Re: [xml] xmllint and namespaces

[Stefan Kost <kost imn htwk-leipzig de>]

Hi Fabrice,
> Stefan Kost wrote:
>
>  > and invoked
>  > # testXPath -i share/gitk/gitkHelloUser_main.xml
>  > "//control[ id="UserName"]"
>  > Object is a Node Set :
>  > Set contains 0 nodes
>
>
>   Di you try testXPath -i share/gitk/gitkHelloUser_main.xml
> "//control[ id='UserName']"
>
dumb me. okay that fixes it there.

>  >
>  > Finaly about "xmlXPathNewContext()", when I had been using a namespace
>  > with a
>  > prefix I was using
>  >       ctxt->namespaces=g_new(xmlNsPtr,1);
>  >       ctxt->namespaces[0]=mynamespace;
>  >       ctxt->nsNr=1;
>  > before using the context. Now that namespace has a "ns->prefix==NULL",
>  > should I
>  > still attach it or better use
>  >       ctxt->namespaces=NULL;
>  >       ctxt->nsNr=0;
>  > It seems to make no difference. I don't use "xmlXPathRegisterNs()" as
>  > there is
>  > no version of it accepting a xmlNsPtr.
Okay now I use
                if(!xmlXPathRegisterNs(ctxt,elements->ns->prefix,elements->ns->href)) {
        gitk_log("  before xmlXPathCompiledEval()");
        result=xmlXPathCompiledEval(xpath_expression,ctxt);
        xmlXPathRegisteredNsCleanup(ctxt);
}

DANIEL: there is a typo in the API docs about "xmlXPathRegisteredNsCleanup()"
I guess it frees all memory allocated by previous xmlXPathRegisterNs() calls.

> Stephan,
>
>   I'm using the XPath support of libxml in lots of programs and never
> had any problem. Since XPath has no notion of a default namespace, you
> *MUST* bind every namespace used in your queries to a prefix, even if
> you are using a default namespace declaration in the instance. Of course
> this prefix can be different from the one used in your document. If you
> follow these simple rules you'd be OK. I'm always using
> xmlXPathRegisterNs() to add my namespace binding into the XPath engine,
> and use these prefix in my expressions. Works like a charm.

You mean I can use a document *without namespaceprefixes, but with a default ns 
such as
<giml xmlns="http://gitk.sourceforge.net/";>
  <context/>
</giml>

and when doing a query I register a ns={prefix="q",href="http://gitk.sf.net/"} 
and writing my query as e.g. "//q:context"?

Stefan
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