How can i use REF type in PL/SQL Oracle? - oracle

Question

I have this code :
CREATE OR REPLACE TYPE t_abonnement_type AS OBJECT
(
ref_abonnement_type NUMBER,
type_abonne VARCHAR(50),
MEMBER PROCEDURE DISPLAY
);
CREATE OR REPLACE TYPE t_abonnement AS OBJECT
(
ref_abonnement NUMBER,
date_debut DATE,
type_abonnement REF t_abonnement_type,
MEMBER PROCEDURE DISPLAY
);
What i want to do is just create the members procedures DISPLAY declared.
So i did it this way :
CREATE OR REPLACE TYPE BODY t_abonnement AS
MEMBER PROCEDURE DISPLAY IS
BEGIN
/* SOME CODE */
type_abonnement.display;
END;
END;
And i get this error
PLS-00536: Navigation through REF variables is not supported in PL/SQL.
So how can i deal with REF in PL/SQL statements ?
Thanks

Answer 1

As mentioned by #APC, it's not possible to directly use member function of a Object to another using REF since Oracle supports them in SQL but not in PL/SQL.
However if I look at your requirement from a different angle, I could see you are trying to simply make use of Procedure used in an Object to another Object. Means if I forget the referencing part and create a scenario which could satisfy the referencing concept then it should "OK".
This is possible. Yes..!!! This can be done. The only thing I did here is to make the two Objects as parent-child to achieve referencing. See demo below:
--Parent Object
CREATE OR REPLACE TYPE t_abonnement_type AS OBJECT
(
ref_abonnement_type NUMBER,
type_abonne VARCHAR(50),
MEMBER FUNCTION DISPLAY return varchar2
) NOT FINAL;
-- Member Funtion Body
CREATE OR REPLACE TYPE BODY t_abonnement_type
AS
MEMBER FUNCTION DISPLAY
return varchar2
IS
BEGIN
return ('Hi');
END DISPLAY;
END;
Testing my Parent Object:
SQL> SELECT t_abonnement_type(1,'a').display() col from DUAL;
COL
---
Hi
Child Object to achieve referencing concept
CREATE OR REPLACE TYPE t_abonnement
under t_abonnement_type
(
ref_abonnement NUMBER,
date_debut DATE,
MEMBER function V_DISPLAY return varchar2
);
--Member function
CREATE OR REPLACE TYPE BODY t_abonnement
AS
MEMBER Function V_DISPLAY return varchar2
IS
var varchar2(10);
BEGIN
var:= t_abonnement_type(1,'A').display(); --Calling Parent Member function here
return('Called from Child Object -->'||var);
END;
END;
Testing my Child Object to check if the parent Member function is referenced or not:
SQL> SELECT T_ABONNEMENT(1,'A',2,TO_DATE('30-JUN-2018','DD-MON-YYYY')).V_DISPLAY() COL FROM DUAL;
Col
---
Called from Child Object -->Hi
Note I haven't used overloading done in your code as I feel overloading makes the stuff harder to understand as an individual as well as for compiler.