RE: XmlDocument.SelectSingleNode XPathException

Hi;

I agree with everything you said except...

The "xmlns:sns="http://www.test.org/sub";>" in the xml itself provides the
necessary information to turn:
//sns:subItem[@sid="11"]
into:
//http://www.test.org/sub:subItem[@sid="11";]

That's how java parsers like dom4j handle it.

And in fact, it would be very weird if I could pass in xml with
"xmlns:sns="http://www.test.org/sub";>" in it and then call
mgr.AddNamespace("sns","http://www.dave.com";); and then I would have changed
the meaning of the xml from what is set in it's own header.

Am I missing something here?

thanks - dave



"Steven Cheng[MSFT]" wrote:

> Hi Dave,
>
> Thanks for your followup.
> As for using XmlNamespaceManager to help executing XPATH in xmldocument
> which contains namespace/prefix, I don't think it's the limitation of
> .net's XML interfaces. I'm sure this is a quite reasonable feature, here is
> the reason why the XmlNamespaceManager is necessary:
>
> When there is namespace in an xml document to scope elements in different
> area(schemas), we use prefixs to identify namespaceURI. Like:
>
> ===============================
> <?xml version="1.0" encoding="utf-8" ?>
> <root xmlns="http://www.test.org";
> xmlns:sns="http://www.test.org/sub";>
> <data>
> <items>
> <item id="1">
> <sns:subItem sid="11">
>
> </sns:subItem>
> <sns:subItem sid="12">
>
> </sns:subItem>
> </item>
> </items>
> </data>
> </root>
> ==============================
>
> when we need to quer the <sns:subItem sid="11">
>
> maybe we'll think that use the following xpath is quite normal:
>
> //sns:subItem[@sid="11"]
>
> However, according to the W3C XPATH1.0 specification. The full qualified
> name of an element is actually it's namespaceURI(not prefix) combined with
> its localname, that means the above path should be:
>
> //http://www.test.org/sub:subItem[@sid="11";]
>
> And as we known, namespace prefix is just a alias of namespaceURI, which
> can be replaced by any other one as long as it can uniquely identity that
> namespaceURI in the document. So .net framework provide the
> XmlNamespaceManager which can help specify Namespace with arbitary prefix
> value. For example, the above selection can be replaced by
>
> XmlNamespaceManager mgr = new XmlNamespaceManager(new NameTable());
>
> mgr.AddNamespace("aaa","http://www.test.org/sub";);
>
> string xpath = "//aaa:subItem[@sid='11']";
>
> "sns" is just an alias, the actual idenitfy is "http://www.test.org/sub";,
> and the prefix in xpath should be able to be replaced by another alias.
> (not only limited to "sns")
>
> I'm not sure if those JAVA xml api is capable of this. However, at least I
> think using prefix directly in xpath without any mapping info between
> prefix---namespaceURI is not a reasonable behavior. Also, some times we're
> not executing Xpath on a whole XmlDocument, just on a XmlNode , then where
> does the API to look for the namespace /prefix declaration on the fly?
> That's also why the .net using the XmlNamespaceManager to specify the
> prefix---namespaceURI mapping.
>
> #HOW TO: Specify Namespaces When You Use an XmlDocument to Execute XPath
> Queries in Visual C# .NET
> http://support.microsoft.com/default.aspx?scid=kb;en-us;318545
>
> If you still have anything unclear, please feel free to post here. Thanks,
>
> Steven Cheng
> Microsoft Online Support
>
> Get Secure! www.microsoft.com/security
> (This posting is provided "AS IS", with no warranties, and confers no
> rights.)
>
>
>
>
>
.

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