ABI coding: representing bytes as Uint8Array

[timbrinded]

Is there an existing issue for this?

• I have searched the existing issues

Package Version

1.4.1

Current Behavior

The encodeFunctionData() fn can't seem to turn uint arrays into bytes when using as an args parameter.

Workaround is to use fromBytes() to first convert to a hex string, but this is non-ideal.

Expected Behavior

encodeFunctionData() should be able to handle native bytes input

Steps To Reproduce

import { encodeFunctionData } from 'viem';

const fragment = [
  {
    inputs: [{ internalType: 'bytes', name: 'innerCall', type: 'bytes' }],
    name: 'testFn',
    outputs: [],
    stateMutability: 'nonpayable',
    type: 'function',
  },
];

const notWorking = encodeFunctionData({
  abi: fragment,
  functionName: 'testFn',
  args: [new Uint8Array([0x01])],
});

console.log(notWorking + ' ❌');

Link to Minimal Reproducible Example (StackBlitz, CodeSandbox, GitHub repo etc.)

https://stackblitz.com/edit/viem-getting-started-dmhpsz?file=main.ts

Anything else?

Run the above with pnpm example

❯ pnpm example

> [email protected] example /home/projects/viem-getting-started-dmhpsz
> tsx main.ts

1 ✅
0x86fddd71000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000010100000000000000000000000000000000000000000000000000000000000000 ✅
Error: hex_.replace is not a function
    at async ESMLoader.import (https://viemgettingstarteddmhpsz-q2xc.w-credentialless.staticblitz.com/blitz.bec01ace.js:35:1347715)
    at async i.loadESM (https://viemgettingstarteddmhpsz-q2xc.w-credentialless.staticblitz.com/blitz.bec01ace.js:35:352602)
    at async handleMainPromise (https://viemgettingstarteddmhpsz-q2xc.w-credentialless.staticblitz.com/blitz.bec01ace.js:35:1051734)
 ELIFECYCLE  Command failed with exit code 1.

[jxom]

Going to convert this one to a discussion as it’s not really a bug. viem represents bytes(N) as Hex in coding functions (with the escape hatch of fromBytes as you mentioned) as the performance cost of converting typed arrays (Uint8Array) to Hex internally is quite costly, and we don’t really want to encourage this.

If there is larger demand for this, maybe we can find an API to make it a bit easier.