Using JSONB_ARRAY_ELEMENTS with WHERE ... IN condition - postgresql

Question

Online poker players can optionally purchase access to playroom 1 or playroom 2.
And they can be temporarily banned for cheating.
CREATE TABLE users (
uid SERIAL PRIMARY KEY,
paid1_until timestamptz NULL, -- may play in room 1
paid2_until timestamptz NULL, -- may play in room 2
banned_until timestamptz NULL, -- punished for cheating etc.
banned_reason varchar(255) NULL
);
Here the above table is filled with 4 test records:
INSERT INTO users (paid1_until, paid2_until, banned_until, banned_reason)
VALUES (NULL, NULL, NULL, NULL),
(current_timestamp + interval '1 month', NULL, NULL, NULL),
(current_timestamp + interval '2 month', current_timestamp + interval '4 month', NULL, NULL),
(NULL, current_timestamp + interval '8 month', NULL, NULL);
All 4 records belong to the same person - who has authenticated herself via different social networks (for example through Facebook, Twitter, Apple Game Center, etc.)
I am trying to create a stored function, which would take a list of numeric user ids (as a JSON array) and merge records belonging to same person into a single record - without losing her payments or punishments:
CREATE OR REPLACE FUNCTION merge_users(
IN in_users jsonb,
OUT out_uid integer)
RETURNS integer AS
$func$
DECLARE
new_paid1 timestamptz;
new_paid2 timestamptz;
new_banned timestamptz;
new_reason varchar(255);
BEGIN
SELECT min(uid),
current_timestamp + sum(paid1_until - current_timestamp),
current_timestamp + sum(paid2_until - current_timestamp),
max(banned_until)
INTO
out_uid, new_paid1, new_paid2, new_banned
FROM users
WHERE uid IN (SELECT JSONB_ARRAY_ELEMENTS(in_users));
IF out_uid IS NOT NULL THEN
SELECT banned_reason
INTO new_reason
FROM users
WHERE new_banned IS NOT NULL
AND banned_until = new_banned
LIMIT 1;
DELETE FROM users
WHERE uid IN (SELECT JSONB_ARRAY_ELEMENTS(in_users))
AND uid <> out_uid;
UPDATE users
SET paid1_until = new_paid1,
paid2_until = new_paid2,
banned_until = new_banned,
banned_reason = new_reason
WHERE uid = out_uid;
END IF;
END
$func$ LANGUAGE plpgsql;
Unfortunately, its usage results in the following error:
# TABLE users;
uid | paid1_until | paid2_until | banned_until | banned_reason
-----+-------------------------------+-------------------------------+--------------+---------------
1 | | | |
2 | 2016-03-27 19:47:55.876272+02 | | |
3 | 2016-04-27 19:47:55.876272+02 | 2016-06-27 19:47:55.876272+02 | |
4 | | 2016-10-27 19:47:55.876272+02 | |
(4 rows)
# select merge_users('[1,2,3,4]'::jsonb);
ERROR: operator does not exist: integer = jsonb
LINE 6: WHERE uid IN (SELECT JSONB_ARRAY_ELEMENTS(in_users))
^
HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.
QUERY: SELECT min(uid),
current_timestamp + sum(paid1_until - current_timestamp),
current_timestamp + sum(paid2_until - current_timestamp),
max(banned_until)
FROM users
WHERE uid IN (SELECT JSONB_ARRAY_ELEMENTS(in_users))
CONTEXT: PL/pgSQL function merge_users(jsonb) line 8 at SQL statement
Please help me to solve the problem.
Here is a gist with SQL code for your convenience.

Answer 1

Result of jsonb_array_elements() is a set of jsonb elements, therefore you need add explicit cast of uid to jsonb with to_jsonb() function, IN will be replaced with <# operator:
WITH t(val) AS ( VALUES
('[1,2,3,4]'::JSONB)
)
SELECT TRUE
FROM t,jsonb_array_elements(t.val) element
WHERE to_jsonb(1) <# element;
For your case, snippet should be adjusted to something like:
...SELECT ...,JSONB_ARRAY_ELEMENTS(in_users) user_ids
WHERE to_jsonb(uid) <# user_ids...