Passing a generic rowtype, convert to XML

Question

We're currently storing some data in a XMLType column. For the originally intended purpose, we had access to a dynamic SQL statement, via a refcursor and so we've been able to use DBMS_SQL to retrieve column names from those SQL statements. Then we convert that into XML and store it in the XMLType column.
Now we're considering letting other processes use this code, but they'll be working off of a different mechanism which generates their own SQL statements. But we were looking for a generic mechanism to build the same XML data from, best case scenario, a ROWTYPE variable. But everything I've read tells me I at least need a SQL statement (refcursor included) in order to have access to the elements on the row. And I'm trying to steer clear of passing in the SQL statement, since some of this calling code is working off of cursor for loops.
We're trying to ultimately build something like:
create function BUILD_XML (p_generic_rowtype SYSROWTYPE) return varchar2
as
  for each column in p_generic_rowtype
  loop
    build_another_line_of_xml_code;  
  end loop;
  return xml;
end;
We know the myriad of calling programs will have a ROWTYPE variable available, but we won't know anything about it. I
've also thought about building something where a name-value paired collection is passed in, but I still think that's going to require something more manual on the calling program's end. Mostly I'm just trying to see if there's a concise way to get this working, or if we would need to either pass in a SQL stmt or customize the calling code every time.
--=Chuck

Answer 1

Have you considered using a standard 'generic' column type and a fixed number of columns? That is what Oracle uses for DML error logging tables
EXEC DBMS_ERRLOG.CREATE_ERROR_LOG ('EMP')
SELECT DBMS_METADATA.GET_DDL('TABLE', 'ERR$_EMP', 'SCOTT') FROM DUAL
CREATE TABLE "SCOTT"."ERR$_EMP"
( "ORA_ERR_NUMBER$" NUMBER,
"ORA_ERR_MESG$" VARCHAR2(2000),
"ORA_ERR_ROWID$" UROWID (4000),
"ORA_ERR_OPTYP$" VARCHAR2(2),
"ORA_ERR_TAG$" VARCHAR2(2000),
"EMPNO" VARCHAR2(4000),
"ENAME" VARCHAR2(4000),
"JOB" VARCHAR2(4000),
"MGR" VARCHAR2(4000),
"HIREDATE" VARCHAR2(4000),
"SAL" VARCHAR2(4000),
"COMM" VARCHAR2(4000),
"DEPTNO" VARCHAR2(4000)
Every column is a VARCHAR2(4000). You could use a standard column naming convention and then use a %ROWTYPE on the table (or on a view).
Since your use case is email everything needs to be converted to test anyway so could easily be stored in such a table.