XMLType.ToObject()

Question

Hi there,
I am running into a problem when (in Oracle9i Enterprise Edition Release 9.2.0.6.0) trying to map an XML document contained in an XMLType variable to a corresponding object-type variable using the XMLType.ToObject() function.
The problem occurs when the XML contains "repeating" fragments.
I do not know how to define the corresponding object-type in such a way that XMLType.ToObject() does not run into error "ORA-19031: XML element or attribute ... does not match any in type ...".
For example the following XML:
====================
<MyObject>
<ELEMENT01>VALUE01</ELEMENT01>
<ELEMENT02>VALUE02</ELEMENT02>
<MYGROUP>
<GROUPELEMENT01>VALUEG01E01</GROUPELEMENT01>
<GROUPELEMENT02>VALUEG01E02</GROUPELEMENT02>
</MYGROUP>
<MYGROUP>
<GROUPELEMENT01>VALUEG02E01</GROUPELEMENT01>
<GROUPELEMENT02>VALUEG02E02</GROUPELEMENT02>
</MYGROUP>
</MyObject>
====================
The corresponding object-type that I defined is as follows:
====================
create or replace type TP_MYGROUP_REC as object
(GROUPELEMENT01 varchar2(50)
,GROUPELEMENT02 varchar2(50)
create or replace type TP_MYGROUP_TAB as table of TP_MYGROUP_REC;
create or replace type TP_MYOBJECT as object
(ELEMENT01 varchar2(50)
,ELEMENT02 varchar2(50)
,MYGROUP TP_MYGROUP_TAB
====================
I tested with the following script:
====================
declare
l_xmltype xmltype;
l_myobject TP_MYOBJECT;
begin
l_xmltype := XMLTYPE
('<MyObject>
<ELEMENT01>VALUE01</ELEMENT01>
<ELEMENT02>VALUE02</ELEMENT02>
<MYGROUP>
<GROUPELEMENT01>VALUEG01E01</GROUPELEMENT01>
<GROUPELEMENT02>VALUEG01E02</GROUPELEMENT02>
</MYGROUP>
<MYGROUP>
<GROUPELEMENT01>VALUEG02E01</GROUPELEMENT01>
<GROUPELEMENT02>VALUEG02E02</GROUPELEMENT02>
</MYGROUP>
</MyObject>');
l_xmltype.ToObject(l_myobject);
end;
====================
This results in: ORA-19031: XML element or attribute GROUPELEMENT01 does not match any in type TP_MYGROUP_REC.
Does anyone out there know how to define the object-type(s) in such a way that I can cast this type of XML to an object using XMLType.ToObject() ?
Thanks a lot for your reaction,
Jaap Kool

Answer 1

In absence of an XML schema, Oracle uses a canonical mapping between SQL objects and XML.
For instance, the XML structure corresponding to the object hierarchy defined in the first post is :
<TP_MYOBJECT>
  <ELEMENT01>VALUE01</ELEMENT01>
  <ELEMENT02>VALUE02</ELEMENT02>
  <MYGROUP>
    <TP_MYGROUP_REC>
      <GROUPELEMENT01>VALUEG01E01</GROUPELEMENT01>
      <GROUPELEMENT02>VALUEG01E02</GROUPELEMENT02>
    </TP_MYGROUP_REC>
    <TP_MYGROUP_REC>
      <GROUPELEMENT01>VALUEG02E01</GROUPELEMENT01>
      <GROUPELEMENT02>VALUEG02E02</GROUPELEMENT02>
    </TP_MYGROUP_REC>
  </MYGROUP>
</TP_MYOBJECT>Note the additional "TP_MYGROUP_REC" element that encloses the two leaf values.
With that input, this works :
SQL> declare
  2    l_xmltype  xmltype;
  3    l_myobject TP_MYOBJECT;
  4  begin
  5    l_xmltype := XMLTYPE(
  6  '<TP_MYOBJECT>
  7    <ELEMENT01>VALUE01</ELEMENT01>
  8    <ELEMENT02>VALUE02</ELEMENT02>
  9    <MYGROUP>
10      <TP_MYGROUP_REC>
11        <GROUPELEMENT01>VALUEG01E01</GROUPELEMENT01>
12        <GROUPELEMENT02>VALUEG01E02</GROUPELEMENT02>
13      </TP_MYGROUP_REC>
14      <TP_MYGROUP_REC>
15        <GROUPELEMENT01>VALUEG02E01</GROUPELEMENT01>
16        <GROUPELEMENT02>VALUEG02E02</GROUPELEMENT02>
17      </TP_MYGROUP_REC>
18    </MYGROUP>
19  </TP_MYOBJECT>');
20 
21    l_xmltype.ToObject(l_myobject);
22 
23    dbms_output.put_line(l_myobject.mygroup(1).groupelement01);
24 
25  end;
26  /
VALUEG01E01
PL/SQL procedure successfully completed
Here's the approach you can follow to achieve a "custom" mapping :
{thread:id=2475819}
and,
{message:id=10712117}
Edited by: odie_63 on 20 déc. 2012 09:54