PostgreSQL: ERROR: $name$ is not a scalar variable - function

Question

There is a function that returns 3 parameters one of which is a composite type:
CREATE OR REPLACE FUNCTION f1(
p_text text,
OUT result_status_id smallint,
OUT result_status_msg text,
OUT result_my_type my_type
)
RETURNS record AS
$BODY$
--body here
$BODY$
LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER
COST 100
The composite type my_type looks like following:
CREATE TYPE my_type AS
(d_real real,
d_int1 integer,
d_int2 integer,
d_int3 integer,
d_int4 integer,
d_int5 integer,
d_int6 integer,
d_int7 integer,
d_int8 integer,
d_int9 integer,
d_int10 integer,
d_bool boolean,
d_date date,
d_text text
);
There is another function f2 that calls function f1 in its body:
CREATE OR REPLACE FUNCTION f2(
p_text text
)
RETURNS record AS
$BODY$
DECLARE
l_status_id smallint;
l_status_msg text;
l_my_type my_type;
BEGIN
--some logic here
--this statement fails
SELECT * FROM f1(p_text) 'x'
INTO l_status_id, l_status_msg, l_my_type;
--logic continues here
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER
COST 100;
The problem is that when executing sql with the function I receive the following error:
ERROR: "l_my_type" is not a scalar variable
How may one get a composite type object from another function?

Answer 1

You are violating the rules. The manual:
where target can be a record variable, a row variable, or a
comma-separated list of simple variables and record/row fields.
A record or row variable cannot be part of multiple-item INTO list.
One way around this:
CREATE OR REPLACE FUNCTION f2(p_text text)
RETURNS record AS
$BODY$
DECLARE
r record;
l_status_id smallint;
l_status_msg text;
l_my_type my_type;
BEGIN
SELECT *
FROM f1(p_text) x -- don't single quote 'x'
INTO r;
l_status_id := r.result_status_id;
l_status_msg := r.result_status_msg;
l_my_type := r.result_my_type;
RETURN r; -- or whatever ..
END;
$BODY$
LANGUAGE plpgsql VOLATILE;
There are more ways. Depends where you are going with this. I hardly ever return an anonymous record.

Answer 2

Composite types in tuples are one of those things which is supported partially and you run into odd issues (particularly with thins like storage but that's a story for another time). One way you could accomplish this is:
CREATE TYPE return_type_for_function AS (
result_status_id smallint,
result_status_msg text,
result_my_type my_type
);
CREATE FUNCTION myfunc(....) RETURNS return_type_for_function ....
This is the way I have always done it. This is a little more mature than using OUT variables.
Here's a trivial example:
or_examples=# create table rel_examples.tabletest (id int);
CREATE TABLE
or_examples=# create table comp_table_test (test rel_examples.tabletest);
CREATE TABLE
or_examples=# create function test(int) returns comp_table_test
immutable language sql as $$
select row(row($1))::comp_table_test; $$;
CREATE FUNCTION
or_examples=# select test(1);
test
---------
("(1)")
(1 row)

Answer 3

However, #Chris Travers has proposed an acceptable solution, in my case it was unfortunately not possible to introduce a new type for returning data from f1 function.
Nevertheless, one may call the function f1() in the function f2() and still get the data using the following syntax:
CREATE OR REPLACE FUNCTION f2(
p_text text
)
RETURNS record AS
$BODY$
DECLARE
l_status_id smallint;
l_status_msg text;
l_my_type my_type;
l_record record;
BEGIN
--some logic here
--this statement is okay now
l_record = f1(p_text);
l_status_id = l_record.result_status_id;
l_status_msg = l_record.result_status_msg;
l_my_type = l_record.result_my_type;
--logic continues here
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER
COST 100;

Answer 4

In your f2() function, you could do the select into a record variable and then extract what you need from it, e.g.:
CREATE OR REPLACE FUNCTION f2(p_text text )
RETURNS record AS
$BODY$
DECLARE
record_var record;
BEGIN
--this statement was failing
SELECT * FROM f1(p_text) INTO record_var;
SELECT l_my_type.result_my_type.d_int1; -- this should work
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER
COST 100;