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Re: [xsl] Preceding-Sibling Axes in Context node.

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Hi Viral,

At 10:35 AM 4/21/2004, you wrote:

I have a question about preceding-sibling.

Okay.

I have following XML

<root>

<record id="1" city="Carbondale" state="IL"/>
<record id="2" city="Columbia" state="MO"/>
<record id="3" city="Bloomington" state="IL"/>
<record id="4" city="St. Louis" state="MO"/>
<record id="5" city="Chicago" state="IL"/>

</root>

And I have following XSL:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:fo="http://www.w3.org/1999/XSL/Format">
<xsl:template match="/">
        <table>
                <xsl:apply-templates match="//root/record">
                        <xsl:sort select="@state"/>
                        <xsl:sort select="@city"/>
                </xsl:apply-templates>
        </table>
</xsl:template>

<xsl:template match="record">
        <xsl:if test="not ( (preceding-sibling::*/@state) = @state )">
                <!-- Some logic that will print out the create a new table
row (tr) and print out the state name....-->
        </xsl:if>
        <td><xsl:value-of select="@city"/></td>
</xsl:template>

</xsl:stylesheet>

What I want is an output where it would to create one table row per state
and list all of its city in the same row but a different <td>.  In my root
template I am sorting the document by state when I do apply templates.  In
the "record" template, I do when I do "preceding-sibling::*/@state" it would
bring me back the state attribute of the preceding sibling in the acutal xml
document and not in the current context.

Correct, except for one thing: preceding-sibling::*/@state will bring back the @state attributes on *all* preceding siblings of your context node. To get the immediately preceding sibling only, use preceding-sibling::*[1]/@state.

So for example if I just did apply-templates sorted by state and city, xsl
should process my nodes in the order below and I have also printed out the
"preceding-sibling" value that my xsl is giving me for each node and the
"preceding-sibling" value that I would expect.:

IL, Bloomington
        -XSL's preceding-sibling: MO, Columbia
        -Preceding-Sibling value that I would like: none
IL, Carbondale
        -XSL's preceding-sibling: none
        -Preceding-Sibling value that I would like: IL, Bloomington
IL, Chicago
        -XSL's preceding-sibling: MO, St. Louis
        -Preceding-Sibling value that I would like: IL, Carbondale
MO, Columbia
        -XSL's preceding-sibling: IL, Carbondale
        -Preceding-Sibling value that I would like: IL, Chicago
MO, St. Louis
        -XSL's preceding-sibling: IL, Bloomington
        -Preceding-Sibling value that I would like: MO, Columbia

What would I need to do to achieve the preceding-sibling value that I want?
Is it even possible?  I already tried using <xsl:key> but that didnt work
either.  If you want me to explain my question then let me know.

I hesitate to say it's not possible, but it's certainly not practical in XSLT 1.0. The best approaches to getting access to the sorted order are: (1) process in two passes with two different stylesheets (first sort, then remove duplicates); (2) process in two passes with a node-set() extension function to turn the result-tree-fragment representing your sorted order into a node set you can process (then the axis will work the way you want); (3) do the same in XSLT 2.0, where no node-set() extension function is needed.

But I'm not convinced you actually need to do this. For de-duplication purposes (making sure each state, or for that matter each city, is processed only once), access to the pre-sorted order will work fine, won't it?

Cheers,
Wendell

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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
Mulberry Technologies, Inc.                http://www.mulberrytech.com
17 West Jefferson Street                    Direct Phone: 301/315-9635
Suite 207                                          Phone: 301/315-9631
Rockville, MD  20850                                 Fax: 301/315-8285
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