XSLT count of items meeting a calculated value - variables

Question

I have a set of XML data that I'm trying to go through and determine how many items have a date of less than 1 week old.
DATA:
<events>
<event>
<eventDate>20110504</date>
<description>whatever</description>
</event>
<event>
<eventDate>20110720</date>
<description>whatever</description>
</event>
.
.
.
<event>
<eventDate>20111210</date>
<description>whatever</description>
</event>
</events>
XSLT:
<xsl:variable name="events" select="sc:item('/sitecore/content/Home/Upcoming Events',.)" />
<xsl:variable name="now" select="dateutil:get_IsoNow()" />
<xsl:variable name="counter" select="0" />
<xsl:template match="*">
<xsl:apply-templates select="$sc_item" mode="main"/>
</xsl:template>
<xsl:template match="*" mode="main">
<xsl:choose>
<xsl:when test="count($events/item) > 0">
<xsl:for-each select="$events/item">
<xsl:sort select="sc:fld('eventDate',.)" order="ascending"/>
<xsl:variable name="date_difference">
<xsl:call-template name="date-difference">
<xsl:with-param name="item-year" select="substring(sc:fld('eventDate',.),1,4)" />
<xsl:with-param name="item-month" select="substring(sc:fld('eventDate',.),5,2)" />
<xsl:with-param name="item-day" select="substring(sc:fld('eventDate',.),7,2)" />
<xsl:with-param name="today-year" select="substring(substring($now,1,8),1,4)" />
<xsl:with-param name="today-month" select="substring(substring($now,1,8),5,2)" />
<xsl:with-param name="today-day" select="substring(substring($now,1,8),7,2)" />
</xsl:call-template>
</xsl:variable>
<xsl:if test="($date_difference < 8)">
<p>
<sc:text field="eventDate" /><br />
<sc:text field="description" />
</p>
**** Increment a counter variable ****
$counter++
</xsl:if>
</xsl:for-each>
**** Check the counter variable ****
<xsl:if test="($counter = 0)">
<p>No upcoming events are scheduled at this time.</p>
</xsl:if>
</xsl:when>
<xsl:otherwise>
<p>No upcoming events are scheduled at this time.</p>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
<xsl:template name="date-difference">
<xsl:param name="item-year" />
<xsl:param name="item-month" />
<xsl:param name="item-day" />
<xsl:param name="today-year" />
<xsl:param name="today-month" />
<xsl:param name="today-day" />
<xsl:variable name="jul-item">
<xsl:call-template name="calculate-julian-day">
<xsl:with-param name="year" select="$item-year" />
<xsl:with-param name="month" select="$item-month" />
<xsl:with-param name="day" select="$item-day" />
</xsl:call-template>
</xsl:variable>
<xsl:variable name="jul-today">
<xsl:call-template name="calculate-julian-day">
<xsl:with-param name="year" select="$today-year" />
<xsl:with-param name="month" select="$today-month" />
<xsl:with-param name="day" select="$today-day" />
</xsl:call-template>
</xsl:variable>
<xsl:value-of select="$jul-today - $jul-item" />
</xsl:template>
<xsl:template name="calculate-julian-day">
<xsl:param name="year" />
<xsl:param name="month" />
<xsl:param name="day" />
<xsl:variable name="a" select="floor((14 - $month) div 12)" />
<xsl:variable name="y" select="$year + 4800 - $a" />
<xsl:variable name="m" select="$month + 12 * $a - 3" />
<xsl:value-of select="$day + floor((153 * $m + 2) div 5) + $y * 365 + floor($y div 4) - floor($y div 100) + floor($y div 400) - 32045" />
</xsl:template>
I know that I can't change the value of a variable in XSLT since they are actually constants.
I know that I need to use recursion of some sort.
I just can't figure out how to do this... I am truly stumped.
Could someone please help?

