cx_Oracle And User Defined Types

Question

Does anyone know an easier way to work with user defined types in Oracle using cx_Oracle?

For example, if I have these two types:

CREATE type my_type as object(
component   varchar2(30)
,key    varchar2(100)
,value   varchar2(4000))
/
CREATE type my_type_tab as table of my_type
/

And then a procedure in package my_package as follows:

PROCEDURE my_procedure (param  in  my_type_tab);

To execute the procedure in PL/SQL I can do something like this:

declare
  l_parms   my_type_tab;
  l_cnt     pls_integer;
begin
  l_parms := my_type_tab();
  l_parms.extend;
  l_cnt := l_parms.count;
  l_parms(l_cnt) := my_type('foo','bar','hello');
  l_parms.extend;
  l_cnt := l_parms.count;
  l_parms(l_cnt) := my_type('faz','baz','world');
  my_package.my_procedure(l_parms);
end;

However, I was wondering how I can do it in Python, similar to this code:

import cx_Oracle
orcl = cx_Oracle.connect('foo:bar@mydb.com:5555/blah' + instance)
curs = orcl.cursor()
params = ???
curs.execute('begin my_package.my_procedure(:params)', params=params)

If the parameter was a string I can do this as above, but since it's an user-defined type, I have no idea how to call it without resorting to pure PL/SQL code.

Edit: Sorry, I should have said that I was looking for ways to do more in Python code instead of PL/SQL.

Answer 1

While cx_Oracle can select user defined types, it does not to my knowledge support passing in user defined types as bind variables. So for example the following will work:

cursor.execute("select my_type('foo', 'bar', 'hello') from dual")
val, = cursor.fetchone()
print val.COMPONENT, val.KEY, val.VALUE

However what you can't do is construct a Python object, pass it in as an input argument and then have cx_Oracle "translate" the Python object into your Oracle type. So I would say you're going to have to construct your input argument within a PL/SQL block.

You can pass in Python lists, so the following should work:

components=["foo", "faz"]
values=["bar", "baz"]
keys=["hello", "world"]
cursor.execute("""
declare
  type udt_StringList is table of varchar2(4000) index by binary_integer;
  l_components udt_StringList := :p_components;
  l_keys udt_StringList := :p_keys;
  l_values udt_StringList := :p_values;
  l_parms my_type_tab;
begin
  l_parms.extend(l_components.count);
  for i in 1..l_components.count loop
    l_parms(i) := my_type(l_components(i), l_keys(i), l_values(i));
  end loop;

  my_package.my_procedure(l_parms);
end;""", p_components=components, p_values=values, p_keys=keys)

Answer 2

Are you trying to populate the table of objects more efficiently?

If you can do a SELECT, have a look at the BULK COLLECT INTO clause

Answer 3

I'm not quite sure what you mean by hard-coded, but you can build a dynamic array like this:

SQL> desc my_procedure
Parameter Type        Mode Default? 
--------- ----------- ---- -------- 
P_IN      MY_TYPE_TAB IN   

SQL> declare
  2     l_tab my_type_tab;
  3  begin
  4     select my_type(owner, table_name, column_name)
  5       bulk collect into l_tab
  6       from all_tab_columns
  7      where rownum <= 10;
  8     my_procedure (l_tab);
  9  end;
 10  /

PL/SQL procedure successfully completed

This has been tested with Oracle 11.1.0.6.