Postgres 12

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CREATE TABLE test (jsonb_value JSONB CHECK (jsonb_value::text ~ '^{"en": "[^"]+", "ru": "[^"]+"}$'));
insert into test values 
('{"en": "value", "ru": "значение"}');
1 rows affected

insert into test values 
('{"ru": "значение", "en": "value"}');
1 rows affected

insert into test values 
('{"en": 6, "ru": "значение"}');
ERROR:  new row for relation "test" violates check constraint "test_jsonb_value_check"
DETAIL:  Failing row contains ({"en": 6, "ru": "значение"}).


insert into test values 
('{"en": "", "ru": "значение"}');
ERROR:  new row for relation "test" violates check constraint "test_jsonb_value_check"
DETAIL:  Failing row contains ({"en": "", "ru": "значение"}).


insert into test values 
('{"en": "value", "ru": "значение", "fr": "de valuje"}');
ERROR:  new row for relation "test" violates check constraint "test_jsonb_value_check"
DETAIL:  Failing row contains ({"en": "value", "fr": "de valuje", "ru": "значение"}).