json ( expression [ FORMAT JSON [ ENCODING UTF8 ]] [ { WITH | WITHOUT } UNIQUE [ KEYS ]] ) → jsonConverts a given expression specified as text or bytea string (in UTF8 encoding) into a JSON value. If expression is NULL, an SQL null value is returned. If WITH UNIQUE is specified, the expression must not contain any duplicate object keys.json('{"a":123, "b":[true,"foo"], "a":"bar"}') → {"a":123, "b":[true,"foo"], "a":"bar"}