Roundtripping bigint and number

[LeviticusMB]

I'm using the parser as a JSON alternative, that is, i want to parse/serialize objects, arrays and primitives.

I can call YAML.parseAllDocuments(..., { intAsBigInt: true }) go get a document collection with bigint nodes, also preserved when calling toJS({ mapAsMap: false, ...}). bigint is also serialized OK. All good here.

However, I also need to ensure that a number is never serialized as an integer but always a float, or else the number will turn into a bigint after serdes.

How would I do that? (For JSON, I have a replacer is basically just returning JSON.rawJSON(`${serialized}.0`) if serialized is all digits.)

[LeviticusMB]

OK, I managed to hack it but it's not pretty:

const stringify = (value: unknown) => {
    const doc = new YAML.Document(value);

    YAML.visit(doc, (key, node) => {
        if (key === 'value' && node instanceof YAML.Scalar && typeof node.value === 'number' && /^[-+0-9]+$/.test(JSON.stringify(node.value))) {
            node.minFractionDigits ??= 1;
        }
    });

    return doc.toString();
};

The regexp test is there to prevent 1e32 from becoming 1e32.0, which I think is a bug?

Is there a better way?

[eemeli]

Using visit() for this seems entirely valid; wanting to serialize all Number values with fraction digits does seem like a rare enough use case that I doubt it makes sense to add a separate option for it. I'd do it like this:

YAML.visit(doc, {
  Scalar(key, node) {
    if (Number.isInteger(node.value)) node.minFractionDigits ||= 1;
  }
});

The regexp test is there to prevent 1e32 from becoming 1e32.0, which I think is a bug?

Yeah, that's a bug that needs to be fixed.

[eemeli]

Fixed here: b2a5a6c

[eemeli]

yaml-types has !bigint, would that work for you?

[LeviticusMB]

Hm, not really. This is among other things for a generic web service and I'd rather not impose any special requirements onto the clients.

smol-toml has integersAsBigInt for parsing and numbersAsFloat for serializing, which was exactly what I wanted. Maybe consider a similar flag in the future?