITY param '<xsl:value-of xmlns:xsl="http://www.w3.org/1999/XSL/Transform" select="$PARAM"/>'> <!ENTITY entity '<xsl:value-of xmlns:xsl="http://www.w3.org/1999/XSL/Transform" select="$ENTITY"/>'> ]> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version='1.0'> <xsl:output method="text" indent="no" encoding="UTF-8"/> <xsl:template match="project"> <xsl:text/>Use entities for special characters like<xsl:text/> <xsl:text/>&cr;&cr;<xsl:text/> carriage return <xsl:text/>&cr;&cr;<xsl:text/> <xsl:text/>or "<xsl:text/>&space;&space;&param;&space;&space;<xsl:text/> <xsl:text/>" where normal "<xsl:text/> <xsl:text/> &param; <xsl:text/>" or <xsl:text/> <xsl:text/>carriage return<xsl:text/> <xsl:text/> <xsl:text/> does not work. Using &entity; is also shorter than using 'xsl:value-of' tags. </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="myname"/> </project> Processed with xsltproc -param PARAM "'space'" -param ENTITY "'entities'" style.xsl source output Use entities for special characters like carriage return or " space " where normal "space" or carriage return does not work. Using entities is also shorter than using 'xsl:value-of' tags.

Using template parameters

XSLT file <?xml version='1.0' encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version='1.0'> <xsl:output method="text" indent="no" encoding="UTF-8"/> <xsl:template match="project"> <xsl:text/>Calling template by matching, passing a string: <xsl:apply-templates select="target"> <xsl:with-param name="PARAM" select="'a string'"/> </xsl:apply-templates> Calling template by matching, passing a GLOBALPARAM: <xsl:apply-templates select="target"> <xsl:with-param name="PARAM" select="$GLOBALPARAM"/> </xsl:apply-templates> Calling template by name <xsl:call-template name="named"> <xsl:with-param name="PARAM" select="'a string'"/> </xsl:call-template> </xsl:template> <xsl:template match="target"> <xsl:param name="PARAM"/> <xsl:text/>parameter is <xsl:value-of select="$PARAM"/><xsl:text/> </xsl:template> <xsl:template name="named"> <xsl:param name="PARAM"/> <xsl:text/>parameter is <xsl:value-of select="$PARAM"/><xsl:text/> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="myname"/> </project> Processed with xsltproc -param GLOBALPARAM "'global param'" style.xsl source output Calling template by matching, passing a string: parameter is a string Calling template by matching, passing a GLOBALPARAM: parameter is global param Calling template by name parameter is a string

Simple <xsl-apply-templates> and .

XSLT file <?xml version='1.0' encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version='1.0'> <xsl:output method="text" indent="no" encoding="UTF-8"/> <xsl:template match="project"> <xsl:apply-templates select="target/*"/> </xsl:template> <xsl:template match="content"> <xsl:text/>dot is '<xsl:value-of select="."/>', <xsl:text/> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="target1"> <content>content1</content> <content>content2</content> <content>content3</content> </target> </project> Processed with xsltproc style.xsl source output dot is 'content1', dot is 'content2', dot is 'content3',

Example of <xsl:for-each>

XSLT file <?xml version='1.0' encoding="UTF-8"?> <!DOCTYPE xsl:stylesheet [ <!ENTITY name '<xsl:value-of xmlns:xsl="http://www.w3.org/1999/XSL/Transform" select="@name"/>'> ]> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version='1.0'> <xsl:output method="text" indent="no" encoding="UTF-8"/> <xsl:template match="project"> <xsl:text/>Simple for-each loop: <xsl:for-each select="target/*"><xsl:text/>dot is '<xsl:value-of select="."/>', </xsl:for-each> For-each loop with select condition: <xsl:for-each select="target/content[@id='second']">&name;, </xsl:for-each> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="target1"> <content id='first' name="only">content1</content> <content id='second' name="double">content2</content> <content id='third' name="last">content3</content> </target> </project> Processed with xsltproc style.xsl source output Simple for-each loop: dot is 'content1', dot is 'content2', dot is 'content3', For-each loop with select condition: double,

