Re: Transform for pl/perl

Tom Lane <tgl@sss.pgh.pa.us> writes:

> ilmari@ilmari.org (Dagfinn Ilmari =?utf-8?Q?Manns=C3=A5ker?=) writes:
>> While playing around some more with the extension, I discoverered a few
>> more issues:
>> ...
>> 4) SV_to_JsonbValue() throws an error for infinite NVs, but not NaNs
>
> The others sound like bugs, but that one's intentional, since type
> numeric does have a concept of NaN.  If you're arguing that we should
> disallow that value in the context of jsonb, maybe so, but it'd likely
> take changes in quite a few more places than here.

The numeric type that's used internally to represent numbers in jsonb
might have the concept of NaN, but JSON itself does not:

    Numeric values that cannot be represented in the grammar below (such
    as Infinity and NaN) are not permitted.

      - https://tools.ietf.org/html/rfc7159#section-6

And it cannot be cast to json:

    =# create or replace function jsonbnan() returns jsonb immutable language plperlu transform for type jsonb as '0+"NaN"';
    CREATE FUNCTION
    =# select jsonbnan();
    ┌──────────┐
    │ jsonbnan │
    ├──────────┤
    │ NaN      │
    └──────────┘

    =# select jsonb_typeof(jsonbnan());
    ┌──────────────┐
    │ jsonb_typeof │
    ├──────────────┤
    │ number       │
    └──────────────┘

    =# select jsonbnan()::json;
    ERROR:  invalid input syntax for type json
    DETAIL:  Token "NaN" is invalid.
    CONTEXT:  JSON data, line 1: NaN

- ilmari
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