RE: [xsl] Ways to simplify XSL, complex "select/filter criteria"

["Michael Kay" <mike@xxxxxxxxxxxx>]

I don't think I fully understand the requirement, but it's certainly a case
where your code can be simplified by use of functions. For example you can
define this function

<xsl:function name="f:applies-now" as="xs:boolean">
  <xsl:param name="v" as="element(ns:validFor)"/>
  <xsl:variable name="start" as="xs:dateTime?"
    select="xs:dateTime($v/ns:startDateTime)"/>
  <xsl:variable name="end" as="xs:dateTime?"
    select="xs:dateTime($v/ns:endDateTime)"/>
  <xsl:sequence select="(empty($start) or $start le current-dateTime()) and
                         (empty($end) or $end ge current-dateTime()))"/>
</xsl:function>

and this one

<xsl:function name="f:type" as="xs:QName">
  <xsl:param name="e" as="element()"/>
  <xsl:sequence select="QName($e/@xsi:type, $e)"/>
</xsl:function>

and then you can do things like

<xsl:value-of select="/cdm:Individual/cdm:PartyPlays
                           [f:type(.) eq xs:QName("fn:Employee")]
                           [exists(ns:validFor[f:applies-now(.)])]"/>

Regards,

Michael Kay
http://www.saxonica.com/
http://twitter.com/michaelhkay 

> -----Original Message-----
> From: Stefan Fritz [mailto:sfritz.nospam@xxxxxx] 
> Sent: 18 December 2009 10:07
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: [xsl] Ways to simplify XSL, complex "select/filter criteria"
> 
> Hi all,
> 
> first my environment: Saxon 8.9, XSL and Xpath 2.0, Java
> 
> I have to transform a XML document which contains elements 
> with the same name but different xs:type.
> In addition the elements contain an optional validFor element 
> which defines a time period for the validity of the data.
> 
> The rules to implement is:
> - select element by xsi type
> - select the valid (in time period) element
> - if no time period specified and multiple elements of the 
> same type exist, take the first one
> 
> I have to apply these rules in almost every value-of 
> selection in my XSLT and therefore the XSLT became really a nightmare.
> I hope there is a solution to simplify this. I though about 
> xsl:function, dynamic Xpath (saxon:evaluate,..) but couldn't 
> get it to work.
> Any help more than appreciated!
> 
> Thanks
> Stefan
> 
> simplified XML and XSL:
> 
> <ns:Individual
> xsi:type="ns:Individual"
> xmlns:ns="http://myns";
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";>
> 
> <ns:validFor xsi:type="ns:TimePeriod">
> <ns:startDateTime>1800-01-01T00:00:00</ns:startDateTime>
> <ns:endDateTime/>
> </ns:validFor>
> 
> <ns:PartyPlays xsi:type="ns:Employee">
> <ns:validFor xsi:type="ns:TimePeriod">
> <ns:startDateTime>2005-09-19T00:00:00</ns:startDateTime>
> <ns:endDateTime/>
> </ns:validFor>
> <ns:PartyRoleContactableVia xsi:type="ns:PostalContact">
>                  ...
> </ns:PartyRoleContactableVia>
> <ns:PartyRoleContactableVia xsi:type="ns:PostalContact">
>              ...
> </ns:PartyRoleContactableVia>
> <ns:PartyRoleContactableVia xsi:type="ns:EMailContact"> 
> <ns:validFor xsi:type="ns:TimePeriod"> 
> <ns:endDateTime>2010-09-19T00:00:00</ns:endDateTime>
> </ns:validFor>
> <ns:eMailAddress>email1@xxxxxx</ns:eMailAddress>
> </ns:PartyRoleContactableVia>
> <ns:PartyRoleContactableVia xsi:type="ns:EMailContact"> 
> <ns:validFor xsi:type="ns:TimePeriod"> 
> <ns:endDateTime>2010-09-19T00:00:00</ns:endDateTime>
> </ns:validFor>
> <ns:eMailAddress>email2@xxxxxx</ns:eMailAddress>
> </ns:PartyRoleContactableVia>
> </ns:PartyPlays>
> </ns:Individual>
> 
> 
> <?xml version="1.0" encoding="UTF-8"?>
> <xsl:stylesheet version="2.0" 
> xmlns:xsl="http://www.w3.org/1999/XSL/Transform"; 
> xmlns:cdm="http://myns"; 
> xmlns:xs="http://www.w3.org/2001/XMLSchema"; 
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";>
> <xsl:output method="text"/>
> 
> <xsl:template match="/">
> <xsl:value-of
> select="/cdm:Individual/cdm:PartyPlays[contains(@xsi:type,'Emp
> loyee')][
> if(string-length(cdm:validFor/cdm:startDateTime) gt 0 and
> string-length(cdm:validFor/cdm:endDateTime) gt 0) then
> (xs:dateTime(cdm:validFor/cdm:startDateTime) lt 
> current-dateTime() and 
> xs:dateTime(cdm:validFor/cdm:endDateTime)gt 
> current-dateTime()) else 
> if(string-length(cdm:validFor/cdm:startDateTime) gt 0) then
> (xs:dateTime(cdm:validFor/cdm:startDateTime) lt 
> current-dateTime()) else 
> if(string-length(cdm:validFor/cdm:endDateTime) gt 0) then ( 
> xs:dateTime(cdm:validFor/cdm:endDateTime)gt current-dateTime()) else
> 1
> ]/cdm:PartyRoleContactableVia[contains(@xsi:type,'EMailContact')][
> if(string-length(cdm:validFor/cdm:startDateTime) gt 0 and
> string-length(cdm:validFor/cdm:endDateTime) gt 0) then
> (xs:dateTime(cdm:validFor/cdm:startDateTime) lt 
> current-dateTime() and 
> xs:dateTime(cdm:validFor/cdm:endDateTime)gt 
> current-dateTime()) else 
> if(string-length(cdm:validFor/cdm:startDateTime) gt 0) then
> (xs:dateTime(cdm:validFor/cdm:startDateTime) lt 
> current-dateTime()) else 
> if(string-length(cdm:validFor/cdm:endDateTime) gt 0) then ( 
> xs:dateTime(cdm:validFor/cdm:endDateTime)gt current-dateTime()) else
> 1
> ][1]/cdm:eMailAddress[1]"/>
> </xsl:template>
> </xsl:stylesheet>