ApplyXPath example: statement doesn't do what I think it ought to

[Rob van Wees <r....@chello.nl>]

Hello there,

I'm unfamiliar with the mailing list, please tell me if I should ask
somewhere else.

I have been trying out the ApplyXPAth example with the xalan-j v2_0_0 stuff
and I ran into something I did not quite understand. Could you help me?

When I executed the following XPath statement:

	//name[..//@level=\"2\"|..//class=\"Cleric\"]

on the attached file, I expected to get some output starting with:

	<name>Aid</name>

However, the output was like below:

Loading classes, parsing tmpspells.xml, and setting up serializer
Querying DOM using //name[..//@level="2"|..//class="Cleric"]
<output>
</output>

My question(s):
1) Am I mistaken in the XPAth syntax?
I expected it to behave somewhat like "SELECT name WHERE @level=2 AND
class=Cleric". Is this correct? The previous Xalan version behaved
differently in that it returned "unknown axis 'name'", this version tells me
"No records selected..."

2) Did I do something wrong?
Does XPath support the above construct (multiple clauses in a condition
statement)? It does seem to work for the non-conditional:
	//name|//short-description

3) If it was me (and too if it wasn't), do you know of a proper XPath
(preferably short-notation) explanation? The notation texts at W3C are a
little hard for me to read...

Thanks in advance,

Rob van Wees

Re: ApplyXPath example: statement doesn't do what I think it ought to

[Gary L Peskin <ga...@firstech.com>]

Rob van Wees wrote:
> 
> Hello there,
> 
> I'm unfamiliar with the mailing list, please tell me if I should ask
> somewhere else.

No, here is fine though you'll probably get faster results for straight
XSLT questions on the XSL-LIST (see
http://www.mulberrytech.com/xsl/xsl-list/index.html).

> I have been trying out the ApplyXPAth example with the xalan-j v2_0_0 stuff
> and I ran into something I did not quite understand. Could you help me?
> 
> When I executed the following XPath statement:
> 
>         //name[..//@level=\"2\"|..//class=\"Cleric\"]
> 
> My question(s):
> 1) Am I mistaken in the XPAth syntax?
> I expected it to behave somewhat like "SELECT name WHERE @level=2 AND
> class=Cleric". Is this correct? The previous Xalan version behaved
> differently in that it returned "unknown axis 'name'", this version tells me
> "No records selected..."
> 
> 2) Did I do something wrong?
> Does XPath support the above construct (multiple clauses in a condition
> statement)? It does seem to work for the non-conditional:
>         //name|//short-description

You are using the | operator inside a predicate (the part enclosed by
[]).  I believe that this is parsed as
  //name[..//@level=('2'|..//class='Cleric')]
which is not what you want.  Note that I've converted your \" to ' which
I think makes things more readable.

I think you want
  //name[..//@level='2'] | //name[..//class='Cleric']

which seems to produce what you want.
> 
> 3) If it was me (and too if it wasn't), do you know of a proper XPath
> (preferably short-notation) explanation? The notation texts at W3C are a
> little hard for me to read...

I highly recommend Mike Kay's XSLT Programmer's Reference published by
Wrox, ISBN 1861003129.  A new version is due out in March if you want to
wait.

HTH,
Gary