Adding namespace qualified element nodes

Question

Is there a way to add namespace qualified element nodes to
a document stored in a BDBXML container using the XmlModify class
(BDBXML version 2.3.10, Linux)? Or, for that matter, any other
handles?
Particularly, is it possible to achieve this using the PHP
extension?
Let me give an example.
When doing queries, you can set a namespace in the XmlQueryContext
or in the XQuery expression itself:
# prefix cannot be '' as of BDBXML 2.3.10
$qc->setnamespace('a', 'http://as-guides.com/wev1');
declare namespace a = "http://as-guides.com/wev1"; ...
declare default element namespace "http://as-guides.com/wev1"; ...
You can then refer to your namespace qualified elements as "a:Bla"
etc. Or just as "Bla" if you make your namespace the default
namespace.
So far, so good.
Now what if I want to add a namespace qualified element to
my document? However I go about setting the namespace I always end
up with either an apparently namespace qualified element which the
namespace is not registered for or an element in the empty
namespace.
What I want is my element to adhere to the namespace
"http://as-guides.com/wev1", which is set as the default
element namespace in my document.
Here is an example document.
<Broadcast xmlns="http://as-guides.com/wev1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://as-guides.com/wev1 ds.xsd">
<Start epoch="1186100400">2007-08-03T00:20:00Z</Start>
<End epoch="1186100700">2007-08-03T00:25:00Z</End>
<Content>
<Title>Tagesschau</Title>
<Genre>Nachrichten</Genre>
</Content>
</Broadcast>
And here is my PHP code.
$docname = '2007-08-02-1186100400-25758173-ard.xml_41368';
$mgr = new xmlmanager;
$cont = $mgr->opencontainer($argv[1]);
$cont->addalias('tv');
$qc = $mgr->createquerycontext();
$qc->setnamespace('a', 'http://as-guides.com/wev1');
$qexp = $mgr->prepare('/a:Broadcast', $qc);
$mod = $mgr->createmodify();
$mod->addappendstep($qexp, XmlModify_Element, 'a:now', time());
$doc = $cont->getdocument($docname);
$docval = new xmlvalue($doc);
echo $docval->asString(), "\n";
$uc = $mgr->createupdatecontext();
$mod->execute($docval, $qc, $uc);
Here is what gets added as last child node under "Broadcast":
<a:now xmlns="">1189605065</a:now>
So the namespace prefix I specified is added verbatim, without
regard to the namespace settings in $qc (XmlQueryContext) - which
do work fine for the query. No namespace declaration for "a"
is added to the document. The resulting XML is invalid, as
xmllint correctly points out.
namespace error : Namespace prefix a on now is not defined
So settings in XmlQueryContext do not seem to have any bearing on
my update. XmlUpdateContext, on the other hand, does not have any
methods defined for setting the namespace.
Not setting the namespace in $qc (XmlQueryContext) and specifying
it in the XQuery itself didn't work either. I left out the call to
"setnamespace()" and changed the query to:
declare default element namespace "http://as-guides.com/wev1";
/Broadcast
And I changed "a:now" to just "now". Here is what got added:
<now xmlns="">1189607498</now>
I didn't expect this second version to work, but I did expect the first
one to work.
What is the meaning of supplying XmlQueryContext to the execute()
method?
Is there a way to add namespace qualified elements to a document?
If so, how can it be done?

Answer 1

Thanks for your answer, George. I haven't quite understood how to make it do the trick, though.
To change one document I did:
dbxml> open tv.dbxml
dbxml> setnamespace a http://as-guides.com/wev1
Binding a -> http://as-guides.com/wev1
dbxml> getdoc 2007-08-02-1186104300-25758380-sat1.xml_40564
1 documents found
dbxml> print
<?xml version="1.0" encoding="UTF-8"?>
<Broadcast xmlns="http://as-guides.com/wev1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://as-guides.com/wev1 ds.xsd">
<Start epoch="1186104300">2007-08-03T01:25:00Z</Start>
<End epoch="1186105800">2007-08-03T01:50:00Z</End>
<VPS>03:25</VPS>
<Content>
<Title>Moin</Title>
</Content>
</Broadcast>
dbxml> append doc(2007-08-02-1186104300-25758380-sat1.xml_40564)/a:Broadcast element "" "<a:now xmlns:a='http://as-guides.com/wev1'>NOW</a:now>"
Appending into nodes: doc(2007-08-02-1186104300-25758380-sat1.xml_40564)/a:Broadcast an object of type: element with name: and content: <a:now xmlns:a='http://as-guides.com/wev1'>NOW</a:now>
0 modifications made.
No change made to my document. I used the doc() function instead of collection() as in the example you gave. Using collection() as in your example (verbatim) I get an error message:
stdin:17: append failed, Error: XmlModify::execute: Cannot perform a modification on an XmlValue that isn't either Node or Document type
This is in the FAQ, but I don't quite get it.
http://www.oracle.com/technology/products/berkeley-db/faq/xml_faq.html#49
Anyway, I can still perform modifications outside of the container and then replace the document. Or wait till 2.4.
Thanks for your answer and the good work. Regards,
Michael