Answer 1

Couldn't you determine the string value of a "one week ago" date, then do a textual comparison using XPath?
count(string(event/eventDate) > $oneweekagodatestring)

Answer 2

Replace in your code this:
L o n g C o d e
**** Increment a counter variable ****
$counter++
with:
<xsl:variable name="vHits">
L o n g C o d e
<!-- If the condition is true -->
<xsl:text>1</xsl:text>
</xsl:variable>
and this code:
**** Check the counter variable ****
<xsl:if test="($counter = 0)">
<p>No upcoming events are scheduled at this time.</p>
</xsl:if>
with:
<xsl:if test="(string-length($vHits = 0)">
<p>No upcoming events are scheduled at this time.</p>
</xsl:if>
Complete code example:
This transformation demonstrates "counter-less" computing with XSLT :)
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text"/>
<xsl:strip-space elements="*"/>
<xsl:template match="/*">
<xsl:variable name="vHits">
<xsl:apply-templates/>
</xsl:variable>
<xsl:value-of select="string-length($vHits)"/>
<xsl:text> numbers fulfil x^2 <= 10</xsl:text>
</xsl:template>
<xsl:template match="num">
<xsl:if test="not(. * . > 10)">1</xsl:if>
</xsl:template>
</xsl:stylesheet>
When applied on this XML document:
<nums>
<num>01</num>
<num>02</num>
<num>03</num>
<num>04</num>
<num>05</num>
<num>06</num>
<num>07</num>
<num>08</num>
<num>09</num>
<num>10</num>
</nums>
the wanted, correct result is produced:
3 numbers fulfil x^2 <= 10

Answer 3

If you are using Sitecore you can always use some of the built-in date functions to get year,month and day out without resorting to processing substrings etc.
<xsl:variable name="selectedDate">20111212</xsl:variable>
<xsl:variable name="isoSelectedDate" select="date:ToIsoDate(date:ParseDateTime($selectedDate,date:IsoDateToDateTime(sc:isoNow())))"/>
<xsl:variable name="day" select="sc:day($isoSelectedDate)"/>
<xsl:variable name="month" select="sc:month($isoSelectedDate)"/>
<xsl:variable name="year" select="sc:year($isoSelectedDate)"/>
I think Dimitre's answer works well but this may increase the readability slightly :)

