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Ron Bernard

Subject: Help With Updating Attributes Using XSLT
Author: Ron Bernard
Date: 14 Aug 2009 11:05 AM

Hello. I am really new to xslt. I have an xml file that is created dynamically and contains attributes that need to be updated. I was told that using an xsl stylesheet to update the attributes would be a lot faster. The portion of my xml that I would like to update is as follows:
<mychart>
<data>
<attributes>
<attribute name="title">Station Capacity: LAS</attribute>
</attributes>
<series id="Taxi In" name="Taxi In" type="Bar" color="Red">
<tooltip enabled="true">
<format>Series name: {%SeriesName}
Point value: {%Value}{numDecimals:0}
</format>
</tooltip>
<point id="03:00" name="07/22/2009 03:00" y="0" x="03:00"/>
<point id="03:15" name="07/22/2009 03:15" y="0" x="03:15"/>
<point id="03:30" name="07/22/2009 03:30" y="0" x="03:30"/>
</series>
<series id="At Gate" name="At Gate" type="Bar" color="Blue">
<tooltip enabled="true">
<format>Series name: {%SeriesName}
Point value: {%Value}{numDecimals:0}
</format>
</tooltip>
<point id="03:00" name="07/22/2009 03:00" y="0" x="03:00"/>
<point id="03:15" name="07/22/2009 03:15" y="0" x="03:15"/>
<point id="03:30" name="07/22/2009 03:30" y="0" x="03:30"/>
</series>
<series id="Taxi Out" name="Taxi Out" type="Bar" color="Gold">
<tooltip enabled="true">
<format>Series name: {%SeriesName}
Point value: {%Value}{numDecimals:0}</format>
</tooltip>
<point id="03:00" name="07/22/2009 03:00" y="0" x="03:00"/>
<point id="03:15" name="07/22/2009 03:15" y="0" x="03:15"/>
<point id="03:30" name="07/22/2009 03:30" y="0" x="03:30"/>
</series>
<series id="Scheduled" name="Scheduled" type="Marker">
<tooltip enabled="true">
<format>Series name: {%SeriesName}
Point value: {%Value}{numDecimals:0}
</format>
</tooltip>
<point id="03:00" name="07/22/2009 03:00" y="17" x="03:00"/>
<point id="03:15" name="07/22/2009 03:15" y="17" x="03:15"/>
<point id="03:30" name="07/22/2009 03:30" y="17" x="03:30"/>
</series>
</data>
</mychart>

Based on an update that I receive from my server, I would need to update the y attribute of the point node based on the point id and the series id which is the parent node of point. Can anyone help me with this?

Thanks

Tony Lavinio

Subject: Help With Updating Attributes Using XSLT
Author: Tony Lavinio
Date: 14 Aug 2009 04:11 PM

Which version of XSLT, and which version of Stylus Studio are you using?

Ron Bernard

Subject: Help With Updating Attributes Using XSLT
Author: Ron Bernard
Date: 14 Aug 2009 04:38 PM

We are evaluationg stylus studio 2009 and using xsl 1.0

Tony Lavinio

Subject: Help With Updating Attributes Using XSLT
Author: Tony Lavinio
Date: 17 Aug 2009 09:35 AM

Well, I think you should do more than evaluate it, I think you should buy it :)

But in response to your query, the way to handle this is with what's called an "identity transform." You want to copy everything that is unchanged, and intercept and change only what you need to. This example passes in the change detail through three parameters: series_id, point_id, and then the new_y value.

<?xml version="1.0" encoding="US-ASCII"?>

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:param name="series_id"/>
<xsl:param name="point_id"/>
<xsl:param name="new_y"/>
<xsl:output method="xml" encoding="US-ASCII"/>
<xsl:template match="node()|@*">
<xsl:copy>
<xsl:apply-templates select="@*|node()"/>
</xsl:copy>
</xsl:template>

<xsl:template match="point">
<point id="{@id}" name="{@name}" x="{@x}">
<xsl:attribute name="y">
<xsl:choose>
<xsl:when test="../@id = $series_id and @id = $point_id">
<xsl:value-of select="$new_y"/>
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="@y"/>
</xsl:otherwise>
</xsl:choose>
</xsl:attribute>
</point>
</xsl:template>
</xsl:stylesheet>

Ron Bernard

Subject: Help With Updating Attributes Using XSLT
Author: Ron Bernard
Date: 17 Aug 2009 07:55 PM

I tried this out and it works. Thanks so much for your help. A question I wanted to ask is our original method of updating attributes involed using XPath and javascript. Here is an example of how we accomplished this:

updtXmlDoc.selectSingleNode("//series[@id='Taxi In']/point[@id='03:00']").setAttribute("y",'22');

My question is, is it faster to use the xsl stylesheet, or use xpath, and is there a way to show or compare the two approaches in stylus studio?

Again thanks for your help.

Tony Lavinio

Subject: Help With Updating Attributes Using XSLT
Author: Tony Lavinio
Date: 18 Aug 2009 08:42 AM

If the files are relatively small, there is probably no material
difference between the approaches, so you should use whichever is
simpler for you.

Ron Bernard

Subject: Help With Updating Attributes Using XSLT
Author: Ron Bernard
Date: 20 Aug 2009 02:22 PM

We are roughly looking at about 600+ lines of xml. I guess the only issue I would have with the xslt approach is that I would not know if something changed or not.

Another action needs to be performed based on if the xml attribute has changed. With the xpath approach I can compare the value in the xml and then set some type of flag that lets me know that I need to perform the new action. The problem with this is I need to run the query twice. Once to do the comparison, and again to make the action update.

Is there a way to get a return value from xslt that would let me know if a value has changed and would therefore allow me to set the flag to perform the seperate action?

Thanks so much for your help.

Tony Lavinio

Subject: Help With Updating Attributes Using XSLT
Author: Tony Lavinio
Date: 22 Aug 2009 04:40 PM

Unless you use extension functions, the only "return value" from
XSLT is the transformed output.

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