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Apply XSLT Transform to an already transformed XML

Tags:

xslt

All,

I have an XML file which I transform it using an XSLT document to another XML.

Can I define another set of transformations in the same XSLT file to be applied in the result XML of the first transformation?

Thanks,

MK

like image 448
koumides Avatar asked Sep 09 '10 16:09

koumides


1 Answers

Yes.

I. This XSLT 1.0 transformation:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:ext="http://exslt.org/common"
 xmlns:msxsl="urn:schemas-microsoft-com:xslt"
 >
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:variable name="vrtfPass1">
  <xsl:apply-templates/>
 </xsl:variable>

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

 <xsl:template match="node()|@*" mode="pass2">
  <xsl:copy>
   <xsl:apply-templates select="node()|@*" mode="pass2"/>
  </xsl:copy>
 </xsl:template>

 <xsl:template match="num/text()">
  <xsl:value-of select="2*."/>
 </xsl:template>

 <xsl:template match="num/text()" mode="pass2">
  <xsl:value-of select="1+."/>
 </xsl:template>

 <xsl:template match="/">
  <xsl:apply-templates select="ext:node-set($vrtfPass1)/*" mode="pass2"/>
 </xsl:template>
</xsl:stylesheet>

when applied on this XML document:

<t>
 <num>1</num>
 <num>2</num>
 <num>3</num>
 <num>4</num>
 <num>5</num>
</t>

produces:

<t>
    <num>3</num>
    <num>5</num>
    <num>7</num>
    <num>9</num>
    <num>11</num>
</t>

Do note:

  1. Two transformations are actually performed, the second is performed on the result of the first.

  2. The result of the first transformation is the content of the variable $vrtfPass1.

  3. In XSLT 1.0 the type of variables that contain dynamically generated (temporary) XML trees (XML document or XML fragment) is RTF (Result-Tree-Fragment). No XPath operations are possible on an RTF -- it needs to be converted to a regular node-set using the extension function xxx:node-set(), which is provided by the vast majority of XSLT 1.0 processor vendors. In this example exslt:node-set() is used, because EXSLT is implemented by many different vendors.

  4. The second transformation is applied on the result of the first: <xsl:apply-templates select="ext:node-set($vrtfPass1)/*" mode="pass2"/> . A separate mode is used in order to cleanly separate the code of the two transformations.

  5. The first transformation multiplies each num/text() by 2. The second transformation increments each num/text(). The result is 2*.+1

II. This XSLT 2.0 transformation:

<xsl:stylesheet version="2.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xs="http://www.w3.org/2001/XMLSchema" >
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:variable name="vPass1">
  <xsl:apply-templates mode="pass1"/>
 </xsl:variable>

 <xsl:template match="node()|@*" mode="pass1">
  <xsl:copy>
   <xsl:apply-templates select="node()|@*" mode="pass1"/>
  </xsl:copy>
 </xsl:template>

 <xsl:template match="node()|@*" mode="pass2">
  <xsl:copy>
   <xsl:apply-templates select="node()|@*" mode="pass2"/>
  </xsl:copy>
 </xsl:template>

 <xsl:template match="num/text()" mode="pass1">
  <xsl:value-of select="2*xs:integer(.)"/>
 </xsl:template>

 <xsl:template match="num/text()" mode="pass2">
  <xsl:value-of select="1+."/>
 </xsl:template>

 <xsl:template match="/">
  <xsl:apply-templates select="$vPass1"  mode="pass2"/>
 </xsl:template>
</xsl:stylesheet>

when applied on the same XML document, produces the same wanted and correct result.

Do note: In XSLT 2.0/XPath 2.0 the RTF type has been abolished. No xxx:node-set() extension function is needed.

like image 160
Dimitre Novatchev Avatar answered Oct 07 '22 02:10

Dimitre Novatchev