Laurenz Albe schrieb am 17.10.2019 um 13:25: >> I don't understand why the following two JSON Path expressions aren't doing the same thing in Postgres 12: >> >> jsonb_path_exists(data, '$.k1.list.type() ? (@ == "array")'), -- returns true as expected >> jsonb_path_exists(data, '$.k1.list ? (@.type() == "array")') -- returns false - not expected >> >> Apparently "@.type()" returns something different then "$.k1.list.type()" >> > This seems to be a consequence of "lax" mode: > > "Besides, comparison operators automatically unwrap their operands in the lax mode, > so you can compare SQL/JSON arrays out-of-the-box. An array of size 1 is considered > equal to its sole element. Automatic unwrapping is not performed only when: > > - The path expression contains type() or size() methods that return the type and > the number of elements in the array, respectively. > > (from https://www.postgresql.org/docs/12/functions-json.html) > > with sample (data) as ( > values > ('{"k1": {"list":[1,2,3]}}'::jsonb) > ) > select data, > jsonb_path_exists(data, '$.k1.list ? (@.type() == "number")'), -- lax mode unwraps the array > jsonb_path_exists(data, 'strict $.k1.list ? (@.type() == "array")') -- strict mode doesn't > from sample; Ah, thanks. I did not see that part.