Answer 4

I ended up using the "one week ago" date suggestion. It took quite a bit of work to come up with the template to create the variable for "$oneweekagodatestring". However, I got it working:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:sc="http://www.sitecore.net/sc"
xmlns:dot="http://www.sitecore.net/dot"
xmlns:dateutil="http://www.sitecore.net/dateutil"
exclude-result-prefixes="dot sc dateutil">
<!-- output directives -->
<xsl:output method="html" indent="no" encoding="UTF-8" />
<!-- parameters -->
<xsl:param name="lang" select="''"/>
<xsl:param name="id" select="''"/>
<xsl:param name="sc_item"/>
<xsl:param name="sc_currentitem"/>
<!-- variables -->
<xsl:variable name="events" select="sc:item('/sitecore/content/Home/About/News Center/Upcoming Events',.)" />
<xsl:variable name="now" select="dateutil:get_IsoNow()" />
<!-- entry point -->
<xsl:template match="*">
<xsl:apply-templates select="$sc_item" mode="main"/>
</xsl:template>
<!--==============================================================-->
<!-- main -->
<!--==============================================================-->
<xsl:template match="*" mode="main">
<xsl:variable name="current_date">
<xsl:call-template name="adjust-date">
<xsl:with-param name="date" select="substring-before($now,'T')"/>
<xsl:with-param name="days" select="-7"/>
</xsl:call-template>
</xsl:variable>
<xsl:choose>
<xsl:when test="count($events/item[sc:fld('Event Title',.)!='' and substring-before(sc:fld('Event Date',.),'T') > $current_date]) > 0">
<xsl:for-each select="$events/item[sc:fld('Event Title',.)!='' and substring-before(sc:fld('Event Date',.),'T') > $current_date]">
<xsl:sort select="sc:fld('Event Date',.)" order="ascending"/>
<p>Output for event information goes here.</p>
</xsl:for-each>
</xsl:when>
<xsl:otherwise>
<p>No upcoming events are scheduled at this time.</p>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
<!--======================================================================-->
<!-- Add or subtract days to or from a date -->
<!-- -->
<!-- This template is from Boris Gomiunik. I found it here: -->
<!-- http://www.sharepointboris.net/2008/11/xsl-template-for-adding-days/ -->
<!--======================================================================-->
<xsl:template name="adjust-date">
<xsl:param name="date"/>
<xsl:param name="days"/>
<xsl:param name="oldMonth"><xsl:value-of select="substring($date,5,2)"/></xsl:param>
<xsl:param name="oldYear"><xsl:value-of select="substring($date,1,4)"/></xsl:param>
<xsl:param name="oldDay"><xsl:value-of select="substring($date,7,2)"/></xsl:param>
<xsl:param name="newMonth">
<xsl:choose>
<xsl:when test="$oldMonth = '01'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 31">01</xsl:when>
<xsl:otherwise>02</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '02'">
<xsl:choose>
<xsl:when test="($oldYear mod 4 = 0 and number($oldDay) + $days <= 29) or ($oldYear mod 4 != 0 and number($oldDay) + $days <= 28)">02</xsl:when>
<xsl:otherwise>03</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '03'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 31">03</xsl:when>
<xsl:otherwise>04</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '04'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 30">04</xsl:when>
<xsl:otherwise>05</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '05'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 31">05</xsl:when>
<xsl:otherwise>06</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '06'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 30">06</xsl:when>
<xsl:otherwise>07</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '07'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 31">07</xsl:when>
<xsl:otherwise>08</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '08'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 31">08</xsl:when>
<xsl:otherwise>09</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '09'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 30">09</xsl:when>
<xsl:otherwise>10</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '10'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 31">10</xsl:when>
<xsl:otherwise>11</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '11'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 30">11</xsl:when>
<xsl:otherwise>12</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '12'">
<xsl:choose>
<xsl:when test="number($oldDay) + $days <= 31">12</xsl:when>
<xsl:otherwise>01</xsl:otherwise>
</xsl:choose>
</xsl:when>
</xsl:choose>
</xsl:param>
<xsl:param name="newYear">
<xsl:choose>
<xsl:when test="$oldMonth = '12' and (number($oldDay) + $days) >= 31"><xsl:value-of select="number($oldYear) + 1"/></xsl:when>
<xsl:otherwise><xsl:value-of select="$oldYear"/></xsl:otherwise>
</xsl:choose>
</xsl:param>
<xsl:param name="newDay">
<xsl:choose>
<xsl:when test="$oldMonth = '01'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 31"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '02'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise>
<xsl:choose>
<xsl:when test="$oldYear mod 4 = 0">
<xsl:value-of select="number($oldDay) + $days - 29"/>
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="number($oldDay) + $days - 28"/>
</xsl:otherwise>
</xsl:choose>
</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '03'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 31"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '04'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 30"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '05'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 31"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '06'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 30"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '07'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 31"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '08'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 31"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '09'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 30"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '10'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 31"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '11'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 30"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:when test="$oldMonth = '12'">
<xsl:choose>
<xsl:when test="$newMonth = $oldMonth"><xsl:value-of select="number($oldDay) + $days"/></xsl:when>
<xsl:otherwise><xsl:value-of select="number($oldDay) + $days - 31"/></xsl:otherwise>
</xsl:choose>
</xsl:when>
</xsl:choose>
</xsl:param>
<xsl:value-of select="$newYear"/>
<xsl:value-of select="$newMonth" />
<xsl:if test="$newDay < 10">0</xsl:if><xsl:value-of select="$newDay"/>
</xsl:template>
</xsl:stylesheet>