XSLT Gouping, for-each and implicated loop. How to eliminate duplicates? - xslt

Question

Hope find a guru's help to figure out the next problem.
I have two xml files. Firts one here (text.xml):
<text>
<ref>Author1, Title1, Date1</ref>
<ref>Author75, Title75, Date2</ref>
<ref>Author2, Title2, Date2</ref>
<ref>Author3, Title3, Date3</ref>
<text>
And the second one like this (list.xml):
<list>
<bibl xml:id="1"><author>Author1</author><date>Date1</date></bibl>
<bibl xml:id="2"><author>Author2</author><date>Date2</date></bibl>
<bibl xml:id="3"><author>Author3</author><date>Date3</date></bibl>
</list>
I want to query text.xml and check against list.xml to add #xml:id (from list.xml) to <ref> (from text.xml) wich contain same Author and Date. If not, then just copy original <ref>.
So I want to obtain:
<ref xml:id="1">Author1, Title1, Date1</ref>
<ref>Author75, Title75, Date2</ref>
<ref xml:id="2>Author2, Title2, Date2</ref>
etc.
My XSLT identify well all correpondence:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="ref">
<xsl:variable name="ref" select="."/>
<xsl:for-each select="document('list.xml')//bibl">
<xsl:variable name="bibl" select="."/>
<xsl:variable name="author" select="author"/>
<xsl:variable name="date" select="date"/>
<xsl:choose>
<xsl:when test="contains($ref, $author) and contains($ref, $date)">
<ref>
<xsl:attribute name="xml:id">
<xsl:value-of select="$bibl/#xml:id"/>
</xsl:attribute>
<xsl:value-of select="$ref"/>
</ref>
</xsl:when>
<xsl:otherwise>
<xsl:copy-of select="$ref"/>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
But, then there aren't correpondence it's not just copy right <ref>, but copy all <ref> the number of time I have <bibl> nodes in the second file.
So problem is in <xsl:otherwise><xsl:copy-of select="$ref"/></xsl:otherwise>.
Any ideas how I can obtain only this distinct value I need? I know it's must be very simple actually and I try key, generate-id, for-each-group, distinct-values, but can't figure it out.

Answer 1

The problem is that you are creating a ref element for each iteration of the for-each loop whether there is a match or not.
What you need to do in this case is create the ref element outside of the for-each and then only create the id attribute for the matching element inside the loop
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="ref">
<xsl:variable name="ref" select="."/>
<ref>
<xsl:apply-templates select="#* "/>
<xsl:for-each select="document('list.xml')//bibl">
<xsl:variable name="bibl" select="."/>
<xsl:variable name="author" select="author"/>
<xsl:variable name="date" select="date"/>
<xsl:choose>
<xsl:when test="contains($ref, $author) and contains($ref, $date)">
<xsl:attribute name="xml:id">
<xsl:value-of select="$bibl/#xml:id"/>
</xsl:attribute>
</xsl:when>
</xsl:choose>
</xsl:for-each>
<xsl:apply-templates select="node()"/>
</ref>
</xsl:template>
</xsl:stylesheet>
When applied to your sample XML, the following is output
<text>
<ref xml:id="1">Author1, Title1, Date1</ref>
<ref>Author75, Title75, Date2</ref>
<ref xml:id="2">Author2, Title2, Date2</ref>
<ref xml:id="3">Author3, Title3, Date3</ref>
</text>
However, your current method is not very efficient, as for each ref element you are iterating over all bibl elements. Another approach would be to extract the author and date from the ref elements, and then look up the bibl element directly
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="ref">
<xsl:variable name="author" select="normalize-space(substring-before(., ','))"/>
<xsl:variable name="date" select="normalize-space(substring-after(substring-after(., ','), ','))"/>
<ref>
<xsl:apply-templates select="#* "/>
<xsl:apply-templates select="document('list.xml')//bibl[author=$author][date=$date]"/>
<xsl:apply-templates select="node()"/>
</ref>
</xsl:template>
<xsl:template match="bibl">
<xsl:attribute name="xml:id">
<xsl:value-of select="#xml:id"/>
</xsl:attribute>
</xsl:template>
</xsl:stylesheet>
This should also give the same results.

Answer 2

EDIT:
humm...too much focus on xsl syntax, i should have seen that earlier...
you have an implicated outer loop over each ref and an inner loop over each bibl. You generate one element for every bibl for every ref regardless of match or no match.
So, instead of the xsl:otherwise you need a check after the for-each loop to see if there was no match and do the copy-of if neccessary.
Not sure how to do the check, though..maybe using position() and count() of the generated <ref>s, sorry...don't have any more time to think about this right now.
not really an explanation, but a workaround:
<xsl:otherwise>
<ref>
<xsl:value-of select="$ref"/>
</ref>
</xsl:otherwise>
My guess is that the problem lies in $ref, which is not a xpath expression at that moment (if i remember xsl-t correctly)