How to add namespace prefixes to XMLType created from Object?

Question

Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE 11.2.0.3.0 Production
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production
I'm working with SOAP request creation from Schema derived Types.
Consider the registration of the following annotated schema (I wanted Oracle to create the types for me, but with my own names):
exec dbms_xmlschema.deleteSchema(schemaURL => 'Parameters4.xsd');
declare
v_xsd xmltype := xmltype('<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:oraxdb="http://xmlns.oracle.com/xdb"
           xmlns = "http://www.cognera.com"
           targetNamespace = "http://www.cognera.com">
  <xs:element name="Parameters" oraxdb:SQLName="Parameters" oraxdb:SQLType="Parameters">
    <xs:complexType oraxdb:SQLType="Parameters">
      <xs:sequence>
        <xs:element name="Param1" type="xs:string" oraxdb:SQLName="Param1" oraxdb:SQLType="VARCHAR2" />
        <xs:element name="NestedItems" oraxdb:SQLName="NestedItems" oraxdb:SQLType="NestedItemsType">
          <xs:complexType oraxdb:SQLType="NestedItemsType">
            <xs:sequence>
              <xs:element name="NestedItem" type="NestedItemType" oraxdb:SQLName="NestedItem" oraxdb:SQLType="NestedItemType"/>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:complexType name="NestedItemType" oraxdb:SQLType="NestedItemType">
    <xs:sequence>
      <xs:element name="nParam1" type="xs:string" oraxdb:SQLName="nParam1" oraxdb:SQLType="VARCHAR2"/>
      <xs:element name="nParam2" type="xs:string" oraxdb:SQLName="nParam2" oraxdb:SQLType="VARCHAR2"/>
      <xs:element name="nParam3" type="xs:string" oraxdb:SQLName="nParam3" oraxdb:SQLType="VARCHAR2"/>
    </xs:sequence>
  </xs:complexType>
</xs:schema>
begin
  dbms_xmlschema.registerSchema(schemaURL => 'Parameters4.xsd', --this name is local to each ERS schema.                                
                                      schemaDoc => v_xsd,
                                      local => TRUE,
                                      genTypes => TRUE, --only want the types
                                      genbean => FALSE,
                                      genTables => TRUE, --not sure if I need this
                                      force => TRUE,
                                      owner => user);
end;
Types created were:
CREATE OR REPLACE TYPE "NestedItemType" AS OBJECT ("SYS_XDBPD$" "XDB"."XDB$RAW_LIST_T","nParam1" VARCHAR2(4000 CHAR),"nParam2" VARCHAR2(4000 CHAR),"nParam3" VARCHAR2(4000 CHAR))NOT FINAL INSTANTIABLE
CREATE OR REPLACE TYPE "NestedItemsType" AS OBJECT ("SYS_XDBPD$" "XDB"."XDB$RAW_LIST_T","NestedItem" "NestedItemType")FINAL INSTANTIABLE
CREATE OR REPLACE TYPE "Parameters" AS OBJECT ("SYS_XDBPD$" "XDB"."XDB$RAW_LIST_T","Param1" VARCHAR2(4000 CHAR),"NestedItems" "NestedItemsType")FINAL INSTANTIABLE
I found that in order to build these types using constructors (to avoid PLS-00306: wrong number or types of arguments in call to 'NestedItemType'), that I needed to edit these types (drop the xdb magic):
CREATE OR REPLACE TYPE "NestedItemType" AS OBJECT ("nParam1" VARCHAR2(4000 CHAR),"nParam2" VARCHAR2(4000 CHAR),"nParam3" VARCHAR2(4000 CHAR))FINAL INSTANTIABLE
CREATE OR REPLACE TYPE "NestedItemsType" AS OBJECT ("NestedItem" "NestedItemType")FINAL INSTANTIABLE
CREATE OR REPLACE TYPE "Parameters" AS OBJECT ("Param1" VARCHAR2(4000 CHAR),"NestedItems" "NestedItemsType")FINAL INSTANTIABLE
I read on the forums of a hack to get a namespace added in the output:
CREATE OR REPLACE TYPE "Parameters" AS OBJECT ("@xmlns" VARCHAR2(4000), -- namespace attribute HACK
                                                       "Param1" VARCHAR2(4000 CHAR),"NestedItems" "NestedItemsType")FINAL INSTANTIABLE
Putting it all together, I have:
DECLARE
  v_Parameters    "Parameters";
  v_xml           xmltype;
  v_print_output  clob;     
begin
  v_Parameters :=  "Parameters"('www.cognera.com',
                                'hello',
                              "NestedItemsType"("NestedItemType"('one',
                                                             'two',
                                                             'three'
  v_xml := xmltype(xmlData => v_Parameters);
  select xmlserialize(document
                      xmlquery('declare namespace soap = "http://www.w3.org/2003/05/soap-envelope";                                                             
                                declare namespace cognera = "http://www.cognera.com";
                                <soap:Envelope>
                                   <soap:Header/>
                                   <soap:Body>
                                   </soap:Body>
                                 </soap:Envelope>
                               ' passing v_xml returning content) as clob
                      indent size=2
                     ) into v_print_output from dual;
  dbms_output.put_line(v_print_output);
end;
This outputs:
<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope">
  <soap:Header/>
  <soap:Body>
    <Parameters xmlns="www.cognera.com">
      <Param1>hello</Param1>
      <NestedItems>
        <NestedItem>
          <nParam1>one</nParam1>
          <nParam2>two</nParam2>
          <nParam3>three</nParam3>
        </NestedItem>
      </NestedItems>
    </Parameters>
  </soap:Body>
</soap:Envelope>
What I really want is:
<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:c="www.cognera.com">
  <soap:Header/>
  <soap:Body>
    <c:Parameters>
      <c:Param1>hello</c:Param1>
      <c:NestedItems>
        <c:NestedItem>
          <c:nParam1>one</c:nParam1>
          <c:nParam2>two</c:nParam2>
          <c:nParam3>three</c:nParam3>
        </c:NestedItem>
      </c:NestedItems>
    </c:Parameters>
  </soap:Body>
</soap:Envelope>
How do I do this without having to programatically add the namespace using a custom XQuery function?

