XML XPath 1.0 - How to correctly use 'not' function in XPath expression

Question

I'd like to return only the AA nodes that don't contain a BB child node. I'm using XPath 1.0 btw.

Sample xml file:

<?xml version="1.0" encoding="UTF-8"?>
<T>
 <AA>
  <ZZ>z</ZZ>        
 </AA>
 <AA>
  <BB>b1</BB>        
 </AA>
 <AA>
  <BB>b2</BB>        
  <CC>c</CC>        
 </AA>
 <AA>
  <CC>c</CC>        
  <DD>d</DD>        
 </AA>
</T>

So with the above exampe, only the first and last AA nodes should be returned. I've tried something like:

//AA/*[not(BB)]/..

...but this still returns all 4 AA nodes.

Is the 'not' function available in 1.0? If so, what am I doing wrong? thank you...

Sorry, out of habit ... only if I included just one 'my' stmt, huh? — CraigP
– CraigP, Commented Feb 14, 2014 at 13:45

Borodin · Accepted Answer · 2014-02-14 04:13:36Z

2

Your expression selects nodes that are children of AA nodes that do not have BB as children. If you make the assertion about the AA node then you should get what you want:

use strict;
use warnings;

use XML::XPath;

my $xp = XML::XPath->new( filename => 'test.xml');

my $nodeset = $xp->find('//AA[not(BB)]');

foreach my $node ($nodeset->get_nodelist) {
  print "FOUND:\n";
  print ' ', $node->toString, "\n";
}

Which outputs:

FOUND:
 <AA>
  <ZZ>z</ZZ>        
 </AA>
FOUND:
 <AA>
  <CC>c</CC>        
  <DD>d</DD>        
 </AA>

edited Feb 14, 2014 at 4:13

Borodin

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answered Feb 14, 2014 at 2:13

Kyle Burton

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Comments

ikegami · Accepted Answer · 2014-02-14 04:21:57Z

1

Keep in mind that

//AA/*[not(BB)]/..

is just a short way or writing

descendant::AA/child::*[not(child::BB)]/parent::node()

As this makes more obvious, BB doesn't check if the name of the context node is BB, it finds the children named BB.

You're checking if the child elements of AA have child elements BB.

You want to check if the AA elements have child elements BB.

//AA[not(BB)]

edited Feb 14, 2014 at 4:21

answered Feb 14, 2014 at 2:09

ikegami

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1 Comment

CraigP Over a year ago

thank you; yes, that works ... I could of sworn I tried that ... geez!

helderdarocha · Accepted Answer · 2014-02-14 02:09:38Z

0

You can use:

//AA[not(BB)]

The expression you tried selects the elements contained in AA which don't contain BB.

answered Feb 14, 2014 at 2:09

helderdarocha

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