How to get a ERC20 token's historic balance?

[logan272]

hi folks,

I'm not able to get the historical(a snapshot at a specific block) ERC20 token balances

function getERC20Balance({
  abi,
  erc20ContractAddress,
  accountAddress,
  blockTag,
}) {
  // the provider connected to a archive Ethereum node
  const provider = getProvider();
  const contract =  new ethers.Contract(
    address,
    abi,
    provider,
  );
  
  return contract.balanceOf(accountAddress, {blockTag});
}

// Expected to return the balance at `xxx` block, but it always returns the latest block balance
const balance = getERC20Balance({
  abi: ['function balanceOf(address) view returns (uint)'],
  erc20ContractAddress: 'xxx',
  accountAddress: 'xxx',
  blockTag: xxx
});

I tried the same by calling provide.call({to: address, callData: 'xxx'}, blockTag) and still always got the latest balance.
But I can get the correct historic ETH balance by calling provide.getBalance(address, blockTag).

Any help or idea will be greatly appreciated !
Thanks

[zemse]

What backend (eth node) are you using? For blockTag to work, the node should be run in archive mode. And it is observed that if the node is not run on archive mode, it silently ignores the block tag and returns you the current state's result.

[logan272]

@zemse thanks for your reply. yes, I'm using a Moralis archive node.

[eliotstock]

For anyone else using Alchemy and wondering if this works, it does, even in the free tier. Pass blockTag in the override as above and not blockNumber or blockHash.