fix: support string to number type in JSONB_POPULATE_RECORD

[zwang28]

I hereby agree to the terms of the RisingWave Labs, Inc. Contributor License Agreement.

What's changed and what's your intention?

close #19918

Checklist

• I have written necessary rustdoc comments.
• I have added necessary unit tests and integration tests.
• I have added test labels as necessary.
• I have added fuzzing tests or opened an issue to track them.
• My PR contains breaking changes.
• My PR changes performance-critical code, so I will run (micro) benchmarks and present the results.
• My PR contains critical fixes that are necessary to be merged into the latest release.

Documentation

• My PR needs documentation updates.

Release note

[zwang28]

Is decimal excluded here by design?

@xiangjinwu

[xiangjinwu]

Keep as_number at its current behavior and let its caller (JSONB_POPULATE_RECORD) to do more work.

Besides JSONB_POPULATE_RECORD, or actually before JSONB_POPULATE_RECORD is supported, this as_number is intended to support CAST. In PostgreSQL:

test=# select ('{"f1":4}'::jsonb -> 'f1')::int;
 int4 
------
    4
(1 row)

test=# select ('{"f1":"4"}'::jsonb -> 'f1')::int;
ERROR:  cannot cast jsonb string to type integer

That is, a JSON string shall NOT be CASTed into integer. But it can be POPULATEed into integer:

test=# select jsonb_populate_record(row(null::int), '{"f1":4}');
 jsonb_populate_record 
-----------------------
 (4)
(1 row)

test=# select jsonb_populate_record(row(null::int), '{"f1":"4"}');
 jsonb_populate_record 
-----------------------
 (4)
(1 row)

This is the PostgreSQL doc on JSONB_POPULATE_RECORD:
https://www.postgresql.org/docs/17/functions-json.html#id-1.5.8.22.8.13.2.2.9.1.2.1

To convert a JSON value to the SQL type of an output column, the following rules are applied in sequence:

• A JSON null value is converted to an SQL null in all cases.
• If the output column is of type json or jsonb, the JSON value is just reproduced exactly.
• If the output column is a composite (row) type, and the JSON value is a JSON object, the fields of the object are converted to columns of the output row type by recursive application of these rules.
• Likewise, if the output column is an array type and the JSON value is a JSON array, the elements of the JSON array are converted to elements of the output array by recursive application of these rules.
• Otherwise, if the JSON value is a string, the contents of the string are fed to the input conversion function for the column's data type.
• Otherwise, the ordinary text representation of the JSON value is fed to the input conversion function for the column's data type.

That is, only null/jsonb/object/array get special treatment. Other cases (bool/number) are always force_str (function defined below) first and then from_text (defined here as the input conversion function).

[xiangjinwu]

Is decimal excluded here by design?

@xiangjinwu

No. According to the PostgreSQL doc I just shared above, all data types having an input conversion function can be supported.