option to keep padding for quantities

[passabilities]

Allows to optionally keep the leading 0s when converting a value to a Quantity.

[ricmoo]

That’s what hexlify does; it doesn’t remove leading 0’s. A “quantity” type forbids leading 0’s, which is the purpose of that function, but if you use hexlify it will retain the zeros.

What do you need this functionality for?

[passabilities]

for instance when a number needs to be represented by all 32 bytes but there are leading 0s in the hex number take this example:

> num = BigInt('0x044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d')
1937035142596246788172577232054709726386880441279550832067530347910661804397n
> ethers.hexlify(num)
Uncaught:
TypeError: invalid BytesLike value (argument="value", value=1937035142596246788172577232054709726386880441279550832067530347910661804397, code=INVALID_ARGUMENT, version=6.8.0)
    at makeError (./node_modules/ethers/lib.commonjs/utils/errors.js:122:21)
    at assert (./node_modules/ethers/lib.commonjs/utils/errors.js:149:15)
    at assertArgument (./node_modules/ethers/lib.commonjs/utils/errors.js:161:5)
    at _getBytes (./node_modules/ethers/lib.commonjs/utils/data.js:27:36)
    at getBytes (./node_modules/ethers/lib.commonjs/utils/data.js:37:12)
    at Object.hexlify (./node_modules/ethers/lib.commonjs/utils/data.js:84:19) {
  code: 'INVALID_ARGUMENT',
  argument: 'value',
  value: 1937035142596246788172577232054709726386880441279550832067530347910661804397n,
  shortMessage: 'invalid BytesLike value'
}
> ethers.toQuantity(num)
'0x44852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d'

• hexlify throws an error because its an odd number of bytes (leading 0)
• toQuantity strips the 0 making the number an odd number of bytes

I need all 32 bytes to be populated when converting an ENS token ID from a decimal number into a hex which represents the token's labelhash

this is not trivial to ensure I have the correct value but becomes annoying when you need to remember this 1 edge case and reproduce the following code to work:

    const q = ethers.toQuantity(opts.tokenId)
    const labelhash = ethers.zeroPadValue(q.length % 2 ? `0x0${q.substring(2)}` : q, 32)
    const url = 'https://api.thegraph.com/subgraphs/name/ensdomains/ens'
    const res: { registrations: [ { domain: { name: string } } | undefined ] } = await request(url, gql`
        query {
            registrations(
              where: { domain_: { labelhash: "${labelhash}" } }
            ) { domain { name } }
        }`,
    )

[passabilities]

iirc in v5 hexlify did not throw an error and did exactly want I wanted

[ricmoo]

In v5, hexlify accepted a numeric type; the equivalent in v6 is toBeArray, to be more explicit about how input types should be processed.

It also isn’t safe to use v5 hexlify to get a 32-byte value from a bigint; it might usually work out (because of how hashing works, often having non-zero values in high-order bits), but if for example the hex string were to begin with 0x000 the final string would be only 31 bytes wide.

For now, I think you would want zeroPadValue(toBeArray(value), 32) to ensure you get a 32 byte (64 nibble) hex string.

It may make sense for zeroPadValue to accept a BigInt or number as well, though.

[ricmoo]

You can also use abiCoder.encode([ "uint" ], [ value ]). Whatever best conveys the intention of the code, is best. :)