Dear Christian,
XSLT 2.0 has a distinct-values() function, which
is useful for this kind of thing, along with its native grouping constructs.
In XSLT 1.0, it's a fairly standard grouping
problem. Usually we de-duplicate a set of nodes
by determining which members of the set are the
first (in document order) with a given value. In
your case, you have to decide whether the value
you want to check is the code value, or the name
(if they're in a strict one-to-one relation it
doesn't matter, and the value is more convenient).
Keys are a very convenient way to de-duplicate
when your data set is large. You can use brute XPath if not.
So:
<xsl:key name="manure-type-codes" match="gr:ManureTypeCode"
use="."/>
<xsl:key name="manure-type-names" match="gr:ManureTypeName"
use="../gr:ManureTypeCode"/>
<xsl:template match="gr:ManureTypeCode">
<xsl:if test="generate-id() = generate-id(key('manure-type-codes',.)[1])">
<!-- tests true only if the ManureTypeCode is the first with this value,
more or less the equivalent of 'select distinct' -->
<xsl:copy-of select="key('manure-type-names',.)"/>
</xsl:if>
</xsl:template>
If the codes and names are in a one-to-many or
many-to-many relation, we have to think harder.
I hope this helps!
Wendell
At 05:55 PM 6/2/2006, you wrote:
Hi experts,
I've been struggling with a problem for several hours now, and I
cannot find the solution:
I have an XML document with a elements grouped in elements and
ManureTypeCodes and datavalues as siblings.
Then I have - somewhere else - in the document lookup information
(labels) for the codes.
These are grouped in elements of ManureTypeCodes and ManureTypeNames
I want to create a template rule which matches the codes and looks up
the corresponding name and ONLY writes the
ManureTypeName out once! In RDBMS I would use something like select
distinct when selecting the codes, but I dont know what the right
approach is in XSLT.
can someone please help.... on before hand thank you!
my XML:
<eih>
<!-- Codes and data -->
<eih:ManureTypeCollection>
<eih:ManureTypeStructure>
<gr:ManureTypeCode>5</gr:ManureTypeCode>
<gr:ElementIdentifier>N</gr:ElementIdentifier>
<gr:ElementQuantity>17.0</gr:ElementQuantity>
</eih:ManureTypeStructure>
<eih:ManureTypeStructure>
<gr:ManureTypeCode>5</gr:ManureTypeCode>
<gr:ElementIdentifier>P</gr:ElementIdentifier>
<gr:ElementQuantity>0.6</gr:ElementQuantity>
</eih:ManureTypeStructure>
<eih:ManureTypeStructure>
<gr:ManureTypeCode>4</gr:ManureTypeCode>
<gr:ElementIdentifier>N</gr:ElementIdentifier>
<gr:ElementQuantity>17.5</gr:ElementQuantity>
</eih:ManureTypeStructure>
<eih:ManureTypeStructure>
<gr:ManureTypeCode>4</gr:ManureTypeCode>
<gr:ElementIdentifier>P</gr:ElementIdentifier>
<gr:ElementQuantity> 6.3</gr:ElementQuantity>
</eih:ManureTypeStructure>
</eih:ManureTypeCollection>
<!-- look up information for the codes -->
<eih:XImanureTypeCollection>
<eih:XImanureTypeStructure>
<gr:ManureTypeCode>4</gr:ManureTypeCode>
<gr:ManureTypeName>Fast gødning</gr:ManureTypeName>
</eih:XImanureTypeStructure>
<eih:XImanureTypeStructure>
<gr:ManureTypeCode>5</gr:ManureTypeCode>
<gr:ManureTypeName>Ajle</gr:ManureTypeName>
</eih:XImanureTypeStructure>
<eih:XImanureTypeStructure>
</eih:XImanureTypeCollection>
</eih>
best regards,
Christian Rasmussen
Denmark
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