Ebenezer wrote:
> Let's suppose I have some nodes in an XML file, with an URL attribute:
> 
> <node url="mypage.php?name1=value1&foo=bar&foo2=bar2&name2=value0" />
> <node url="myotherpage.php?name4=value4&foo=bar3&foo2=bar5&name2=value8" />
> 
> and so on.
> 
> Let's suppose I want to retrieve this @url parameter, BUT ONLY with the 
> values, in querystring, associated with "foo" and "foo2" (thus 
> discarding name1, name2, name4 and every other different ones).
> 
> In other words, I must obtain:
> 
> mypage.php?foo=bar&foo2=bar2
> myotherpage.php?&foo=bar3&foo2=bar5
> ... and so on.
> 
> Is there a convenient way, in a transformation with XSL, to obtain this 
> string manipulation? (I'd prefer to stick to XSLT1.0, if possible)

Well
   substring-before(node/@url, '?')
would give you the file name, the query string would need to be parsed 
which needs a recursive template or an extension function in XSLT 1.0. 
In XSLT 2.0 you could use the tokenize function and/or xsl:analyze-string:

<xsl:stylesheet
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"
   xmlns:mf="http://example.com/2008/mf"
   exclude-result-prefixes="xsd mf"
   version="2.0">

   <xsl:function name="mf:get-query" as="xsd:string">
     <xsl:param name="qs" as="xsd:string"/>
     <xsl:param name="params" as="xsd:string*"/>
     <xsl:variable name="filtered-qs" as="xsd:string*">
       <xsl:for-each select="tokenize($qs, '&amp;')">
         <xsl:analyze-string
           select="."
           regex="({string-join($params, '|')})=\w*">
           <xsl:matching-substring>
             <xsl:sequence select="regex-group(0)"/>
           </xsl:matching-substring>
         </xsl:analyze-string>
       </xsl:for-each>
     </xsl:variable>
     <xsl:sequence select="string-join($filtered-qs, '&amp;')"/>
   </xsl:function>

   <xsl:template match="node">
     <xsl:value-of select="concat(substring-before(@url, '?'), '?', 
mf:get-query(substring-after(@url, '?'), ('foo', 'foo2')))"/>
   </xsl:template>

</xsl:stylesheet>


-- 

	Martin Honnen
	http://JavaScript.FAQTs.com/