Simple word replacement in output from SQL - sql

Question

I'm running PostgreSQL 9.4.
Is there a replace string function which can take an array of words, or other similar function?
Ex.
SELECT REPLACE(my_column, ['blue', 'red'], ['ColorBlue', 'ColorRed']);
So blue becomes ColorBlue, and red becomes ColorRed?
It's not only such simple replacements, but for the example I'm using this.

Answer 1

One way is create it:
create or replace function rep_arr(str text, src text[], rep text[])
returns text as $$
begin
for i in 1..array_length(src, 1) loop
str := replace(str, src[i], rep[i]);
end loop;
return str;
end; $$ language plpgsql
Call:
select rep_arr('bla bla blue bla red bla', '{blue,red}' , '{ColorBlue,ColorRed}');

Answer 2

I agree with #OtoShavadze that you can write your own function.
Here is my solution:
I use generate_subscripts(array anyarray, dim int) function as suggested in Searching in Arrays documentation.
CREATE OR REPLACE FUNCTION translate(string text, from_array text[], to_array text[])
RETURNS text AS
$BODY$
DECLARE
output text;
BEGIN
SELECT INTO output
to_array[idx]
FROM
generate_subscripts(from_array, 1) AS idx
WHERE
from_array[idx] = string; -- here you can change the search condition
IF FOUND THEN
RETURN output;
ELSE
RETURN string;
END IF;
END;
$BODY$
LANGUAGE plpgsql VOLATILE;
It finds and replaces whole words but you can change it (line marked in the code) to find only a substring, match case-insensitive, etc...
You should also add parameter checking: arrays should not be null, multidimensional nor differ in size:
IF from_array IS NULL OR to_array IS NULL THEN
RAISE EXCEPTION 'NULL parameters';
END IF;
IF array_ndims(from_array) != 1 OR array_ndims(to_array) != 1 THEN
RAISE EXCEPTION 'Multidimensional parameters';
END IF;
IF array_length(from_array, 1) != array_length(to_array, 1) THEN
RAISE EXCEPTION 'Parameters size differ';
END IF;
SELECT translate('red', ARRAY['blue', 'red'], ARRAY['ColorBlue', 'ColorRed']);
returns
ColorRed