Postgres 14

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CREATE TABLE public.test_case_1 (
	test_case_1_id int8 NOT NULL GENERATED BY DEFAULT AS IDENTITY,
	column_var varchar NULL,
	column_int int4 NULL,
	column_bool bool NULL,
	lastupdatedon timestamptz NOT NULL DEFAULT now()
);

CREATE TABLE


INSERT INTO public.test_case_1
(column_var, column_int, column_bool)
VALUES('User A', 1, true),('User B', 1, true);

INSERT 0 2


CREATE TABLE public.test_case_1_meta (
	lang_id int4 not null,
	column_var varchar NULL,
	column_int varchar NULL,
	column_bool varchar NULL
);

CREATE TABLE


INSERT INTO public.test_case_1_meta
(lang_id, column_var, column_int, column_bool)
VALUES(2, 'columna var', 'columna int', 'columna bool');

INSERT 0 1


CREATE OR REPLACE FUNCTION translate_column(_tbl regclass, _column text, _language_id int, OUT translated_column TEXT)
  RETURNS text
  LANGUAGE plpgsql
AS $function$
BEGIN 
	
	EXECUTE format('SELECT QUOTE_IDENT(%s)
					FROM   %s 
					where lang_id = %s
					;', _column,_tbl,_language_id)
   INTO translated_column;
END
$function$
;

CREATE FUNCTION


CREATE OR REPLACE FUNCTION f_get_table_with_alias(_tbl regclass,_language_id int,_arr text[])
  RETURNS TABLE(json_agg text)
  LANGUAGE plpgsql AS
$func$
DECLARE
   m text[];  
   alias_text  text = '';
   meta_tbl text = _tbl || '_meta' ;
BEGIN
   FOREACH m SLICE 1 IN ARRAY _arr
   LOOP
	   
	  select alias_text || ' ' || m[1] || ' AS ' || translated_column || ',' from public.translate_column(meta_tbl,m[1], _language_id) into alias_text;

   END LOOP;

   select left(alias_text,-1) into alias_text;  
   RAISE NOTICE '%', alias_text;
  
   RETURN QUERY EXECUTE 'SELECT json_agg(t)::text FROM (
			select ' || alias_text || '
			from public.test_case_1 order by test_case_1_id)
			t';
END
$func$;

CREATE FUNCTION


SELECT * FROM f_get_table_with_alias('public.test_case_1',2,'{{column_var},{column_int}}');


json_agg


[{"columna var":"User A","columna int":1}, 
 {"columna var":"User B","columna int":1}]



SELECT 1