XSLT evaluate variable whose name is coming from xpath evaluation

Question

Following my previous post : XSLT take first element that can be mapped among list of predefined mappings

Is there a way to evaluate a variable, in a xsl:value-of, whose name is coming from the evaluation of XPATH ?

The original XML :

<sectors type="array">
   <sector>industry</sector>
   <sector>e-commerce</sector>
   <sector>logistique</sector>
<sectors>

This is my XSLT (thanks to https://stackoverflow.com/a/73040079/10767428) :

<xsl:import href="./sector.xslt"/>

<s:sector source="metallurgy" target="$sector_industry_materials" />
<s:sector source="accounting" target="$sector_audit_accounting" />
<s:sector source="logistics" target="$sector_service_logistics" />
<s:sector source="mass-distribution" target="$sector_distribution_mass_retail" />

<xsl:template match="sectors">
    <sectorIdentifier>
        <xsl:variable name="sector" select="sector[. = document('')/*/s:sector/@source][1]"/>
        <xsl:choose>
            <xsl:when test="$sector">
                <xsl:variable name="target" select="document('')/*/s:sector[@source=$sector]/@target"/>
                <xsl:value-of select="$target" />
            </xsl:when>
            <xsl:otherwise>
                <xsl:value-of select="$sector_other"/>
            </xsl:otherwise>
        </xsl:choose>
    </sectorIdentifier>
</xsl:template>

Here, the value of $target are either the strings : $sector_industry_materials, $sector_audit_accounting, $sector_service_logistics, $sector_distribution_mass_retail or $sector_other.

I want those strings to be evaluated against the following other XSLT, from another file, and imported in current file :

sector.xslt :

<?xml version="1.0" ?>
  <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">  
  <xsl:variable name="sector_industry_materials" >401</xsl:variable>
  <xsl:variable name="sector_audit_accounting" >374</xsl:variable>
  <xsl:variable name="sector_service_logistics" >422</xsl:variable>
  <xsl:variable name="sector_distribution_mass_retail" >387</xsl:variable>
  <xsl:variable name="sector_other" >456</xsl:variable>
</xsl:stylesheet>

So the final output, in case the $target value was the string $sector_industry_materials, must be :

<sectorIdentifier>401</sectorIdentifier>

But for now, all I get is :

<sectorIdentifier>$sector_distribution_mass_retail</sectorIdentifier>

The thing is that with $sector_other, which is hard-coded, everything works fine, and I get :

<sectorIdentifier>456</sectorIdentifier>

SO the problem must be that name of the variables are dynamic.

Thank you

Dynamic XPath evaluation exists as an optional feature with xsl:evaluate only in XSLT 3.0 (Saxon 10 HE and later, Saxon 9.8 PE/EE and later, Saxon-JS 2) or as processor specific, proprietary extension in earlier versions. Which XSLT 1.0 processor exactly do you use? — Martin Honnen
– Martin Honnen, Commented Jul 20, 2022 at 14:16
This is very confusing. Could you not eliminate the middleman and map industry directly to 401, accounting to 374 and so on? This map could be hard-coded into your stylesheet or - if you prefer - it could be stored in an external XML document. Such document does not need to be an XSLT stylesheet; in fact, making it so only complicates things. — michael.hor257k
– michael.hor257k, Commented Jul 20, 2022 at 15:47
At first sight this seems to be a very complicated way of achieving something very simple. But you haven't explained what you're trying to achieve, and it's really hard to reverse engineer the requirements from the code. — Michael Kay
– Michael Kay, Commented Jul 21, 2022 at 12:20
@michael.hor257k I agree that this seems complicated, but we need to have this middleware for code generation. But I will check if there is a way to have a direct mapping between metallurgy and 401 in the XML file itself, instead of going through the process of finding first sector_industry_materials. Thank you for your time. — vittorio
– vittorio, Commented Jul 21, 2022 at 13:08
Even with 2 maps, it should be quite simple to find the first sector that has an entry in map A using key('sector', $mapA/key)[1] and then lookup the corresponding value in map B using key('mapB', $foundValue). At no point should there be a need to evaluate a string as an XPath expression. — michael.hor257k
– michael.hor257k, Commented Jul 21, 2022 at 13:47

Mads Hansen · Accepted Answer · 2022-07-20 14:34:50Z

1

You could use the same technique and drill into the imported sector.xslt as an XML doc, selecting the value with XPath:

<xsl:when test="$sector">
  <xsl:variable name="target" select="document('')/*/s:sector[@source=$sector]/@target"/>
  <!-- <xsl:value-of select="$target" /> -->
  <xsl:value-of select="document('sector.xslt')/xsl:stylesheet/xsl:variable[contains($target, @name)]"/>
</xsl:when>

It would be a little more straightforward if you changed the s:sector/@target values not to have $ for variable name references, and just had the value to match the sector.xslt xsl:variable/@name.

answered Jul 20, 2022 at 14:34

Mads Hansen

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1 Comment

vittorio Over a year ago

Thank you, this works as expected. I did not think of using the XSLT sheet as a regular XML file.

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