How to get the values from an array?

[andreachello]

Hi, im trying to log out the first element of the array:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract Greeter {
    uint256[] public arr = [1, 2, 3];
}

by doing this

async function callFunction(vm: VM, contractAddress: Address, caller: Address) {
  const sigHash = new Interface(['function arr(uint256)']).getSighash('arr')

  // Encode the parameter
  const encodedParams = defaultAbiCoder.encode(['uint256'], [0])

  // Combine sigHash with encoded parameters
  const data = hexToBytes(sigHash + encodedParams.slice(2))

  const callResult = await vm.evm.runCall({
    to: contractAddress,
    caller: caller,
    origin: caller,
    data: hexToBytes(data),
    block,
  })

  if (callResult.execResult.exceptionError) {
    throw callResult.execResult.exceptionError
  }

  const results = AbiCoder.decode(['uint256'], callResult.execResult.returnValue)

  return parseInt(results[0])
}

but it gives me an error: EvmError { error: 'revert', errorType: 'EvmError' }
(everything else is correct I am using the examples from this repo)

[jochem-brouwer]

This works for me:

async function getGreeting(vm: VM, contractAddress: Address, caller: Address) {
  const sigHash = new Interface(['function arr(uint256)']).getFunction('arr')!.selector

  // Encode the parameter
  const encodedParams = new AbiCoder().encode(['uint256'], [0])

  // Combine sigHash with encoded parameters
  const data = hexToBytes(sigHash + encodedParams.slice(2))

  const greetResult = await vm.evm.runCall({
    to: contractAddress,
    caller,
    origin: caller, // The tx.origin is also the caller here
    data,
    block,
  })

  if (greetResult.execResult.exceptionError) {
    throw greetResult.execResult.exceptionError
  }

  const results = new AbiCoder().decode(['uint256'], greetResult.execResult.returnValue)

  return parseInt(results[0])
}

This uses an older (?) version of ethers maybe. I also noticed you are doing data: hexToBytes(data), but data is already a bytes type const data = hexToBytes(sigHash + encodedParams.slice(2)). Are you using TypeScript?

[andreachello]

I'm using this version of the repo since the latest hasn't yet been released on NPM

4c37ccc

and I am unable to get the call to work

[andreachello]

Here is a repo i made so you can recreate the error

https://github.com/andreachello/ejs

[jochem-brouwer]

The array in your repo is called arr2 in Greeter.sol, change it to arr, otherwise the sighash will not match.