Why must I call DBMS_XDB.cfg_get() to avoid ORA-19030 error?

Question

I am getting error: "ORA-19030: Method invalid for non-schema based XML Documents" when trying to validate an XML document. I'm on Oracle 10.2.0.4.0.
If I log on to Oracle and execute the following anonymous block:
declare
l_xml XMLTYPE;
tempXML XMLTYPE;
BEGIN
SELECT XMLTYPE (xml_data)
INTO l_xml
FROM pr_interactive_import
WHERE interactive_import_id = 1440;
tempXML := l_xml.createSchemaBasedXML ();
tempXML.schemavalidate ();
END;
Then I receive the above error. Note that table pr_interactive_import has a valid XML document for the specified record. However, if I issue:
select DBMS_XDB.cfg_get()
from dual;
from the same session and then execute the anonymous block above, the xml document correctly validates.
Some time ago I had modified xdbconfig.xml so that Oracle would properly resolve XML documents (stored in this table) to their registered schemas as the documents in question did not specify a schemaLocation attribute. My question though, is why do I have to call DBMS_XDB.cfg_get() every time I start a new session in order to validate these XML documents as in the code above? As far as I know there is only one xdbconfig.xml in the system, so I would expect it to be loaded or looked up automatically when calling schemavalidate().
Is there a database setting that would load xdbconfig.xml for all sessions when they connected? Or am I missing something obvious?
Thanks,
Alan

Answer 1

You have a point, however the design was simply not intended to work that way. The createSchemaBasedXML function is designed to allow the developer to cast the XML Instance to a speciofied XML Schema. It was not designed to try to determine what the XML schema in question is...
That said you could write a PL/SQL function that would use the mapping infromation in xdbConfig to cast the XML schema...
SQL> create or replace package XMLSCHEMA_UTILITIES
  2  as
  3    function createSchemaBasedXML(P_XML XMLTYPE) return XMLType;
  4  end;
  5  /
Package created.
SQL> show errors
No errors.
SQL> --
SQL> create or replace package body XMLSCHEMA_UTILITIES
  2  as
  3  function createSchemaBasedXML(P_XML XMLTYPE)
  4  return XMLType
  5  as
  6    V_SBXML XMLType;
  7    V_SLH   VARCHAR2(700);
  8  begin
  9    select XMLCAST
10           (
11             XMLQuery
12             (
13               'declare default element namespace "http://xmlns.oracle.com/xdb/xdbconfig.xsd"; (: :)
14                for $i in $CFG/xdbconfig/sysconfig/schemaLocation-mappings/schemaLocation-mapping[element=fn:local-name($XML) and namespace=fn:namespace-uri($XML)]/schemaURL
15                return $i'
16               passing dbms_xdb.cfg_get() as "CFG",
17               P_XML as "XML"
18               returning content
19             )
20             as VARCHAR2(700)
21           )
22      into V_SLH
23      from dual;
24
25    return P_XML.createSchemaBasedXML(V_SLH);
26  end;
27  --
28  end;
29  /
Package body created.