At 2004-10-06 15:13 -0700, David P. Nesbitt wrote:
I am getting some unexpect results from an XPath
predicate.
Yours is a common mistake made by my students who have looked at XPath
before taking a class.
I am trying to load the unique values of
an element into a variable. The XML file is grouped
by this element. I want to treat the absence of the
element as a value as well (the "null" value if you
will). However, I can't get the XPath predicate to
filter out multiple "null" values.
You are forgetting that "preceding-sibling::" looks at *all* preceding
siblings, not just the closest preceding sibling.
I am including below a data file, stylesheet, expected
output and observed output.
Thank you, that made it easy to modify to illustrate the fix.
If you can see anything
wrong, I would most appreciate your assistance.
Use a predicate "[1]" to talk about the immediately preceding sibling, not
*all* preceding siblings.
I hope this helps.
.................... Ken
p.s. your use of boolean() on a node set is redundant ... the processor is
already converting both operands to boolean when the operator is boolean.
T:\ftemp>type nesbitt.xml
<a>
<b>
<c>123</c>
<d>000</d>
</b>
<b>
<c>123</c>
<d>000</d>
</b>
<b>
<d>000</d>
</b>
<b>
<d>000</d>
</b>
<b>
<c>456</c>
<d>000</d>
</b>
<b>
<c>456</c>
<d>000</d>
</b>
<b>
<c>789</c>
<d>000</d>
</b>
</a>
T:\ftemp>type nesbitt.xsl
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
xmlns:fo="http://www.w3.org/1999/XSL/Format";>
<xsl:output method="text"/>
<xsl:template match="a">
<xsl:variable name="unique-cs"
select="/a/b[(not(preceding-sibling::b) or
(not(c) and preceding-sibling::b[1]/c) or
(c and not(c=preceding-sibling::b[1]/c)))]"/>
<xsl:for-each select="$unique-cs">
<xsl:value-of select="c"/>
<xsl:text>
</xsl:text>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
T:\ftemp>saxon nesbitt.xml nesbitt.xsl
123
456
789
T:\ftemp>
--
Upcoming publicly-subscribed XSL delivery: Helsinki Oct 18-20,2004
World-wide on-site corporate, govt. & user group XML/XSL training.
G. Ken Holman mailto:gkholman(_at_)CraneSoftwrights(_dot_)com
Crane Softwrights Ltd. http://www.CraneSoftwrights.com/s/
Box 266, Kars, Ontario CANADA K0A-2E0 +1(613)489-0999 (F:-0995)
Male Breast Cancer Awareness http://www.CraneSoftwrights.com/s/bc
Legal business disclaimers: http://www.CraneSoftwrights.com/legal