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FW: [xsl] Passing sort criteria as a paramter

From: David B. Bitton <david@codenoevil.com>
Date: Fri, 25 Jan 2002 10:30:20 -0500 (EST)
To: xsl-editors@w3.org
Message-id: <CC8ECFB81EE5D511AE7500065B199AB30FF5C0@smtp.nyc.banklink.com>
As requested by Jeni Tennison, I am forwarding you my post from the
xsl-list.  I am in need of an evaluate function so I can pass an element
name and predicate into a stylesheet as a param.

Basically, I pass the element that I used to sort by as a param, so my
xsl:sort's select attribute looks like this:

select="*[local-name() = $sortby]"

But I have an instance where I need this:

select="Amount[../IsCredit=1]"

Now I understand that I could do

Select="*[local-name() = $sortby][../IsCredit=1]"

But that is not applicable for any other element other than Amount (and
only a credit amount).  This is all because we display debits and
credits in different columns, and we allow the user to sort be either
column. Unfortunately the only way I have to differentiate a credit from
a debit is a sibling flag, IsCredit, which can be either 1 or 0, which
as you can see, would be used as a predicate against the Amount element.

Hopefully this will be considered for the next version of XPath.
Thanks.

-----Original Message-----
From: Jeni Tennison [mailto:jeni@jenitennison.com] 
Sent: Friday, January 25, 2002 5:25 AM
To: David B. Bitton
Cc: xsl-list@lists.mulberrytech.com
Subject: Re: [xsl] Passing sort criteria as a paramter


Hi David,

> You seemed to get this msg to the list. Wendell, thanks. I didn't 
> think of that. BTW, can I use an xsl:attribute tag for another xsl 
> element?

Since Wendell nabbed the other question, I'll answer this one ;)

I take it you're asking whether you can use xsl:attribute to dynamically
create an attribute on an XSLT element. So you're asking if you can do:

  <xsl:sort>
    <xsl:attribute name="select">
      <xsl:value-of select="$sortby" />
    </xsl:attribute>
  </xsl:sort>

As a way of getting around the fact that $sortby is a string and you
want to interpret it as an XPath expression.

The answer is no, you can't. You can only use xsl:attribute to add
attributes onto result elements (whether created with literal result
elements or with xsl:element).

Of course if the 'xsl:sort' were a literal result element, then it would
be fine. So if you were generating a stylesheet from your stylesheet,
and set up a namespace alias for the XSLT namespace so that 'oxsl' was
the prefix used for the XSLT elements you're generating, you can do:

  <oxsl:sort>
    <xsl:attribute name="select">
      <xsl:value-of select="$sortby" />
    </xsl:attribute>
  </oxsl:sort>

and it will generate:

  <oxsl:sort select="Amount[../IsCredit = 1]" />

By the way, I suggest that you forward your use case on to
xsl-editors@w3.org - hopefully if they receive enough use cases then
they will add an evaluate() function to XSLT 2.0, so that you could just
do:

  <xsl:sort select="evaluate($sortby)" />

Cheers,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/
Received on Friday, 25 January 2002 12:23:23 GMT

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