Multiple functions to modify json objects in PostgreSQL

json_object_agg.sql

-- Aggregate function to aggregate key-value pairs to json object (opposite of json_each())
-- requires PostgreSQL 9.3+ (but < 9.4!)
-- requires function "json_object_set_key"

DROP AGGREGATE IF EXISTS "json_object_agg" (TEXT, anyelement);

CREATE AGGREGATE "json_object_agg" (TEXT, anyelement)
(
  STYPE     = json,
  SFUNC     = "json_object_set_key",
  INITCOND  = '{}'
);

json_object_delete_keys.sql

-- SQL function to delete key(s) from a json object
-- requires PostgreSQL 9.3+

CREATE OR REPLACE FUNCTION "json_object_delete_keys"(
  "json" json,
  VARIADIC "keys_to_delete" TEXT[]
)
  RETURNS json
  LANGUAGE sql
  IMMUTABLE
  STRICT
AS $function$
SELECT COALESCE(
  (SELECT ('{' || string_agg(to_json("key") || ':' || "value", ',') || '}')
     FROM json_each("json")
    WHERE "key" <> ALL ("keys_to_delete")),
  '{}'
)::json
$function$;

json_object_set_key.sql

-- SQL function to set a key to a specific value within a json object
-- requires PostgreSQL 9.3+

CREATE OR REPLACE FUNCTION "json_object_set_key"(
  "json"          json,
  "key_to_set"    TEXT,
  "value_to_set"  anyelement
)
  RETURNS json
  LANGUAGE sql
  IMMUTABLE
  STRICT
AS $function$
SELECT COALESCE(
  (SELECT ('{' || string_agg(to_json("key") || ':' || "value", ',') || '}')
     FROM (SELECT *
             FROM json_each("json")
            WHERE "key" <> "key_to_set"
            UNION ALL
           SELECT "key_to_set", to_json("value_to_set")) AS "fields"),
  '{}'
)::json
$function$;

json_object_set_keys.sql

-- SQL function to set keys to specific values within a json object
-- requires PostgreSQL 9.3+

CREATE OR REPLACE FUNCTION "json_object_set_keys"(
  "json"          json,
  "keys_to_set"   TEXT[],
  "values_to_set" anyarray
)
  RETURNS json
  LANGUAGE sql
  IMMUTABLE
  STRICT
AS $function$
SELECT COALESCE(
  (SELECT ('{' || string_agg(to_json("key") || ':' || "value", ',') || '}')
     FROM (SELECT *
             FROM json_each("json")
            WHERE "key" <> ALL ("keys_to_set")
            UNION ALL
           SELECT DISTINCT ON ("keys_to_set"["index"])
                  "keys_to_set"["index"],
                  CASE
                    WHEN "values_to_set"["index"] IS NULL THEN 'null'
                    ELSE to_json("values_to_set"["index"])
                  END
             FROM generate_subscripts("keys_to_set", 1) AS "keys"("index")
             JOIN generate_subscripts("values_to_set", 1) AS "values"("index")
            USING ("index")) AS "fields"),
  '{}'
)::json
$function$;

how to pass array of keys to json_object_delete_keys