How to reference a custom type string in a trigger

Question

In SQL, I created 2 user types. The first is just a minimal type, for a brief example.

CREATE OR REPLACE TYPE TestType FORCE AS OBJECT
(
    title VARCHAR(50)
);
/

The second type is the log type of the first type. This type is used to record changes of the first type.

CREATE OR REPLACE TYPE LogType FORCE AS OBJECT 
(
  title VARCHAR(50),
  TestRef REF TestType
);
/

And tables:

CREATE TABLE TestTable OF TestType;
CREATE TABLE LogTable OF LogType;

Trigger:

CREATE TRIGGER UpdateLog
BEFORE UPDATE OF title ON TestTable
REFERENCING new as newrow old as oldrow
FOR EACH ROW
WHEN (newrow.title != oldrow.title)
BEGIN
  INSERT INTO LogTable VALUES(:oldrow.title, :newrow);
END UpdateLog;
/  

Now, as mentioned earlier, I would like to have a trigger on TestTable that will monitor row changes. The next part works, the problem occurs when I want to insert changes into the log table. Inserting zero instead of help works, but trying to insert something similar: newrow or ref (: newrow) does not. It throws an invalid bind variable (PLS-00049).

So the question is, how do I reference newrow in the log table?

Answer 1

MAKE_REF OBJECT_ID:

CREATE OR REPLACE TRIGGER UpdateLog
BEFORE UPDATE OF title ON TestTable
REFERENCING new as newrow old as oldrow
FOR EACH ROW
WHEN (newrow.title != oldrow.title)
BEGIN
  INSERT INTO LogTable VALUES(:oldrow.title, make_ref(TestTable, :newrow.object_id));
END UpdateLog;
/