Namespaces & .NET XPaths

[Steve Robinson]

Just out of interest - is there an easier/quicker way to retrieve values via
Xpath when namespaces are used?

At the moment I seem to need a lot more lines of code to do something I
thought was fairly standard? Of course I can just wrap the calls up into a
helper function but was wondering if there was an easier way...

XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);

nsmgr.AddNamespace("xs", http://mynamespace.com);

node = doc.SelectSingleNode("//xs:person",nsmgr);

... pluck from node...

OR

XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);

nsmgr.AddNamespace("xs", http://mynamespace.com);

xpExp = nav.Compile("string(//xs:person/@name)");

xpExp.SetContext(xmlNSM);

string name = nav.Evaluate(xpExp).ToString(); (BTW: is ToString()
any different to casting (string) )

[Oleg Tkachenko]

Steve Robinson wrote:

Just out of interest - is there an easier/quicker way to retrieve values via
Xpath when namespaces are used?

If you mean using NamespaceManager - no, you cannot avoid using it when
seleting namespaced nodes, unless your XPath expression is
namespace-prefix-neutral, like
//*[local-name='person' and namespace-uri()='http://mynamespace.com']
instead of
//xs:person

And in fact I don't see any problem with using NamespaceManager - anyway
must be some way to say what xs namespace prefix you are using points
to, becuase arbitrary XML doc may declare xs namespace prefix twice,
each time binding it to a different namespace URI's:
<xs:foo xmlns:xs="foo">
<xs:bar xmlns:xs="bar">blah</xs:bar>
</xs:foo>
--
Oleg Tkachenko
http://www.tkachenko.com/blog
Multiconn Technologies, Israel

[Steve Robinson]

I guess I just hate having to compile an expression when I do an Evaluate
rather than Select.

XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);
nsmgr.AddNamespace("xs", http://mynamespace.com);
xpExp = nav.Compile("string(//xs:person/@name)");
xpExp.SetContext(xmlNSM);
string name = (string) nav.Evaluate(xpExp);

if I need to pull another value out I need to compile a new expression,
setcontext and Evaluate again...and so on...

xpExp = nav.Compile("string(//xs:person/@department)");
xpExp.SetContext(xmlNSM);
string department = (string) nav.Evaluate(xpExp);

I could always wrap it all up in helper functions or a class, but Ideally it
would have been good if I could at least reuse the same expression object
and just the path or SetContext() would remain valid -

nav.SetContext(namespace); // set namespace for xpath
val1 = nav.Evaluate();
val2 = nav.Evaluate();


"Oleg Tkachenko" <oleg@NO_SPAM_PLEASEtkachenko.com> wrote in message
news:%2***************@TK2MSFTNGP11.phx.gbl...

Steve Robinson wrote:

Just out of interest - is there an easier/quicker way to retrieve values via Xpath when namespaces are used?

If you mean using NamespaceManager - no, you cannot avoid using it when
seleting namespaced nodes, unless your XPath expression is
namespace-prefix-neutral, like
//*[local-name='person' and namespace-uri()='http://mynamespace.com']
instead of
//xs:person

And in fact I don't see any problem with using NamespaceManager - anyway
must be some way to say what xs namespace prefix you are using points
to, becuase arbitrary XML doc may declare xs namespace prefix twice,
each time binding it to a different namespace URI's:
<xs:foo xmlns:xs="foo">
<xs:bar xmlns:xs="bar">blah</xs:bar>
</xs:foo>
--
Oleg Tkachenko
http://www.tkachenko.com/blog
Multiconn Technologies, Israel

[Oleg Tkachenko]

Steve Robinson wrote:

I guess I just hate having to compile an expression when I do an Evaluate
rather than Select.

Well, I tend to agree with you, but... Let's wait PDC and see what they have
prepared in V2 API for us.
--
Oleg Tkachenko
http://www.tkachenko.com/blog
Multiconn Technologies, Israel