How to cast json array to text array?

Question

This workaround not works

CREATE FUNCTION json_array_castext(json) RETURNS text[] AS $f$
  SELECT array_agg(x::text) FROM json_array_elements($1) t(x);
$f$ L         


        

Answer 1

In my case it helped to have the result reflect 3 states, null, empty text array and non-empty text array depending on the input. Hopefully this will be useful to someone.

CREATE OR REPLACE FUNCTION json_array_text_array(JSON)
  RETURNS TEXT [] AS $$
DECLARE
  result TEXT [];
BEGIN
  IF $1 ISNULL
  THEN
    result := NULL;
  ELSEIF json_array_length($1) = 0
    THEN
      result := ARRAY [] :: TEXT [];
  ELSE
    SELECT array_agg(x) FROM json_array_elements_text($1) t(x) INTO result;
  END IF;
  RETURN result;
END;
$$
LANGUAGE plpgsql
IMMUTABLE
STRICT;