RTTI in Oracle Triggers - oracle

Question

I have this dummy types :
create or replace type Service_TY as object(
code INTEGER,
visit_analysis char(1)
)FINAL;
/
create or replace type Employee_TY as object(
dummy varchar(30)
)NOT FINAL;
/
create or replace type Doctor_TY UNDER Employee_TY(
ID INTEGER
)FINAL;
/
create or replace type Assistant_TY UNDER Employee_TY(
ID INTEGER
)FINAL;
/
create or replace type Habilitation_TY as object(
employee ref Employee_TY,
service ref Service_TY
)FINAL;
/
And these dummy tables:
CREATE TABLE Service of Service_TY(
code primary key,
visit_analysis not null check (visit_analysis in ('v', 'a'))
);
/
CREATE TABLE Doctor of Doctor_TY(
ID primary key
);
/
CREATE TABLE Assistant of Assistant_TY(
ID primary key
);
/
CREATE TABLE Habilitation of Habilitation_TY;
/
I want to create a trigger that, when a new tuple is inserted in Habilitation, should check that, if the employee is an assistant (and not a doctor), the visit_analysis attribute is equal to 'a' to know if it is a legal tuple.
I don't know how to check the type of the Employee (if it is a doctor or an assistant).
I would do something like that:
create or replace
TRIGGER CHECK_HABILITATION
BEFORE INSERT ON HABILITATION
FOR EACH ROW
DECLARE
BEGIN
IF (:NEW.EMPLOYEE is of ASSISTANT_TY)
THEN
IF :NEW.SERVICE.visit_analysis = 'v'
THEN
raise_application_error(-10000, 'invalid tuple');
END IF;
END;
But it's not working.
How should I check that type?
The error I get is:
Error(14,4): PLS-00103: Encountered the symbol ";" when expecting one of the following: if

Answer 1

Try to put it into a variable, the following one should work.
create or replace
TRIGGER CHECK_HABILITATION
BEFORE INSERT ON HABILITATION
FOR EACH ROW
DECLARE
emp employee_TY;
ser service_TY;
BEGIN
select deref(:new.employee) into emp from dual;
if (emp is of (assistant_ty)) then
select deref(:new.service) into ser from dual;
if ser.visit_analysis = 'v' then
raise_application_error('-20001', 'invalid tuple');
end if;
end if;
END;
/

Answer 2

According to the documentation for the IS OF condition, you need to wrap the type in parentheses, like:
IF (:NEW.EMPLOYEE is of (ASSISTANT_TY) )
per https://docs.oracle.com/cd/B28359_01/server.111/b28286/conditions014.htm#SQLRF52157.
I'm not really familiar with using object types so there may be some other issue that I'm not seeing.