Using JSONB_ARRAY_ELEMENTS with WHERE ... IN condition

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.

Is there a specific reasons why you would use a jsonb array? Why not use an int[] array? — Patrick
– Patrick, Commented Feb 27, 2016 at 19:53
Yes, I'd like to use JSON, because that is how my mobile app talks to the PHP + PostrgreSQL backend. I'm sure my problem is solvable with JSON, I am just missing smth. minor. — Alexander Farber
– Alexander Farber, Commented Feb 27, 2016 at 20:11

Dzmitry Savinkou · Accepted Answer · 2016-02-27 20:30:54Z

7

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...

edited Feb 27, 2016 at 20:30

answered Feb 27, 2016 at 20:18

Dzmitry Savinkou

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