Example of <xsl:choose>

XSLT file <?xml version='1.0' encoding="UTF-8"?> <!DOCTYPE xsl:stylesheet [ <!ENTITY name '<xsl:value-of xmlns:xsl="http://www.w3.org/1999/XSL/Transform" select="@name"/>'> ]> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version='1.0'> <xsl:output method="text" indent="no" encoding="UTF-8"/> <xsl:template match="project"> <xsl:apply-templates select="target/*"/> </xsl:template> <xsl:template match="target/*"> <xsl:text/><xsl:variable name="TGTTYPE"> <xsl:choose> <xsl:when test="@type='small'"> <xsl:text/><xsl:value-of select="small"/><xsl:text/> </xsl:when> <xsl:otherwise> <xsl:text/><xsl:value-of select="big"/><xsl:text/> </xsl:otherwise> </xsl:choose> </xsl:variable><xsl:text/> <xsl:text/>We have <xsl:value-of select="$TGTTYPE"/> for <xsl:value-of select="@type"/>. </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="target1"> <content type='small'><small>content1</small><big>CONTENT1</big></content> <content type='big'><small>content2</small><big>CONTENT2</big></content> <content type='small'><small>content3</small><big>CONTENT3</big></content> </target> </project> Processed with xsltproc style.xsl source output We have content1 for small. We have CONTENT2 for big. We have content3 for small.

Template with match rule and dynamic entity

XSLT file <?xml version='1.0' encoding="UTF-8"?> <!DOCTYPE xsl:stylesheet [ <!ENTITY name '<xsl:value-of xmlns:xsl="http://www.w3.org/1999/XSL/Transform" select="@name"/>'> ]> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version='1.0'> <xsl:output method="text" indent="no" encoding="UTF-8"/> <xsl:template match="project/target/*"> <xsl:value-of select="@type"/> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="target1"> <content type='small'><small>content1</small><big>CONTENT1</big></content> <content type='big'><small>content2</small><big>CONTENT2</big></content> <content type='small'><small>content3</small><big>CONTENT3</big></content> </target> </project> Processed with xsltproc style.xsl source output small big small

More complex apply-templates, with dynamic entities

XSLT file <?xml version='1.0' encoding="UTF-8"?> <!DOCTYPE xsl:stylesheet [ <!ENTITY name '<xsl:value-of xmlns:xsl="http://www.w3.org/1999/XSL/Transform" select="@name"/>'> ]> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version='1.0'> <xsl:output method="text" indent="no" encoding="UTF-8"/> <xsl:template match="project"> <xsl:apply-templates select="target/*"/> </xsl:template> <xsl:template match="project/target/*"> <xsl:value-of select="@type"/> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="target1"> <content type='small'><small>content1</small><big>CONTENT1</big></content> <content type='big'><small>content2</small><big>CONTENT2</big></content> <content type='small'><small>content3</small><big>CONTENT3</big></content> </target> </project> Processed with xsltproc style.xsl source output smallbigsmall

Using namespace

XSLT file <?xml version='1.0' encoding="UTF-8"?> <!DOCTYPE xsl:stylesheet [ <!ENTITY name '<xsl:value-of xmlns:xsl="http://www.w3.org/1999/XSL/Transform" select="@name"/>'> ]> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:ns="http://your.server.org/your/xsl/url/MYNS" exclude-result-prefixes="xsl ns" version='1.0'> <xsl:output method="text" indent="no" encoding="UTF-8"/> <xsl:template match="ns:project"> <xsl:apply-templates select="ns:target/*"/> </xsl:template> <xsl:template match="ns:project/ns:target/*"> <xsl:if test="@type='small'">SMALL </xsl:if> <xsl:if test="@type='big'">BIG </xsl:if> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <ns:project xmlns:ns="http://your.server.org/your/xsl/url/MYNS" name="myproject"> <ns:target name="target1"> <ns:content type='small'>content1</ns:content> <ns:content type='big'>content2</ns:content> <ns:content type='small'>content3</ns:content> </ns:target> </ns:project> Processed with xsltproc style.xsl source output SMALL BIG SMALL

