XSLT Grouping on one subnode through multiple higher level nodes - xslt

Question

I'm fairly new to XSLT but am trying to get an XML file to display a certain node set through XSLT. I am using XSL 1.0. The xml looks like this:
<...>
<entry>
<organizer>
<component>
<observation>
<code displayName="Weight" />
<effectiveTime value="5/21/2013 12:00:00 AM" />
<value value="75" unit="lbs" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="BMI" />
<effectiveTime value="5/21/2013 12:00:00 AM" />
<value value="14.6" unit="98" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="Weight" />
<effectiveTime value="5/20/2013 12:00:00 AM" />
<value value="255" unit="lbs" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="BMI" />
<effectiveTime value="5/20/2013 12:00:00 AM" />
<value value="49.8" unit="98" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="Blood Pressure" />
<effectiveTime value="5/20/2013 12:00:00 AM" />
<value value="100/76" unit="mm Hg" />
</observation>
</component>
</organizer>
</entry>
</...>
What I want the output to look like is something like this:
<table>
<tr>
<td>5/21/2013</td>
<td> </td>
<td>Weight: 75lbs</td>
<td>BMI: 14.6 90</td>
</tr>
<tr>
<td>5/20/2013</td>
<td>Blood Pressure: 100/76 mm Hg</td>
<td>Weight: 255lbs</td>
<td>BMI: 49.8 90</td>
</tr>
</table>
Basically, group by the effectiveTime (within the observation node), and put the blood pressure, the weight and the bmi in subsequent columns. I also need to have a blank table cell if a particular code displayname is not present for that particular date (see blood pressure not listed for the first date).
Thanks for any help. I'm picking up the XSLT, but it's taking time since there is so much.

Answer 1

You don't say which version of XSLT, so I've assumed 2.0:
T:\ftemp>type entries.xml
<entries>
<entry>
<organizer>
<component>
<observation>
<code displayName="Weight" />
<effectiveTime value="5/21/2013 12:00:00 AM" />
<value value="75" unit="lbs" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="BMI" />
<effectiveTime value="5/21/2013 12:00:00 AM" />
<value value="14.6" unit="98" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="Weight" />
<effectiveTime value="5/20/2013 12:00:00 AM" />
<value value="255" unit="lbs" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="BMI" />
<effectiveTime value="5/20/2013 12:00:00 AM" />
<value value="49.8" unit="98" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="Blood Pressure" />
<effectiveTime value="5/20/2013 12:00:00 AM" />
<value value="100/76" unit="mm Hg" />
</observation>
</component>
</organizer>
</entry>
</entries>
T:\ftemp>call xslt2 entries.xml entries.xsl
<table>
<tr>
<td>5/21/2013</td>
<td> </td>
<td>Weight: 75 lbs</td>
<td>BMI: 14.6 98</td>
</tr>
<tr>
<td>5/20/2013</td>
<td>Blood Pressure: 100/76 mm Hg</td>
<td>Weight: 255 lbs</td>
<td>BMI: 49.8 98</td>
</tr>
</table>
T:\ftemp>type entries.xsl
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="2.0">
<xsl:output method="html"/>
<xsl:template match="entries">
<!--dictate the order of the columns this way-->
<xsl:variable name="fields" select="('Blood Pressure','Weight','BMI')"/>
<!--create the table-->
<table>
<!--grouped by time-->
<xsl:for-each-group select="entry"
group-by="organizer/component/observation/effectiveTime/#value">
<tr>
<!--subset of time-->
<td>
<xsl:value-of select="substring-before(
organizer/component/observation/effectiveTime/#value,' ')"/>
</td>
<!--the fields in order-->
<xsl:for-each select="$fields">
<xsl:variable name="this"
select="current-group()[organizer/component/observation/code/#displayName=
current()]/organizer/component/observation/value"/>
<xsl:choose>
<xsl:when test="$this">
<td>
<xsl:value-of
select="concat(.,': ',$this/#value,' ',$this/#unit)"/>
</td>
</xsl:when>
<xsl:otherwise><td> </td></xsl:otherwise>
</xsl:choose>
</xsl:for-each>
</tr>
</xsl:for-each-group>
</table>
</xsl:template>
</xsl:stylesheet>
T:\ftemp>rem Done!

