Re: [xml] xpath problem

[Aleksey Sanin <aleksey aleksey com>]

What about

    (//. | //@* | //namespace::*)[ancestor-or-self::node()[ Id='aaa']]

if you want to select <EndUser/> element or

    (//. | //@* | //namespace::*)[ancestor::node()[ Id='aaa']]

if you want <EndUser/> childs only.

Aleksey

Moultrie, Ferrell (ISSAtlanta) wrote:

> Daniel:
>  Yes, XPath is subtle. I'm certainly not an XPath expert. Can you
> suggest any modification to the XPath transform which would make this
> work regardless of the non-significant whitespace/new-line issue? We've
> been working with this for some time now and haven't managed to find a
> solution. TIA for any help or suggestions you are willing to make!
> Ferrell
>
> -----Original Message-----
> From: Daniel Veillard [mailto:veillard redhat com] 
> Sent: Thursday, August 29, 2002 5:16 AM
> To: Aleksey Sanin
> Cc: xml gnome org; Moultrie, Ferrell (ISSAtlanta)
> Subject: Re: [xml] xpath problem
>
>
> On Thu, Aug 29, 2002 at 03:57:09AM -0400, Daniel Veillard wrote:
>  
>
> > On Wed, Aug 28, 2002 at 10:09:01PM -0700, Aleksey Sanin wrote:
> >    
> >
> > > The problem:
> > > ===========================================================
> > > There are two files a.xml and b.xml with a difference of \n in the
> > >      
> last 
>  
>
> > > line:
> > >      
> > yes and at the XPath data model it means the EndUsers node has one
> >    
> more child
>  
>
> > which is a text node with the \n
> >
> >    
> >
> > > --- a.xml ---
> > > <?xml version="1.0"?>
> > > <EndUsers><EndUser Id="aaa"><Version>1.0</Version>
> > > </EndUser>
> > > </EndUsers>
> > > --- b. xml ---
> > > <?xml version="1.0"?>
> > > <EndUsers><EndUser Id="aaa"><Version>1.0</Version>
> > > </EndUser></EndUsers>
> > > -------------
> > > And there is an XPath expression:
> > > (//. | //@* | //namespace::*) [ (ancestor::node() = 
> > > /EndUsers[1]/child::EndUser[ Id='aaa']) ]
> > >
> > > The expected result is that this expression selects all childs of
> > >      
> the 
>  
>
> > > EndUser node with
> > > Id attribute equal to 'aaa' (I know that it's ugly because the Id 
> > > attribute selected w/o node :) ).  
> > > However, it should work! But running this expression on these two
> > >      
> files 
>  
>
> > > gives different results
> > > (correct result in the a.xml case and wrong result in the b.xml
> > >      
> case):
>  
>
> > > [aleksey shell dd]$ ./testXPath --debug -f test.xpath -i a.xml
> > > ========================
> > > Expression: (//. | //@* | //namespace::*)[(ancestor::node() = 
> > > /EndUsers[1]/child::EndUser[ Id='aaa'])]
> > > Object is a Node Set :
> > > Set contains 6 nodes:
> > > 1  ATTRIBUTE Id
> > >    TEXT
> > >      content=aaa
> > > 2  ELEMENT Version
> > > 3  TEXT
> > >    content=1.0
> > > 4  TEXT
> > >    content=
> > > 5  namespace xml href=http://www.w3.org/XML/1998/namespace
> > > 6  namespace xml href=http://www.w3.org/XML/1998/namespace
> > >
> > > [aleksey shell dd]$ ./testXPath --debug -f test.xpath -i b.xml
> > > ========================
> > > Expression: (//. | //@* | //namespace::*)[(ancestor::node() = 
> > > /EndUsers[1]/child::EndUser[ Id='aaa'])]
> > > Object is a Node Set :
> > > Set contains 8 nodes:
> > > 1  ELEMENT EndUser
> > >    ATTRIBUTE Id
> > >      TEXT
> > >        content=aaa
> > > 2  ATTRIBUTE Id
> > >    TEXT
> > >      content=aaa
> > > 3  ELEMENT Version
> > > 4  TEXT
> > >    content=1.0
> > > 5  TEXT
> > >    content=
> > > 6  namespace xml href=http://www.w3.org/XML/1998/namespace
> > > 7  namespace xml href=http://www.w3.org/XML/1998/namespace
> > > 8  namespace xml href=http://www.w3.org/XML/1998/namespace
> > >      
> >  The behaviour of '(//. | //@* | //namespace::*)' seems okay, it
> > selects 11 nodes on a.xml and 10 on b.xml . But the fact that 
> > EndUser get selected in the expression in b.xml is a bug clearly :-(
> >    
>
>  Conclusion: it's not a bug !
>
>  [(ancestor::node() = /EndUsers[1]/child::EndUser[ Id='aaa'])]
> does a comparison between nodesets, defined at
>   http://www.w3.org/TR/xpath#booleans
>
> "If both objects to be compared are node-sets, then the comparison
> will be true if and only if there is a node in the first node-set and
> a node in the second node-set such that the result of performing the
> comparison on the string-values of the two nodes is true."
>
>  in the case of b.xml the string-value of EndUsers and EndUser
> are the same (because there is no \n to differenciate them), so 
> EndUsers matches the criteria and the EndUser child is selected in the
> resutling node-list.
>
>  The bug is in the expression given, it does *not* select all childs
> of the EndUser node !
>
>   NOTABUG, CLOSED
>
>  XPath is subtle :-\
>
> Daniel
>
>