Join Postgresql jsonb object with an item from an array in values - sql

Question

I have two tables in my postgresql database which I want to join:
Table 1) platforms:
ID (INT) | data (JSONB)
------------+---------------------------------------------------------
1 | {"identity": "1", "platformName": "Teradata" }
2 | {"identity": "2", "platformName": "MSSQL" }
Table 2) users:
ID (INT) | data (JSONB)
------------+-----------+---------------
12 | { "role": "developer", "identity": "12", "accessRights": {"platforms": ["1"]} }
13 | { "role": "admin", "identity": "13", "accessRights": {"platforms": ["1", "2"]}" }
I need to get the list of platforms along with the list of users who has access to them. Something like this:
Platform ID | data (JSONB)
------------+-----------+---------------
1 | [{"role": "developer", "identity": "12"}]
2 | [{"role": "developer", "identity": "12"}, {"role": "admin", "identity": "13"}]
I thought maybe something like this can help:
SELECT p.id, u.id, u.role
FROM users u
INNER JOIN platforms p ON (u.data->>'accessRights'->'platforms')::text::int = p.id
GROUP BY p.id
But I can't make it work. So is there anyway to get the result I need?

Answer 1

A simple join is not enough because you need to aggregate information from the users.data JSON for each platform.
select p.id as platform_id, u.*
from platforms p
cross join lateral (
select jsonb_agg(u.data - 'accessRights') as data
from users u
where u.data -> 'accessRights' -> 'platforms' ? p.id::text
) as u
Note this only works because you stored the platform IDs in the array as strings, not as (JSON) integers, because the ? operator only works on strings.
Online example