XPath and namespaces...

Discussion in 'XML' started by Stefan Franke, Jan 2, 2005.

  1. 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>
    <buch:pREIS>12.75</buch:pREIS>
    </buch:ARTIKEL>
    <cd:ARTIKEL>
    <cd:TITEL>Violinkonzert D-Dur</cd:TITEL>
    <cd:KOMPONIST>Beethoven</cd:KOMPONIST>
    <cd:pREIS>14.95</cd:pREIS>
    </cd:ARTIKEL>
    </SAMMLUNG>


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

    Thanks,
    Stefan
    Stefan Franke, Jan 2, 2005
    #1
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  2. 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>
    > <buch:pREIS>12.75</buch:pREIS>
    > </buch:ARTIKEL>
    > <cd:ARTIKEL>
    > <cd:TITEL>Violinkonzert D-Dur</cd:TITEL>
    > <cd:KOMPONIST>Beethoven</cd:KOMPONIST>
    > <cd:pREIS>14.95</cd:pREIS>
    > </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']


    --

    Martin Honnen
    http://JavaScript.FAQTs.com/
    Martin Honnen, Jan 2, 2005
    #2
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  3. > 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, Jan 2, 2005
    #3
  4. Re:still problems with XPath and namespaces...

    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>
    <buch:pREIS>10.95</buch:pREIS>
    </buch:ARTIKEL>
    <cd:ARTIKEL>
    <cd:TITEL>Violinkonzerte 1, 2 und 3</cd:TITEL>
    <cd:KOMPONIST>Mozart</cd:KOMPONIST>
    <cd:pREIS>16.49</cd:pREIS>
    </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
    Stefan Franke, Jan 3, 2005
    #4
  5. Re: still problems with XPath and namespaces...

    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>
    > <buch:pREIS>10.95</buch:pREIS>
    > </buch:ARTIKEL>
    > <cd:ARTIKEL>
    > <cd:TITEL>Violinkonzerte 1, 2 und 3</cd:TITEL>
    > <cd:KOMPONIST>Mozart</cd:KOMPONIST>
    > <cd:pREIS>16.49</cd:pREIS>
    > </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.

    --

    Martin Honnen
    http://JavaScript.FAQTs.com/
    Martin Honnen, Jan 3, 2005
    #5
  6. Re: still problems with XPath and namespaces...

    > 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
    Stefan Franke, Jan 3, 2005
    #6
  7. Re: still problems with XPath and namespaces...

    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.



    --

    Martin Honnen
    http://JavaScript.FAQTs.com/
    Martin Honnen, Jan 3, 2005
    #7
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