RE: Need some help with an XPath

[Adam van den Hoven] 

> I have a node set that looks something like:
> 
> <branch>
>     <service servId="Service 1" /> 
>     <service servId="Service 3" /> 
>     <service servId="Service 4" />
> </branch>
[snipped]
> 
> Now what I want is a set of all the service elements that do 
> not appear in ALL the branch Elements. In this case I'm hoping for 
> 
>     <service servId="Service 3" />
>     <service servId="Service 2" />
>     <service servId="Service 3" />
> 

You cannot compare each servId with the set of unique servId values,
since there would always be a match.  So you have to check each unique
value in turn to see if it is present in the branch.
Here is a fairly simple way to do this.  Yes, it does use a key - to
create the set of unique servId values - and yes, it does use
xsl:for-each - to check each of those unique values.

First the result, then the stylsheet -

=========== result ============
<results>
   <branch>missing: Service 2</branch>
   <branch>missing: Service 3</branch>
   <branch>missing: Service 2</branch>
</results>

=============== Stylesheet =============

<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output encoding='iso-8859-1'/>

<xsl:key name='services' match='service' use='@servId'/>

<xsl:variable name='services' select='/root/branch/service'/>
<xsl:variable name='unique-services'
	select='$services[generate-id(.) =
generate-id(key("services",@servId))]'/>
<xsl:variable name='unique-service-ids'
select='$unique-services/@servId'/>

<xsl:template match="/root">
<results>
	<xsl:apply-templates select='branch'/>
</results>
</xsl:template>


<xsl:template match='branch'>
	<xsl:variable name='servs' select='service/@servId'/>
	<branch>
		<xsl:for-each select='$unique-service-ids'>
			<xsl:if test='not(. = $servs)'>missing:
<xsl:value-of select='.'/></xsl:if>
		</xsl:for-each>
	</branch>
</xsl:template>
</xsl:stylesheet>

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