Pairing Elements XSLT

[bay]

Hi,
I'm trying to write a transformation that takes repeating elements and places them in pairs and in order in the XML output. I want to convert this:

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<Root>

    <heading>Chapter 1</heading>

    <module>

        <para>Para 1</para>

    </module>

    <module>

        <para>Para 2</para>

    </module>

    <module>

        <para>Para 3</para>

    </module>

    <module>

        <para>Para 4</para>

    </module>

    <module>

        <para>Para 5</para>

    </module>

    <heading>Chapter 2</heading>

    <module>

        <para>Para 6</para>

    </module>

    <module>

        <para>Para 7</para>

    </module>

    <module>

        <para>Para 8</para>

    </module>

</Root>

into:

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<Root>

    <heading>Chapter 1</heading>

    <double_module>

        <para>Para 1</para>

         <para>Para 2</para>

    </double_module>

    <double_module>

        <para>Para 3</para>

        <para>Para 4</para>

    </double_module>

    <module>

        <para>Para 5</para>

    </module>

    <heading>Chapter 2</heading>

    <double_module>

        <para>Para 6</para>

        <para>Para 7</para>

    </double_module>

    <module>

        <para>Para 8</para>

    </module>

    <heading>Chapter 3</heading>

</Root>

My current XSLT finds each element and pairs it with its following-sibling but because it processes each node I get a
<double_module><para>Para 1</para><para>Para 2</para></double_module> and a <double_module><para>Para 2</para><para>Para 3</para></double_module>

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<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">

    <xsl:output indent="yes"/>

    <xsl:template match="Root">

        <lesson>

            <xsl:apply-templates/>

        </lesson>

    </xsl:template>

    <xsl:template match="para">

        <xsl:copy-of select="."/>

    </xsl:template>

    <xsl:template match="heading">

        <xsl:copy-of select="."/>

    </xsl:template>

    <xsl:template match="module">      

        <xsl:choose>

            <xsl:when test="following-sibling::*[1][self::module]">                        <double_module>

                    <xsl:apply-templates/>

                    <xsl:apply-templates mode="in-module"

                        select="following-sibling::*[1][self::module]"/>

                </double_module>  

            </xsl:when>

            <xsl:otherwise>

                <module>

                    <xsl:apply-templates/>

                </module>

            </xsl:otherwise>

        </xsl:choose>

    </xsl:template>

    <xsl:template match="module" mode="in-module">

        <xsl:apply-templates/>

    </xsl:template>

</xsl:stylesheet>

Any assistance is greatly appreciated.
Thanks,
Bay

[jkmyoung]

Add this before your other module template:
<xsl:template match="module[position() mod 2 = 0]">
<xsl:apply-templates/>
</xsl:template>

[bay]

Thanks!

I assume you meant:

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<xsl:template match="module[position() mod 2 = 0]"/>

... which just about works.

The problem now is that module 6 (where position() mod 2 = 0)which follows a <chapter> should begin a <double_ module>, but instead is ignored by the above template.

[bay]

Perhaps recursion is required for this?

[george]

Hi,

My approach will be with a positional processing. Match on the Root and apply templates on the first element. For heading and modules that do not have a pair just copy them and process the next sibling. The other modules will have a pair so when we match on one we copy the content of that and the content of the following module inside a double-module element.

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<?xml version="1.0" encoding="UTF-8" ?>

<xsl:stylesheet version="1.0"

    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <xsl:output indent="yes"/>

    <xsl:template match="Root">

        <xsl:copy>

            <xsl:apply-templates select="*[1]"/>

        </xsl:copy>

    </xsl:template>

    <xsl:template

        match="heading|module[following-sibling::*[1][self::heading] or

        not(following-sibling::*)]">

        <xsl:copy-of select="."/>

        <xsl:apply-templates select="following-sibling::*[1]"/>

    </xsl:template>



    <xsl:template match="module">

        <double-module>

            <xsl:copy-of select="./*"/>

            <xsl:copy-of select="following-sibling::*[1]/*"/>

        </double-module>

        <xsl:apply-templates select="following-sibling::*[2]"/>

    </xsl:template>

</xsl:stylesheet>

Best Regards,
George

[bay]

Worked great! Thanks very much.