Example of expressions

XSLT file <?xml version='1.0' encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:math="http://exslt.org/math" extension-element-prefixes="math" version='1.0'> <xsl:output method="xml" indent="yes" encoding="UTF-8"/> <xsl:template match="project"> <xsl:apply-templates select="target/*"/> </xsl:template> <xsl:template match="project/target/*"> <p> <msg>dot is current tag content, here '.' is '<xsl:value-of select="."/>'</msg> <msg attr="{.}">Use braces {...} in attributes</msg> <msg random="unique.{floor(math:random()*2147483647)}">{...} can be any expression</msg> </p> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="target1"> <content type='small'>content1</content> <content type='big'>content2</content> <content type='small'>content3</content> </target> </project> Processed with xsltproc style.xsl source output <?xml version="1.0" encoding="UTF-8"?> <p> <msg>dot is current tag content, here '.' is 'content1'</msg> <msg attr="content1">Use braces {...} in attributes</msg> <msg random="unique.799522789">{...} can be any expression</msg> </p><p> <msg>dot is current tag content, here '.' is 'content2'</msg> <msg attr="content2">Use braces {...} in attributes</msg> <msg random="unique.90206728">{...} can be any expression</msg> </p><p> <msg>dot is current tag content, here '.' is 'content3'</msg> <msg attr="content3">Use braces {...} in attributes</msg> <msg random="unique.2005052793">{...} can be any expression</msg> </p>

Generate custom XML tags

XSLT file <?xml version='1.0' encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:math="http://exslt.org/math" extension-element-prefixes="math" version='1.0'> <xsl:output method="xml" indent="yes" encoding="UTF-8"/> <xsl:template match="project"> <xsl:text disable-output-escaping="yes">&lt;?fileVersion 4.0.0?&gt;</xsl:text><cproject id="my project"/> <p>Use 'disable-output-escaping' to generate xml tags.</p> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target name="target1"> <content type='small'>content1</content> <content type='big'>content2</content> <content type='small'>content3</content> </target> </project> Processed with xsltproc style.xsl source output <?xml version="1.0" encoding="UTF-8"?> <?fileVersion 4.0.0?><cproject id="my project"/><p>Use 'disable-output-escaping' to generate xml tags.</p>

Removing white spaces

XSLT file <?xml version='1.0' encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version='1.0'> <xsl:output method="xml" indent="yes" version="1.0" encoding="UTF-8" standalone="no"/> <xsl:template match="project"> <project> <xsl:apply-templates select="*"/> </project> </xsl:template> <xsl:template match="target"> <cleaned_target><xsl:value-of select="normalize-space(.)"/></cleaned_target> </xsl:template> </xsl:stylesheet> Source file <?xml version="1.0"?> <project name="myproject"> <target>no_space_at_all</target> <target> with_space_around </target> <target>with carriage returns </target> <target>with spaces between the words</target> </project> Processed with xsltproc style.xsl source output <?xml version="1.0" encoding="UTF-8" standalone="no"?> <project> <cleaned_target>no_space_at_all</cleaned_target> <cleaned_target>with_space_around</cleaned_target> <cleaned_target>with carriage returns</cleaned_target> <cleaned_target>with spaces between the words</cleaned_target> </project>

Miscellaneous

• <xsl:param name="MYPARAM"> in <xsl:stylesheet> node declares a global parameter.

After this declaration we can use $MYPARAM to get the value of the parameter. If it is not declared, we can only use $MYPARAM if it is passed as a parameter (e.g. via command line xsltproc -param MYPARAM "'myparamvalu'"), otherwise an error is triggered.