Add support for BigInt

[bitbytebit1]

Describe the feature

Currently if a BigInt needs to be sent to the client an error will be thrown.

[nuxt] [request error] [unhandled] [500] Do not know how to serialize a BigInt                                                                     1:31:58 PM
  at JSON.stringify (<anonymous>)  
  at Object.handler (./node_modules/h3/dist/index.mjs:1304:18)  
  at processTicksAndRejections (node:internal/process/task_queues:96:5)  
  at async toNodeHandle (./node_modules/h3/dist/index.mjs:1359:7)  
  at async ufetch (./node_modules/unenv/runtime/fetch/index.mjs:9:17)  
  at async $fetchRaw2 (./node_modules/ofetch/dist/shared/ofetch.d438bb6f.mjs:206:26)  
  at async $fetch2 (./node_modules/ofetch/dist/shared/ofetch.d438bb6f.mjs:239:15)  

Would love to see support for this!

One possible solution would be to use the reviver function. However I understand this would add complexity to both the sever and client. Wondering what the teams thoughts are regarding this functionality?

https://stackoverflow.com/questions/62539236/how-to-parse-a-json-data-type-bigint-in-typescript

Additional information

• Would you be willing to help implement this feature?

[pi0]

Thanks for issue. It will be supported in next version.

[bitbytebit1]

Amazing! One step closer to the Nuxter role!

[chenneil69]

@pi0 Hello, thought this might help providing some info to your work. I am using h3@1.12.0 and it seems to still have the same issue..

 ERROR  [nuxt] [request error] [unhandled] [500] Do not know how to serialize a BigInt
  at JSON.stringify (<anonymous>)  
  at handleHandlerResponse (./node_modules/.pnpm/h3@1.12.0/node_modules/h3/dist/index.mjs:2087:29)  
  at ./node_modules/.pnpm/h3@1.12.0/node_modules/h3/dist/index.mjs:1983:15  
  at async Object.callAsync (./node_modules/.pnpm/unctx@2.3.1/node_modules/unctx/dist/index.mjs:72:16)  
  at async Server.toNodeHandle (./node_modules/.pnpm/h3@1.12.0/node_modules/h3/dist/index.mjs:2266:7)

Thank you for any tips

[rmarquet21]

The issue with serializing BigInt values within objects or arrays remains unresolved.

Here's an example of an error encountered with h3@1.11.1:

ERROR  [nuxt] [request error] [unhandled] [500] Do not know how to serialize a BigInt
  at JSON.stringify (<anonymous>)  
  at handleHandlerResponse (./node_modules/h3/dist/index.mjs:2071:29)  
  at ./node_modules/h3/dist/index.mjs:1969:15  
  at async Object.callAsync (./node_modules/unctx/dist/index.mjs:72:16)  
  at async Server.toNodeHandle (./node_modules/h3/dist/index.mjs:2250:7)

It appears that the serialization of BigInt values, particularly when nested within objects or arrays, remains problematic.

Alternative solution for the moment that I propose:

type StringifyBigInt<T> = T extends bigint
  ? string
  : T extends (infer U)[]
    ? StringifyBigInt<U>[]
    : T extends object
      ? { [K in keyof T]: StringifyBigInt<T[K]> }
      : T;

export function stringifyBigInt<T>(body: T): StringifyBigInt<T> {
  if (typeof body !== 'object' || body === null) {
    return (typeof body === 'bigint' ? body.toString() : body) as StringifyBigInt<T>;
  }

  if (Array.isArray(body)) {
    return body.map(stringifyBigInt) as StringifyBigInt<T>;
  }

  return Object.fromEntries(
    Object.entries(body).map(([key, value]) => [key, stringifyBigInt(value)]),
  ) as StringifyBigInt<T>;
}

[Urriel]

type StringifyBigInt<T> = T extends bigint
  ? string
  : T extends (infer U)[]
    ? StringifyBigInt<U>[]
    : T extends object
      ? { [K in keyof T]: StringifyBigInt<T[K]> }
      : T;

export function stringifyBigInt<T>(body: T): StringifyBigInt<T> {
  if (typeof body !== 'object' || body === null) {
    return (typeof body === 'bigint' ? body.toString() : body) as StringifyBigInt<T>;
  }

  if (Array.isArray(body)) {
    return body.map(stringifyBigInt) as StringifyBigInt<T>;
  }

  return Object.fromEntries(
    Object.entries(body).map(([key, value]) => [key, stringifyBigInt(value)]),
  ) as StringifyBigInt<T>;
}

Your solution is not supporting Dates, here my updated version.
Thx for the previous code, I used it to create a nitro plugin for my nuxt app.

type StringifyBigInt<T> = T extends bigint
  ? string
  : T extends Date
    ? Date
    : T extends (infer U)[]
      ? StringifyBigInt<U>[]
      : T extends object
        ? { [K in keyof T]: StringifyBigInt<T[K]> }
        : T;

export function stringifyBigInt<T>(body: T): StringifyBigInt<T> {
  if (typeof body === 'bigint') {
    return body.toString() as StringifyBigInt<T>;
  }

  if (body instanceof Date || typeof body !== 'object' || body === null) {
    return body as StringifyBigInt<T>;
  }

  if (Array.isArray(body)) {
    return body.map(stringifyBigInt) as StringifyBigInt<T>;
  }

  return Object.fromEntries(
    Object.entries(body).map(([key, value]) => [key, stringifyBigInt(value)])
  ) as StringifyBigInt<T>;
}

[victorpagan]

@Urriel how exactly was this added as a Nitro plugin? I'm running into this problem but it seems I have to switch between how the BigInt is serialized due to how it's handled in another SDK. I'm wondering if your solution could resolve this for my particular instance.

[pi0]

This issue was fixed to allow directly returning a BigInt value.

Please refer to #995 (comment) for a follow-up conversation about returning objects with non-serializable values like BigInts.