Re: [xsl] match by arbitrary number of criteria

["Andrew Welch" <andrew.j.welch@xxxxxxxxx>]

On 6/4/07, John Horner <Horner.John@xxxxxxxxxx> wrote:
> I've got XML roughly like this:
>
> <items>
>         <item>
>                 <name>foo</name>
>                 <subjects>
>                         <subject>Science</subject>
>                         <subject>Politics</subject>
>                         <subject>History</subject>
>                 </subjects>
>         </item>
>         <item>
>                 <name>bar</name>
>                 <subjects>
>                         <subject>Science</subject>
>                         <subject>History</subject>
>                         <subject>Art</subject>
>                 </subjects>
>         </item>
> </items>
>
> Where each item, as you can see, is categorised.
>
> I'm transforming them, using parameters for inclusion and exclusion,
> roughly like this:
>
> <xsl:stylesheet version="1.0"
> xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
>         <xsl:param name="included" select="'Science'"/>
>         <xsl:param name="excluded" select="'Politics'"/>
>         <xsl:template match="//item">
>                 <xsl:if test="contains(subjects,$included) and
> not(contains(subjects,$excluded))">
>                         <xsl:value-of select="name"/>
>                 </xsl:if>
>         </xsl:template>
> </xsl:stylesheet>
>
> Which selects "bar", because its subjects match the included string and
> don't match the excluded string.
>
> So, all well and good if I only ever have one of each, but now I need to
> add more. What if I might have any number of inclusions and exclusions?
> Say I had a config file like this:
>
> <config>
>         <included>
>                 <subject>Science</subject>
>                 <subject>History</subject>
>         </included>
>         <excluded>
>                 <subject>Politics</subject>
>         </excluded>
> </config>
>
> Allowing an arbitrary number of inclusions and exclusions, how would I
> efficiently test each item?

You can use the set comparison operators = and !=

If that config file you describe above is called "config.xml" then you
can compare each <item> with the values in the config:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>

<xsl:variable name="config" select="document('config.xml')">

<xsl:template match="/">
	<xsl:copy-of select="//item[not($config/config/included/subject !=
current()/subjects/subject)
	][not(subjects/subject = $config/config/excluded/subject)]"/>
</xsl:template>

</xsl:stylesheet>

Running this with your above input gives the output:

<item>
 <name>bar</name>
 <subjects>
   <subject>Science</subject>
   <subject>History</subject>
   <subject>Art</subject>
 </subjects>
</item>

cheers
andrew