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RE: xsl array alternatives (novice)

2002-09-18 13:12:40
Isaac,

At 03:41 PM 9/18/2002, Stuart wrote:
> Exhibit A. --before
> (many other irrelevent records)...
> <nodeA att1="True" att2="N" att3="1234"/>
> <nodeA att1="True" att2="N" att3="321"/>
> <nodeA att1="True" att2="N" att3="456"/>
> <nodeA att1="True" att2="Y" att3="9876"/>
> <nodeB att1="True" att5="Y" att3="45"/>
> <nodeB att1="True" att5="N" att3="65"/>
> <nodeC att1="True" att7="Y" att3="784"/>
> <nodeC att1="True" att7="Y" att3="412"/>
> <nodeC att1="True" att7="N" att3="635"/>
> ...(many other irrelevent records)
>
> I would like to create xml output that looks something like this:
>
> Exhibit B. --after
> (many irrelevent records)...
> <nodeA att1="True" att2="N" att3="1234"/>
> <nodeA att1="True" att2="N" att3="321"/>
> <nodeA att1="True" att2="N" att3="456"/>
> <nodeB att1="True" att5="N" att3="65"/>
> <nodeC att1="True" att7="N" att3="635"/>
> ...(many irrelevent records that may or may not have duplicate attribute
> names and values)
> <nodeA att1="True" att2="Y" att3="9876"/>
> <nodeB att1="True" att5="Y" att3="45"/>
> <nodeC att1="True" att7="Y" att3="784"/>
> <nodeC att1="True" att7="Y" att3="412"/>
> <end of document/>

Why not use a key:

<xsl:key name="getNodes" match="nodeA|nodeB|nodeC" use="@*"/>

Then all you need to do is:

<xsl:copy-of select="key('getNodes','N')"/>
<xsl:copy-of select="key('getNodes','Y')"/>

This works fine, and in many cases may be the best way to approach it.

A simpler solution is just to filter the elements out with select attributes on apply-templates (or copy-of). This avoids the overhead of the key (as if that were frequently a problem: it's not):

<xsl:template match="parent-of-nodes">
  <xsl:copy-of select="*[(_at_)* = 'N']"/>
  <xsl:copy-of select="*[(_at_)* = 'Y']"/>
</xsl:template>

Like Stuart's solution, this assumes that any attribute marked as 'N' pulls the node into the N category, any attribute marked 'Y' pulls it into the Y category. It depends on the rule for equality of node sets with strings (they are equal if the node set -- here, the set of all an element's attributes -- contains any node equal to the string.) The logic can easily be tightened, of course.

This is a pretty basic application of XSLT; as you can see no procedural thinking (such as where you're going to "put" these nodes, as in an array) is necessary at all.

Cheers,
Wendell


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Wendell Piez                            
mailto:wapiez(_at_)mulberrytech(_dot_)com
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