xdrjson: Rust: Render 64-bit integers as strings

[leighmcculloch]

What

Render 64-bit integers as strings in JSON.

Why

JS runtimes cannot correctly decode JSON numbers greater than 53-bits.

[leighmcculloch]

Given that so many tools support 64-bit integers in JSON I'm thinking maybe we should follow a pattern I've heard folks using, where the 64-bit integer is encoded into two fields, in a number in a field by it's native name, and in a string in a field by its native name suffixed with _str.

For example:

{
    "my_field": 1,
    "my_field_str": "1",
    // ...

The downside of this is that someone may still use the my_field in JS and unknowingly be interpreting the JSON data as a Number with lost precision.

[leighmcculloch]

If 64-bit integers become rendered as strings, and 128-bit and 256-bit integers also become rendered as strings (stellar/rs-stellar-xdr#430), should XDR-JSON render 32-bit integers as strings for consistency?

[Shaptic]

@leighmcculloch I would prefer using number of 32 bits - this aligns with other APIs and follows a "native support when possible" approach.

[kalepail]

I too am in favor of a "native support when possible" approach though I don't feel strongly about this. As long as whatever we use BigInt works with (which right now it doesn't as we use the JSON hi lo stuff) I'm good with

[leighmcculloch]

Discussion:

• [SEP-51] XDR-JSON stellar-protocol#1702 (comment)

[leighmcculloch]

Opened issue on serde_json about difficulty specifying 64-bit integers serialize when they are inside other types:

• Handle 64-bit types encoded as strings for cases not supported by field attributes serde-rs/json#1259