How to formulate an array literal of a composite type containing arrays?

Question

I have a composite type like

CREATE TYPE example AS (id integer, some_stuff integer[]);

Thought I can use an array of this type as an argument of a function. The only problem is I couldn't find a way to build an array literal for that... If I try obtain it from PostgreSQL:

WITH elements AS (
    SELECT (12, '{1,2}')::example AS e UNION 
    SELECT (3, '{3,1}')::example 
)
SELECT array_agg(e) FROM elements;

I get the following:

{"(3,\"{3,1}\")","(12,\"{1,2}\")"}

But look:

SELECT E'{"(3,\"{3,1}\")","(12,\"{1,2}\")"}'::example[];

ERROR:  malformed array literal: "{"(3,"{3,1}")","(12,"{1,2}")"}"
LINE 1: select E'{"(3,\"{3,1}\")","(12,\"{1,2}\")"}'::example[]

Is there a way to do this?

Answer 1

Try using ARRAY and ROW constructors:

Select array[row(3, array[3,1]), row(12, array[1,2])]::example[];
               array
------------------------------------
 {"(3,\"{3,1}\")","(12,\"{1,2}\")"}
(1 row)

If you want solution without using constructors, then use following example:

Select E'{"(3,\\"{3,1}\\")","(12,\\"{1,2}\\")"}'::example[];
              example
------------------------------------
 {"(3,\"{3,1}\")","(12,\"{1,2}\")"}
(1 row)

As you see main issue here is that you need to write \\", because this effectively means \" (using "escape" string syntax) that you saw as output of your first select.