Thanks to yourself, Andrew and Wolfgang for your suggestions, which I received
after I sent my own solution (stupid work Exchange server :). I knew about
max() but had a temporary brain freeze as I was trying to do three things at
once on a deadline this morning!
I did add the [1] as well to filter out identical duplicates. I would have
considered adding this to the bundle of keys I'm using elsewhere in the
transform, but since performance wasn't significantly affected, I didn't
bother. But I'll definitely do that if the files get any larger - I'm a big fan
of keys. :)
So thanks to everyone and sorry I didn't see your responses sooner!
-----Original Message-----
From: Tony Graham [mailto:tgraham(_at_)mentea(_dot_)net]
Sent: 05 September 2011 11:19
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: Re: [xsl] Filter by id and date
On Mon, September 5, 2011 10:36 am, Emma Burrows wrote:
...
<items>
<item id='1' date='2011'>Item1</item>
<item id='2' date='2009'>Item2</item>
<item id='3' date='2002'>Item3</item>
<item id='2' date='2011'>Item2</item>
<item id='3' date='2002'>Item3</item>
</items>
For example, the Xpath in question looks like this right now (long-winded
but more efficient path-finding syntax simplified to // for this example,
and $idref obviously contains a valid id):
<xsl:value-of select="normalize-space(//item[@id=$idref])"/>
What is the best way to filter that to return only the item whose @date is
the highest for all items with @id=$idref?
The one-line solution is:
normalize-space(//item[@id=$item][@date = max(../item[@id=$item]/@date)][1])
Note the '[1]' to get rid of duplicates such as 'Item3' in your example.
You've already received a solution from Andrew Welch that first makes a
variable for all the possible matching values. That would generally be
clearer and easier to understand when you come back to it in six months
time.
If you have a lot of data with a lot of duplicates in any order, it may be
simplest to process the data once to sort it by date and then change your
@select to "normalize-space(//item[@id=$idref][1])".
BTW, have you looked at using xsl:key? Would it be possible to replace
the long and complicated XPath with a xsl:key that indexes the <item> with
a key based on, say, the string-join() of the significant variable data
from the XPath so you can just lookup the <item>s?)
Regards,
Tony Graham tgraham(_at_)mentea(_dot_)net
Consultant http://www.mentea.net
Mentea 13 Kelly's Bay Beach, Skerries, Co. Dublin, Ireland
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
XML, XSL FO and XSLT consulting, training and programming
--~------------------------------------------------------------------
XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
To unsubscribe, go to: http://lists.mulberrytech.com/xsl-list/
or e-mail: <mailto:xsl-list-unsubscribe(_at_)lists(_dot_)mulberrytech(_dot_)com>
--~--
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please visit http://www.messagelabs.com/email
______________________________________________________________________
--~------------------------------------------------------------------
XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
To unsubscribe, go to: http://lists.mulberrytech.com/xsl-list/
or e-mail: <mailto:xsl-list-unsubscribe(_at_)lists(_dot_)mulberrytech(_dot_)com>
--~--