Whim

Slash Post Posted to Blog. Ornery XSLT Question...

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Original Post

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Driving me a bit crazy.

Is the use of the [1] predicate really required?

I'm finding when I remove it, I'm still getting same (correct?) results.

Seems like the 'select' attribute on a key() function's returned node-set is giving me the same thing whether I explicitly indicate I want the first one '[1]' or if I don't explictly do that. (It even seemed to return same results when I explicitly asked for [2] second node. Hmmm. (See final example below.))

Is that the nature of a 'select' attribute on a node-set, to get the first one in node-set anyway? (Hmmmm.)

I expect in the end I'm wrong about all this, and I want to believe my textbook(s)!, yet, I've not been able (yet?) to demonstrate to myself the difference.

[Please note: I do note the explanation worked through in Beginning XSLT on pages 384-385 (TVGuide8.xsl and TVGuide9.xsl), regarding getting "only one" of the elements (<Series> elements in her example). But that still doesn't address what I'm bringing up here (see "Third Example" below).]

Please somebody show me. :^)

Thanks!
(Details below.)
William Reilly

Jeni Tennison's Beginning XSLT book Code Download:
http://jenitennison.com/xslt/5946.zip

FIRST EXAMPLE (of 3)
"Apply-Templates"

Beginning XSLT, p. 386 ff.
=== TVGuide10.xsl ======
<xsl:template match="TVGuide">
<xsl:apply-templates
select="Channel/Program
[generate-id() =
generate-id(key('programsByHour',
substring(Start, 12, 2))[1])]" />

=== Same File, My Edit to Remove '[1]'======
<xsl:template match="TVGuide">
<xsl:apply-templates
select="Channel/Program
[generate-id() =
generate-id(key('programsByHour',
substring(Start, 12, 2)))]" />

=== FileCompare the Two Outputs ("no diff") ======
C:\XSLT-Beginning\Chapter10>fc XSLOutput_10.html XSLOutput_10_no1.html
Comparing files XSLOutput_10.html and XSLOUTPUT_10_NO1.HTML
FC: no differences encountered
=========

SECOND EXAMPLE (of 3)
"For-Each"

http://cscie153.dce.harvard.edu/lecture_notes/7/sl ide14.html

http://cscie153.dce.harvard.edu/lecture_notes/7/ex amples3/group3.xsl
=== group3.xsl ======
<xsl:template name="members_by_state">
<xsl:for-each select="/ushousemembers/member
[generate-id() = generate-id(
key('membersbystate',state)[1]
)
]">
=========

=== Same File, My Edit to Remove '[1]' ======
<xsl:template name="members_by_state">
<xsl:for-each select="/ushousemembers/member
[generate-id() = generate-id(
key('membersbystate',state)
)
]">
==========

=== Unix "diff" on the Two Outputs ("no diff") ===
======
$ diff out_group.html out_group_no1.html
$
=========

THIRD EXAMPLE (of 3)
"xsl:if"

Beginning XSLT, p. 385
=== TVGuide9.xsl ======
<xsl:key name="programsBySeries" match="Program" use="Series" />

<xsl:template match="Program/Series" mode="EpisodeList">
<xsl:variable name="episodes" select="key('programsBySeries', .)" />
<xsl:variable name="firstEpisode" select="$episodes[1]" />
<xsl:if test="generate-id() =
****************************************
generate-id($firstEpisode)">
****************************************
<div>
<h3><a name="{.}" id="{.}"><xsl:value-of select="." /></a></h3>
<h4>Episodes</h4>
<ul>
<xsl:for-each select="$episodes">
===============================

=== Same File, My Edit to Change $firstEpisode to $episodes ========
<xsl:key name="programsBySeries" match="Program" use="Series" />

<xsl:template match="Program/Series" mode="EpisodeList">
<xsl:variable name="episodes" select="key('programsBySeries', .)" />
<xsl:variable name="firstEpisode" select="$episodes[1]" />
<xsl:if test="generate-id() =
****************************************
generate-id($episodes)">
****************************************
<div>
<h3><a name="{.}" id="{.}"><xsl:value-of select="." /></a></h3>
<h4>Episodes</h4>
<ul>
<xsl:for-each select="$episodes">
===========================

=== FileCompare the Two Outputs ("no diff") ======
C:\XSLT-Beginning\5946\Chapter10>fc XSLOutput_09_firstepisode.html XSLOutput_09_
episodes.html
Comparing files XSLOutput_09_firstepisode.html and XSLOUTPUT_09_EPISODES.HTML
FC: no differences encountered
===================================

"Extra Credit" Example ;^)
Same as Third Example, but One Small Edit:
Tried _Second_ Episode '[2]' vs. First.
(Still No Diff!)
=== TVGuide9.xsl ======
<xsl:key name="programsBySeries" match="Program" use="Series" />

<xsl:template match="Program/Series" mode="EpisodeList">
<xsl:variable name="episodes" select="key('programsBySeries', .)" />
<xsl:variable name="secondEpisode" select="$episodes[2]" />
<xsl:if test="generate-id() =
****************************************
generate-id($secondEpisode)">
****************************************
<div>
<h3><a name="{.}" id="{.}"><xsl:value-of select="." /></a></h3>
<h4>Episodes</h4>
<ul>
<xsl:for-each select="$episodes">
===============================

=== FileCompare the Two Outputs ("no diff") ======
C:\XSLT-Beginning\5946\Chapter10>fc XSLOutput_09_secondepisode.html XSLOutput_09
_episodes.html
Comparing files XSLOutput_09_secondepisode.html and XSLOUTPUT_09_EPISODES.HTML
FC: no differences encountered
===================================</ul>< /div></ul></div></ul></div >

Posted by William in category: Web at November 7, 2003 05:05 PM