XPath and namespaces...

[Stefan Franke]

Hi,
I've got a little bit of a problem when dealing with namespaces and XPath.

I'm trying very basic things, like showing all the nodes of one particular
namespace. Here is my XPath statement:
//*[local-name() = 'buch' and namespace-uri() =
'http://www.example.com/buecher']

Unfortunately this doesn't work. I have found several ways to solve this
with XSLT, but I need the pure XPath statement.

My XML file looks like this:

<?xml version="1.0"?>
<!-- Dateiname: Sammlung.xml -->
<SAMMLUNG
xmlns:buch="http://www.example.com/buecher"
xmlns:cd="http://www.example.com/cds">

<buch:ARTIKEL Status="vorhanden">
<buch:TITEL>The Adventures of Huckleberry Finn</buch:TITEL>
<buch:AUTOR>Mark Twain</buch:AUTOR>
<buchREIS>12.75</buchREIS>
</buch:ARTIKEL>
<cd:ARTIKEL>
<cd:TITEL>Violinkonzert D-Dur</cd:TITEL>
<cd:KOMPONIST>Beethoven</cd:KOMPONIST>
<cdREIS>14.95</cdREIS>
</cd:ARTIKEL>
</SAMMLUNG>


Could anyone please give me a hint how to solve this problem?

Thanks,
Stefan

 

[Martin Honnen]

Stefan Franke wrote:

I've got a little bit of a problem when dealing with namespaces and XPath.

I'm trying very basic things, like showing all the nodes of one particular
namespace. Here is my XPath statement:
//*[local-name() = 'buch' and namespace-uri() =
'http://www.example.com/buecher']

Unfortunately this doesn't work.

What do you mean by "doesn't work"? Do you get an error? Which software
are you using to test that XPath expression?

My XML file looks like this:

<?xml version="1.0"?>
<!-- Dateiname: Sammlung.xml -->
<SAMMLUNG
xmlns:buch="http://www.example.com/buecher"
xmlns:cd="http://www.example.com/cds">

<buch:ARTIKEL Status="vorhanden">
<buch:TITEL>The Adventures of Huckleberry Finn</buch:TITEL>
<buch:AUTOR>Mark Twain</buch:AUTOR>
<buchREIS>12.75</buchREIS>
</buch:ARTIKEL>
<cd:ARTIKEL>
<cd:TITEL>Violinkonzert D-Dur</cd:TITEL>
<cd:KOMPONIST>Beethoven</cd:KOMPONIST>
<cdREIS>14.95</cdREIS>
</cd:ARTIKEL>
</SAMMLUNG>

Well looking at your example XML the expression

//*[local-name() = 'buch' and namespace-uri() =
'http://www.example.com/buecher']

will not find any element as the XML doesn't contain any
<buch xmlns="http://www.example.com/buecher" />
elements, perhaps you are looking for

//*[local-name() = 'ARTIKEL' and namespace-uri() =
'http://www.example.com/buecher']

 

[Stefan Franke]

perhaps you are looking for

//*[local-name() = 'ARTIKEL' and namespace-uri() =
'http://www.example.com/buecher']

oops, indeed I am.

Thanks very much,
Stefan

 

[Stefan Franke]

Hi,
I'm still having troubles with XPath and namespaces.

The XML I'm using looks like this:

<SAMMLUNG
xmlns:buch="http://www.example.com/buecher"
xmlns:cd="http://www.example.com/cds">

<buch:ARTIKEL Status="vorhanden">
<buch:TITEL>The Marble Faun</buch:TITEL>
<buch:AUTOR>Nathaniel Hawthorne</buch:AUTOR>
<buchREIS>10.95</buchREIS>
</buch:ARTIKEL>
<cd:ARTIKEL>
<cd:TITEL>Violinkonzerte 1, 2 und 3</cd:TITEL>
<cd:KOMPONIST>Mozart</cd:KOMPONIST>
<cdREIS>16.49</cdREIS>
</cd:ARTIKEL>
</SAMMLUNG>


If I want to display e.g. all the CDs of Mozart, I would do something like
this if I wouldn't have to deal with namespaces:

string(//*/TITEL[following-sibling::KOMPONIST='Mozart'])

My suggestion when dealing with namespaces would be something like this (but
it doesn't work, as there is no TITEL-element anywhere, but I don't know how
to get it in there):

string(//*[local-name()='ARTIKEL' and
namespace-uri()='http://www.example.com/cds']/*[string(local-name()='KOMPONIST')
= 'Mozart'])

Anyway, as I said before, that doesn't work. Could someone please help me
with that?

Thanks,
Stefan

 

[Martin Honnen]

Stefan Franke wrote:

The XML I'm using looks like this:

<SAMMLUNG
xmlns:buch="http://www.example.com/buecher"
xmlns:cd="http://www.example.com/cds">

<buch:ARTIKEL Status="vorhanden">
<buch:TITEL>The Marble Faun</buch:TITEL>
<buch:AUTOR>Nathaniel Hawthorne</buch:AUTOR>
<buchREIS>10.95</buchREIS>
</buch:ARTIKEL>
<cd:ARTIKEL>
<cd:TITEL>Violinkonzerte 1, 2 und 3</cd:TITEL>
<cd:KOMPONIST>Mozart</cd:KOMPONIST>
<cdREIS>16.49</cdREIS>
</cd:ARTIKEL>
</SAMMLUNG>


If I want to display e.g. all the CDs of Mozart, I would do something like
this if I wouldn't have to deal with namespaces:

string(//*/TITEL[following-sibling::KOMPONIST='Mozart'])

Not really, if you apply the string function to a nodeset then you get
the string value of the first node in document order so the above
doesn't give you all CD titles but only one.

My suggestion when dealing with namespaces would be something like this (but
it doesn't work, as there is no TITEL-element anywhere, but I don't know how
to get it in there):

string(//*[local-name()='ARTIKEL' and
namespace-uri()='http://www.example.com/cds']/*[string(local-name()='KOMPONIST')
= 'Mozart'])

How are you evaluating your XPaths? You should simply be able to declare
prefixes for the namespaces and then use e.g.
//prefix:TITLE
instead of going to the pain of using namespace-uri comparisons.
So I think you should better tell us about the software you are using to
evaluate XPaths and then probably someone can tell you how to use
namespace prefixes bound to namespaces when evaluating XPath expressions.

 

[Stefan Franke]

How are you evaluating your XPaths? You should simply be able to declare

prefixes for the namespaces and then use e.g.
//prefix:TITLE

Hi Martin,
I'm using FiveSight's XPathTester (Version 1.4 for Saxon - 3 December 2001).
When I try something like "//*/cd:TITEL" an error message comes up and tells
me that 'Prefix cd has not been declared'. So I thought, oh well, I have to
find a way around this problem. Am I wrong in thinking that?

regards,
Stefan

 

[Martin Honnen]

Stefan Franke wrote:

I'm using FiveSight's XPathTester (Version 1.4 for Saxon - 3 December 2001).
When I try something like "//*/cd:TITEL" an error message comes up and tells
me that 'Prefix cd has not been declared'. So I thought, oh well, I have to
find a way around this problem. Am I wrong in thinking that?

No, you need to bind that prefix to the proper namespace but an XPath
tool should give you a way to do that before evaluating an expression.
I don't know FiveSight's XPathTester and it seems it is no longer
available on their web site.
Saxon 6.5 as documented here
<http://saxon.sourceforge.net/saxon6.5.3/api-guide.html#Expressions>
has a method
declareNamespace
in its XPath API so with Java and Saxon it should be possible to bind
prfixes to namespaces before evaluating an expression.