Yes, that seems like the most elegant solution, since for my purposes an empty
string and a null attribute are synonymous. Thanks!
On Tue, 26 Apr 2016, Martin Honnen martin(_dot_)honnen(_at_)gmx(_dot_)de wrote:
On 26.04.2016 20:39, David Sewell dsewell(_at_)virginia(_dot_)edu wrote:
(Following assumes XSLT 2.0)
I don't use the @group-adjacent form of <xsl:for-each-group> often
enough to be a master of it. I just ran into the problem that an empty
sequence is not allowed as the result of evaluating the group-adjacent
expression. Given data like
<contributor role="author">Joe Jones</contributor>
<contributor role="author">Mary Mitchell</contributor>
<contributor role="editor">Betty Berkeley</contributor>
<contributor role="editor">Peter Parker</contributor>
my first instinct was to use
<xsl:for-each-group select="contributor" group-adjacent="@role">
but I got a run-time error because the @role is not always present in my
data. So I revised to
<xsl:for-each-group select="contributor" group-adjacent="if (@role)
then string(@role) else 'false'">
which give the desired results. But is there a better general strategy,
maybe using boolean false() as the grouping value, and then being sure
to cast current-grouping-key() as a string whenever a string comparison
is needed?
I would be inclined to simply use
group-adjacent="string(@role)"
unless you could have both <el role="">...</el> and <el>...</el> and
would need to distinguish them.
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ROTUNDA, The University of Virginia Press
PO Box 400318, Charlottesville, VA 22904-4314 USA
Email: dsewell(_at_)virginia(_dot_)edu Tel: +1 434 924 9973
Web: http://rotunda.upress.virginia.edu/
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