How to add an element with a namespace prefix (Part 2)

Question

Hi all,
I previously asked a question about adding an attribute with a namespace prefix to an element that already exists and that declares the namespace prefix here:
https://forums.oracle.com/thread/2610142
I received an answer that works, but now I am stumped again when I have to add an element where the element name has the namespace prefix.
For example, let's say I already have this element:
<A xmlns="namespace" xmlns:def="myns_namespace"/>
And I want to add this element:
<def:B/>
To produce this:
<A xmlns="namespace" xmlns:def="myns_namespace">
     <def:B/>
</A>
and NOT this:
<A xmlns="namespace" xmlns:def="myns_namespace">
     <def:B  xmlns:def="myns_namespace"/>
</A>
This does not work:
SELECT
xmlserialize(document
    appendChildXML(
     xmltype('<A xmlns="namespace" xmlns:def="myns_namespace"/>')
    , '/A'
    , xmlelement("def:D")
    , 'xmlns="namespace" xmlns:def="myns_namespace"'
  indent)
FROM dual;
Because of this error:
ORA-31011: XML parsing failed
ORA-19202: Error occurred in XML processing
LPX-00234: namespace prefix "def" is not declared
Error at line 1
31011. 00000 -  "XML parsing failed"
*Cause:    XML parser returned an error while trying to parse the document.
*Action:   Check if the document to be parsed is valid.
Is there any way to do this without the child element having the duplicate namespace declaration?
My oracle version is:
Oracle Database 11g Release 11.1.0.7.0 - 64bit Production

Answer 1

Hi,
This one's tricky, so tricky that I think it's not possible using Oracle built-in XML DML functions.
Even XQuery Update cannot do it (for now) because, likewise, the prefix is always redeclared at child level.
The only thing I can think of is XSLT (or maybe DOM manipulation) :
SQL> select xmlserialize(document
  2           xmltransform(
  3             xmltype('<A xmlns="namespace" xmlns:def="myns_namespace"/>')
  4           , xmltype(
  5  '<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  6     xmlns:def="myns_namespace"
  7     xmlns:ns0="namespace">
  8    <xsl:template match="ns0:A">
  9      <xsl:copy>
10        <xsl:element name="def:B"/>
11      </xsl:copy>
12    </xsl:template>
13  </xsl:stylesheet>')
14         )
15        indent
16      )
17  from dual;
XMLSERIALIZE(DOCUMENTXMLTRANSF
<A xmlns="namespace" xmlns:def="myns_namespace">
  <def:B/>
</A>