Re: [xsl] explicit filter

[Jeni Tennison <mail@xxxxxxxxxxxxxxxx>]

Hi Torsten,

> Unfortunately I need to filter the node set on something much more
> comlex. So I thouhght I could traverse the nodes, test them and
> return the good ones. Unfortunately this doesn't seem to work... So
> I tried a simple node set copy first. But this didn't work either:

When you copy nodes, you're creating nodes in the result tree or (if
you do it in a variable) in a result tree fragment.  If you do:

>     <xsl:variable name="filtered_elements">
>       <xsl:for-each select="$elements">
>         <xsl:copy><xsl:copy-of select="@*"/></xsl:copy>
>       </xsl:for-each>
>     </xsl:variable>

you get a result tree fragment that has shallow-ish copies of the
filtered elements (i.e. they have attributes but don't have content).

[Actually I think you probably want deep copies, use xsl:copy-of
instead:

  <xsl:variable name="filtered_elements_rtf">
     <xsl:for-each select="$elements">
        <xsl:copy-of select="." />
     </xsl:for-each>
  </xsl:variable>]

To access those nodes as a node set, you have to turn the result tree
fragment into a node set, using exsl:node-set() if your processor
supports it or its proprietary node-set() function if it doesn't.

   <xsl:variable name="filtered_elements"
                 select="exsl:node-set($filtered_elements_rtf)/*" />

This compromises the portability of your stylesheet somewhat; you
might want to filter the elements lower down in the stylesheet, where
you're actually thinking about doing something with them instead, but
it's hard to tell from your description.

[General point, and another plug - XPaths can be pretty complex, but
they do sometimes fall down, particularly when there are conditional
strings or numbers involved.  If your processor supports func:function
(see http://www.exslt.org/func/elements/function) then you could
create a boolean function to test the nodes and filter them.]

I hope that helps,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/



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