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RE: [xsl] Variable Substitution In A Select Statement

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David,

First, a big "Thanks!" for your kind and timely help!  Talk about a quick
response.

Here is my solution:

<xsl:variable name="expression" select="concat($Axpath_new, '/@id')" />
<xsl:apply-templates select ="$FileA/saxon:evaluate($expression)" />

The $FileA variable references an external document and with my new gained
knowledge of 'saxon.evaluate()' I'm able to locate the proper @id along the
Xpath specified in $Axpath.


Cheers,

Raymond Lillibridge





-----Original Message-----
From: David Carlisle [mailto:davidc@xxxxxxxxx]
Sent: Tuesday, May 24, 2011 9:22 AM
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: [xsl] Variable Substitution In A Select Statement

On 24/05/2011 14:07, Raymond Lillibridge wrote:
> xsl-list Members,
>
> Using Saxon-PE 9.3.0.5J from Saxonica (XSLT 2.0):
>
> The following template matches on the specified @id in $FileA.  Just what I
need.
>
> <xsl:apply-templates
> select="$FileA/book/level1[2]/level2[4]/section[2]/@id" />
>
> However, if I have a variable, $Axpath_new, valued at "book/level1[2]/level
2[4]/section[2]", the following template returns nothing:
>
> <xsl:apply-templates select ="$FileA/$Axpath_new/@id" />
>
> Testing a multitude of methods, I could never get a variable to work in the
select statement.
> After much studying about how to make the template work properly, I
> read that I could try using the extension function node-set().
> Further research stated that my free version of Saxon9 doesn't include
> those extensions but the Saxon9pe version does.  So, I purchased a
> copy of Saxon9pe and installed it yesterday.  (Also, I believe I read
> that if I was using XSLT 2.0, I wouldn't need to use the node-set()
> function.)
>
> Any way, it seems like such a simple thing but I'm at a loss, and I'm asking
for your kind assistance.
>

actually having evaluation at run time is quite a big thing 9and not available
in most languages) as it means having all the parsing machinery available
which is not normally in the compiled code.
If you have  a string  x with value " + 2" in C or java or fortran or ...
you can't just go 3 x  and have it expand to 3 + 2 and evaluate to 5.

However for some reason it's quite common to expect that xslt has this
feature.

to use saxon:evaluate you need to declare the saxon extension namespace then
something like
saxon:evaluate(concat('$FileA,'/',$Axpath_new.'/@id'))
ie build up the xpath you want to evaluate as a single string then pass it to
the function.

You didn't say why you are needing evaluation though, are you picking up the
xpaths from an external file? otherwise it may be better to store the sequence
of nodes selected by book/level1[2]/level 2[4]/section[2] in a variable,
rather than the string "book/level1[2]/level 2[4]/section[2]"
then you could just do $variable/'id
to select the id attributes.

David


David

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