Answer 2

Here is a version of solution using XSLT 1.0 ... rather than using a variable of field names, I coded the column handling for each one.
T:\ftemp>type entries.xml
<entries>
<entry>
<organizer>
<component>
<observation>
<code displayName="Weight" />
<effectiveTime value="5/21/2013 12:00:00 AM" />
<value value="75" unit="lbs" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="BMI" />
<effectiveTime value="5/21/2013 12:00:00 AM" />
<value value="14.6" unit="98" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="Weight" />
<effectiveTime value="5/20/2013 12:00:00 AM" />
<value value="255" unit="lbs" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="BMI" />
<effectiveTime value="5/20/2013 12:00:00 AM" />
<value value="49.8" unit="98" />
</observation>
</component>
</organizer>
</entry>
<entry>
<organizer>
<component>
<observation>
<code displayName="Blood Pressure" />
<effectiveTime value="5/20/2013 12:00:00 AM" />
<value value="100/76" unit="mm Hg" />
</observation>
</component>
</organizer>
</entry>
</entries>
T:\ftemp>call xslt entries.xml entries1.xsl
<table>
<tr>
<td>5/21/2013</td>
<td> </td>
<td>Weight: 75 lbs</td>
<td>BMI: 14.6 98</td>
</tr>
<tr>
<td>5/20/2013</td>
<td>Blood Pressure: 100/76 mm Hg</td>
<td>Weight: 255 lbs</td>
<td>BMI: 49.8 98</td>
</tr>
</table>
T:\ftemp>type entries1.xsl
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="1.0">
<xsl:output method="html"/>
<xsl:key name="times" match="entry"
use="organizer/component/observation/effectiveTime/#value"/>
<xsl:template match="entries">
<!--create the table-->
<table>
<!--grouped by time-->
<xsl:for-each select="entry[generate-id(.)=
generate-id(key('times',
organizer/component/observation/effectiveTime/#value)[1])]">
<tr>
<!--subset of time-->
<td>
<xsl:value-of select="substring-before(
organizer/component/observation/effectiveTime/#value,' ')"/>
</td>
<!--the fields in order-->
<xsl:variable name="values"
select="key('times',
organizer/component/observation/effectiveTime/#value)/
organizer/component/observation"/>
<xsl:choose>
<xsl:when test="$values/code[#displayName='Blood Pressure']">
<td>
<xsl:for-each
select="$values[code/#displayName='Blood Pressure']">
<xsl:value-of
select="concat('Blood Pressure: ',value/#value,' ',value/#unit)"/>
</xsl:for-each>
</td>
</xsl:when>
<xsl:otherwise><td> </td></xsl:otherwise>
</xsl:choose>
<xsl:choose>
<xsl:when test="$values/code[#displayName='Weight']">
<td>
<xsl:for-each
select="$values[code/#displayName='Weight']">
<xsl:value-of
select="concat('Weight: ',value/#value,' ',value/#unit)"/>
</xsl:for-each>
</td>
</xsl:when>
<xsl:otherwise><td> </td></xsl:otherwise>
</xsl:choose>
<xsl:choose>
<xsl:when test="$values/code[#displayName='BMI']">
<td>
<xsl:for-each
select="$values[code/#displayName='BMI']">
<xsl:value-of
select="concat('BMI: ',value/#value,' ',value/#unit)"/>
</xsl:for-each>
</td>
</xsl:when>
<xsl:otherwise><td> </td></xsl:otherwise>
</xsl:choose>
</tr>
</xsl:for-each>
</table>
</xsl:template>
</xsl:stylesheet>
T:\ftemp>rem Done!

Answer 3

<xsl:stylesheet
version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>
<xsl:output method="html" indent="yes" />
<xsl:key name="kObservationByTime" match="observation" use="effectiveTime/#value" />
<xsl:template match="/">
<table>
<tr>
<th>Time</th>
<th>Blood Pressure</th>
<th>Weight</th>
<th>BMI</th>
</tr>
<xsl:apply-templates mode="group" select="
*//observation[
generate-id()
=
generate-id(key('kObservationByTime', effectiveTime/#value)[1])
][position() > last() - 3]
" />
<xsl:sort select="effectiveTime/#value" order="descending" />
</xsl:apply-templates>
</table>
</xsl:template>
<xsl:template match="observation" mode="group">
<xsl:variable name="time" select="effectiveTime/#value" />
<xsl:variable name="thisGroup" select="key('kObservationByTime', $time)" />
<tr>
<td><xsl:value-of select="substring-before($time, ' ')" /></td>
<td><xsl:apply-templates select="$thisGroup[code[#displayName = 'Blood Pressure']]" /></td>
<td><xsl:apply-templates select="$thisGroup[code[#displayName = 'Weight']]" /></td>
<td><xsl:apply-templates select="$thisGroup[code[#displayName = 'BMI']]" /></td>
</tr>
</xsl:template>
<xsl:template match="observation">
<xsl:value-of select="normalize-space(concat(value/#value, ' ', value/#unit))" />
</xsl:template>
</xsl:stylesheet>
gives you
<table>
<tr>
<th>Time</th>
<th>Blood Pressure</th>
<th>Weight</th>
<th>BMI</th>
</tr>
<tr>
<td>5/21/2013</td>
<td></td>
<td>75 lbs</td>
<td>14.6 98</td>
</tr>
<tr>
<td>5/20/2013</td>
<td>100/76 mm Hg</td>
<td>255 lbs</td>
<td>49.8 98</td>
</tr>
</table>
http://www.xmlplayground.com/O9Z9DT
This solution uses an <xsl:key> for grouping.
The [position() > last() - 3] predicate selects the last 2 groups for display. The alternative, [position() < 3], would select the first two. Both work in document order, while <xsl:sort> only affects output order.
Note that due to an unwise choice in date formatting, ordering your results sensibly isn't possible with pretty code.
The non-pretty code to sort your entries by date would look like this:
<xsl:sort select="
concat(
substring-after(substring-after(substring-before(effectiveTime/#value, ' '), '/'), '/'),
'-',
10 + substring-before(effectiveTime/#value, '/'),
'-',
10 + substring-before(substring-after(effectiveTime/#value, '/'), '/')
)
" order="descending" />
... or you simply use a sensible date format and the pain goes away. ;)