postgresql: converting CTE column to array - postgresql

Question

I am trying to convert one of the columns of CTE to array. I keep on getting "syntax error at or near" followed by "ret := array(".
My objective is that the table I am returning from a_function() in example below is stored as a variable to be referred later in function. But I could not find a syntax to do so. So, instead of using CTE, if I can use something else, that would work just as nicely.
Note: I am trying this in pgAdmin III.
create or replace function a_function()
--returns int[][] as
returns table(column1 int, column2 int) as
$body$
begin
return query
select 1,2;
end;
$body$
language 'plpgsql'
;
--select * from a_function();
create or replace function test_a_function()
returns void as
$body$
declare ret int[];
begin
with ret_cte(column1, column2) as (
select * from a_function()
)
ret := array(
select column1 from ret_cte
)
;
--raise notice '%', array_to_string(ret, ',');
end;
$body$
language 'plpgsql'
;
--select test_a_function();

Answer 1

I am trying to convert one of the columns of CTE to array. I keep on getting "syntax error at or near" followed by "ret := array("
You could use:
ret :=array(with ret_cte(column1, column2) as (
select * from a_function()
)
select column1 from ret_cte
);
Rextester Demo

Answer 2

Arrays can be built and returned using the array_agg() function. For example, your second function could be written using a SQL language function that returns the array as follows:
create or replace function test_a_function()
returns int[] as
$body$
select array_agg(column1) from a_function();
$body$
language 'sql';
Alternatively, you can assign the array to a variable like this:
create or replace function test_a_function()
returns void as
$body$
declare
ret int[];
begin
select array_agg(column1)
into ret
from a_function();
raise info '%', ret;
end;
$body$
language 'plpgsql';