Calling ref_cursor from another PLSQL function - plsql

Question

I have three PLSQL functions: A, B and C.
The idea is this: C is calling B, B is calling A.
Function A, when it's called by B, returns a numeric value as a status indicator AND a ref cursor with tabular results.
E.g. function_A (A1 in varchar2, A2 out sys_refcursor) return number;
Function B, when it receives the results from A, is expected to reformat the results before passes them on to C, also in a form of a ref cursor.
A is an existing function and it cannot be amended, while B and C will be completely new functions.
The question is, how do I fetch the ref cursor from A? I was able to get the numeric value returned by the function (i.e the status indicator), but I have problem fetching the results of the ref cursor from A.
If I'm calling A from B, can I assume that the ref cursor of A is automatically opened?
What are the logical steps to get the results from A's ref cursor? E.g. can I fetch the results into an object type?
P/S. I have very limited programming experience and am only few months new in PLSQL.
Any hints will be much appreciated.

Answer 1

Since you have not given us the code functions, we will be based on the description of your functions.
According to the description, you have 3 functions:
Function A.
create or replace function A(A1 in varchar2, A2 out sys_refcursor) return number is
begin
open A2 for select 1 from dual;
return 2;
end;
Function B.
create or replace function B(B1 out sys_refcursor) return number is
cur sys_refcursor;
res_A number;
row_ your_table_a%rowtype;
begin
res_A := A('',cur);
loop
fetch cur into row_;
exit when cur%notfound;
--proccess with row A
end loop;
open B1 for select 2 from dual;
return 1;
end;
Function C
create or replace function C() return number is
res_B number;
cur sys_refcursor;
row_ your_table_b%rowtype;
begin
res_B:= B(cur);
loop
fetch cur into row_;
exit when cur%notfound;
--proccess with row B
end loop;
return 2;
end;

Answer 2

Maybe you can try the below snippet. Tried to replicate the scenario you mentioned in the question. Hope this helps.
CREATE OR REPLACE FUNCTION A_TEST(
A1 IN VARCHAR2,
A2 OUT sys_refcursor )
RETURN NUMBER
AS
lv_num PLS_INTEGER;
BEGIN
NULL;
OPEN a2 FOR SELECT LEVEL FROM DUAL CONNECT BY LEVEL < 19;
RETURN 1;
END;
CREATE OR REPLACE FUNCTION B_TEST
RETURN sys_refcursor
AS
lv_cur sys_refcursor;
lv_num PLS_INTEGER;
BEGIN
lv_num:=A_TEST('AV',lv_cur);
RETURN lv_cur;
END;
CREATE OR REPLACE FUNCTION C_TEST
RETURN sys_refcursor
AS
tab PLS_INTEGER;
lv_cur sys_refcursor;
BEGIN
lv_cur:=B_TEST;
LOOP
FETCH lv_cur INTO tab;
EXIT
WHEN lv_cur%NOTFOUND;
dbms_output.put_line(tab);
END LOOP;
END;