gustavodemorais commented on code in PR #28688:
URL: https://github.com/apache/flink/pull/28688#discussion_r3615257667
##########
flink-table/flink-table-planner/src/test/java/org/apache/flink/table/planner/functions/JsonFunctionsITCase.java:
##########
@@ -201,6 +201,13 @@ private static TestSetSpec jsonLengthSpec() {
.testSqlResult("JSON_LENGTH(f0, '$.metadata.tags[*]')", null,
INT().nullable())
.testSqlResult("JSON_LENGTH(f0, '$.metadata.tags')", 3,
INT().nullable())
+ // JSON_EXISTS sees a multi-match wildcard as present while
JSON_LENGTH returns NULL
+ .testSqlResult(
+ "JSON_EXISTS(f0, 'lax $.metadata.tags[*]') "
+ + "AND JSON_LENGTH(f0, '$.metadata.tags[*]')
IS NULL",
Review Comment:
Simplify test as here
https://github.com/apache/flink/pull/28688/changes/eb2c40daa07a0b998dad9b098b04758aefb99826#r3614478354
##########
docs/data/sql_functions.yml:
##########
@@ -1264,25 +1264,9 @@ json:
-- JSON_EXISTS separates an absent path from a present one
SELECT JSON_EXISTS(json_doc, '$.items[*]'), JSON_LENGTH(json_doc,
'$.items[*]');
- -- To count multiple wildcard matches, wrap them into an array first
- SELECT JSON_LENGTH(JSON_QUERY(json_doc, '$.items[*]' WITH ARRAY
WRAPPER));
-
-
- eg.
- consider this JSON_LENGTH query JSON_LENGTH('{"1": "hello", "2": "BAD
SYNTAX ->"', '$.2'),
- this string will return NULL, however as a user, to understand why we
must use the parameter,
- "IS JSON" and function "JSON_EXISTS()".
-
- In order to understand why JSON_LENGTH gave a NULL output you can look
at the following example:
-
- -- '{"1": "hello", "2": "BAD SYNTAX ->"' IS JSON
- This will return FALSE if we have a malformed JSON input.
-
- -- JSON_EXISTS('{"1": "hello", "2": "BAD SYNTAX ->"', '$.2')
- This will return FALSE if the path given is an invalid path in our
given JSON string or
- invalid JSON, so you must do "IS JSON" first to get a definative
answer. However if this
- returns TRUE and the JSON input is validated already, it means that
the path describes
- two or more paths (ie. using the wildcard operator), which
JSON_LENGTH doesnt support.
+ -- JSON_EXISTS separates a multi-match path from a present one
+ (returns True if multimatch is present given f0 is a valid json
string otherwise returns False)
+ SELECT JSON_EXISTS(f0, 'lax $.metadata.tags[*]') AND JSON_LENGTH(f0,
'$.metadata.tags[*]') IS NULL;
Review Comment:
Why do you think this is worth being in the docs? I think we can just remove
it. As I mentioned, I think we're giving the multi-match wildcard case more
effort than it deserves. It's a very rare case and users should write the
wildcard in a way that it matches paths individually, so I don't think we need
to give specific instructions to this on the docs
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