Answer 1

See this similar thread, it should give you some better alternatives than the "@xmlns" hack :
Add Namespaces via XQuery to an XML Instance
For example :
SQL> SELECT XMLSerialize(DOCUMENT
  2           XMLTransform(
  3             xmltype(
  4               "Parameters"('hello', "NestedItemsType"("NestedItemType"('one','two','three')))
  5             )
  6           , xmlparse(content
  7  '<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  8    <xsl:output encoding="UTF-8" indent="yes" method="xml"/>
  9    <xsl:param name="ns"/>
10    <xsl:template match="/">
11      <soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope">
12        <soap:Header/>
13          <soap:Body>
14               <xsl:apply-templates select="*"/>
15             </soap:Body>
16         </soap:Envelope>
17    </xsl:template>
18    <xsl:template match="*">
19      <xsl:element name="{local-name()}" namespace="{$ns}">
20        <xsl:apply-templates select="@*|node()"/>
21      </xsl:element>
22    </xsl:template>
23  </xsl:stylesheet>')
24           , q'{ns="'www.cognera.com'"}'
25           )
26           INDENT
27         ) AS "XSLT Output"
28  FROM dual ;
XSLT Output
<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope">
  <soap:Header/>
  <soap:Body>
    <Parameters xmlns="www.cognera.com">
      <Param1>hello</Param1>
      <NestedItems>
        <NestedItem>
          <nParam1>one</nParam1>
          <nParam2>two</nParam2>
          <nParam3>three</nParam3>
        </NestedItem>
      </NestedItems>
    </Parameters>
  </soap:Body>
</soap:Envelope>
You can store the stylesheet in the XDB repository or in a table and access it using a DBUriType.
It then provides a concise way to both add the namespace and wrap the payload in the envelope.