ERROR: operator does not exist: jsonb[] -> integer - arrays

Question

select id,rules from links where id=2;
id | rules
----+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2 | {"{\"id\": \"61979e81-823b-419b-a577-e2acb34a2f40\", \"url\": \"https://www.wikijob.co.uk/about-us\", \"what\": \"country\", \"matches\": \"GB\", \"percentage\": null}"}
I'm trying to get the elements of the jsonb using the operators here https://www.postgresql.org/docs/9.6/functions-json.html
Whether I use 'url', or an integer as below, I get a similar result.
select id,rules->1 from links where id=2;
ERROR: operator does not exist: jsonb[] -> integer
LINE 1: select id,rules->1 from links where id=2;
^
HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.
What am I doing wrong?
PS Postgres version 9.6.12.

Answer 1

The column is an array, you can access the first element using index:
select id, rules[1]
from links
where id = 2
Be sure to check also this answer.
Use jsonb_each() in a lateral join to see all rules in separate rows:
select id, key, value
from links
cross join jsonb_each(rules[1]) as rule(key, value)
where id = 2
You can get a single rule in this way:
select id, value as url
from links
cross join jsonb_each(rules[1]) as rule(key, value)
where id = 2 and key = 'url'
Use unnest() to find an url in all elements of the array, e.g.:
select id, unnest(rules)->'url' as url
from links
where id = 2;