'{"a":1, "b":2, "c":3}'::jsonb ?& array['a', 'b'] checks if right hand side, an array of text, is contained by the top-level keys of the left hand side.
How can I check the opposite? That is, whether the keys of the json string are from a known set of texts.
You can get the keys of your object with json(b)_object_keys and collect them into an array. Then use the array contains operator:
array(SELECT jsonb_object_keys('{"a":1, "b":2, "c":3}'::jsonb)) <@ array['a', 'b']
Alternatively, you could use a subquery on the keys and conjugate tests against the array (equivalent to the NOT EXISTS check by @GMB):
SELECT bool_and(k = ANY(array['a', 'b'])) FROM jsonb_object_keys(object) as k
You can use jsonb_object_keys() and ANY like so:
select 1
from jsonb_object_keys(t.js) o(x)
where not x = ANY(ar)
Here is how to use this in a query:
with t as (
select '{"a":1, "b":2, "c":3}'::jsonb js, array['a', 'b', 'c'] ar
union all select '{"a":1, "b":2, "z":3}'::jsonb js, array['a', 'b'] ar
)
select
js,
ar,
not exists(
select 1
from jsonb_object_keys(t.js) o(x)
where not x = ANY(ar)
) res
from t
Yields:
js | ar | res
:----------------------- | :------ | :-----
{"a": 1, "b": 2, "c": 3} | {a,b,c} | true
{"a": 1, "b": 2, "z": 3} | {a,b} | false
