Postgresql from url_query to json function

parse_url_query-functions.sql

CREATE OR REPLACE FUNCTION urldecode(p varchar) RETURNS varchar AS $$
SELECT convert_from( CAST(E'\\x' || string_agg( CASE WHEN length(r.m[1]) = 1 THEN encode(convert_to(r.m[1], 'SQL_ASCII'), 'hex') ELSE substring(r.m[1] from 2 for 2) END, '') AS bytea), 'UTF8')
FROM regexp_matches(replace($1, '+', ' '), '%[0-9a-f][0-9a-f]|.', 'gi') AS r(m);
$$ LANGUAGE SQL STRICT;

CREATE OR REPLACE FUNCTION parse_url_query(p varchar) RETURNS json AS $$
with kv as (
select urldecode(kv[1]) k, urldecode(kv[2]) v from (select string_to_array(i, '=') kv from unnest(string_to_array(TRIM(BOTH '&' FROM $1), '&')) as s(i))
)
select json_object(array(select k from kv), array(select v from kv));
$$ LANGUAGE SQL STRICT;