Interface parseLog throws error

[iphyman]

Ethers Version

5.6.9

Search Terms

interface, parseLog

Describe the Problem

Am getting logs from the blockchain by making RPC call to my private node using eth_getTransactionReceipt method, after which I filter out the event topics am interested in (ERC 721 Transfer events).

With some logs everything works fine but at some other logs I get data out-of-bound error. I have looked through other similar issues non seems to fix the error or maybe there is something am still missing.

Am only interested in decoding ERC721 compliant tokens

Code Snippet

const logs = [
{
      address: '0x3a7711989386601293d1fc1bd09e1eeed24d3d1e',
      topics: [
        '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
        '0x0000000000000000000000000000000000000000000000000000000000000000',
        '0x0000000000000000000000007e31af176da39a9986c8f5c7632178b4acf0c868',
      ],
      data: '0x00000000000000000000000000000000000000000003d8ad014e6c1dc6400000',
      blockNumber: 9212671,
      transactionHash:
        '0xc270bf62d267a7fe8a70415b4590ba1e987a428bf6d85672415283f600f4cb7a',
      transactionIndex: 0,
      blockHash:
        '0x8ad2e0586d7f55b4655217c0f33890888e48adf1cd5112a2621457dc6935a72d',
      logIndex: 1,
      removed: false,
    }
]

const iface = new utils.Interface(ERC721Abi);

const events = logs.map((log) => {
 return {
  contractAddress: log.address,
  args: iface.parseLog(log)
}
})

console.log(JSON.stringify(events))

Contract ABI

[{
        "anonymous": false,
        "inputs": [{
                "indexed": true,
                "internalType": "address",
                "name": "owner",
                "type": "address"
            },
            {
                "indexed": true,
                "internalType": "address",
                "name": "approved",
                "type": "address"
            },
            {
                "indexed": true,
                "internalType": "uint256",
                "name": "tokenId",
                "type": "uint256"
            }
        ],
        "name": "Approval",
        "type": "event"
    },
    {
        "anonymous": false,
        "inputs": [{
                "indexed": true,
                "internalType": "address",
                "name": "owner",
                "type": "address"
            },
            {
                "indexed": true,
                "internalType": "address",
                "name": "operator",
                "type": "address"
            },
            {
                "indexed": false,
                "internalType": "bool",
                "name": "approved",
                "type": "bool"
            }
        ],
        "name": "ApprovalForAll",
        "type": "event"
    },
    {
        "anonymous": false,
        "inputs": [{
                "indexed": true,
                "internalType": "address",
                "name": "from",
                "type": "address"
            },
            {
                "indexed": true,
                "internalType": "address",
                "name": "to",
                "type": "address"
            },
            {
                "indexed": true,
                "internalType": "uint256",
                "name": "tokenId",
                "type": "uint256"
            }
        ],
        "name": "Transfer",
        "type": "event"
    },
    {
        "inputs": [{
                "internalType": "address",
                "name": "to",
                "type": "address"
            },
            {
                "internalType": "uint256",
                "name": "tokenId",
                "type": "uint256"
            }
        ],
        "name": "approve",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "address",
            "name": "owner",
            "type": "address"
        }],
        "name": "balanceOf",
        "outputs": [{
            "internalType": "uint256",
            "name": "balance",
            "type": "uint256"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "uint256",
            "name": "tokenId",
            "type": "uint256"
        }],
        "name": "getApproved",
        "outputs": [{
            "internalType": "address",
            "name": "operator",
            "type": "address"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
                "internalType": "address",
                "name": "owner",
                "type": "address"
            },
            {
                "internalType": "address",
                "name": "operator",
                "type": "address"
            }
        ],
        "name": "isApprovedForAll",
        "outputs": [{
            "internalType": "bool",
            "name": "",
            "type": "bool"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [],
        "name": "name",
        "outputs": [{
            "internalType": "string",
            "name": "",
            "type": "string"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "uint256",
            "name": "tokenId",
            "type": "uint256"
        }],
        "name": "ownerOf",
        "outputs": [{
            "internalType": "address",
            "name": "owner",
            "type": "address"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
                "internalType": "address",
                "name": "from",
                "type": "address"
            },
            {
                "internalType": "address",
                "name": "to",
                "type": "address"
            },
            {
                "internalType": "uint256",
                "name": "tokenId",
                "type": "uint256"
            }
        ],
        "name": "safeTransferFrom",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "inputs": [{
                "internalType": "address",
                "name": "from",
                "type": "address"
            },
            {
                "internalType": "address",
                "name": "to",
                "type": "address"
            },
            {
                "internalType": "uint256",
                "name": "tokenId",
                "type": "uint256"
            },
            {
                "internalType": "bytes",
                "name": "data",
                "type": "bytes"
            }
        ],
        "name": "safeTransferFrom",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "inputs": [{
                "internalType": "address",
                "name": "operator",
                "type": "address"
            },
            {
                "internalType": "bool",
                "name": "_approved",
                "type": "bool"
            }
        ],
        "name": "setApprovalForAll",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "bytes4",
            "name": "interfaceId",
            "type": "bytes4"
        }],
        "name": "supportsInterface",
        "outputs": [{
            "internalType": "bool",
            "name": "",
            "type": "bool"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [],
        "name": "symbol",
        "outputs": [{
            "internalType": "string",
            "name": "",
            "type": "string"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "uint256",
            "name": "tokenId",
            "type": "uint256"
        }],
        "name": "tokenURI",
        "outputs": [{
            "internalType": "string",
            "name": "",
            "type": "string"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
                "internalType": "address",
                "name": "from",
                "type": "address"
            },
            {
                "internalType": "address",
                "name": "to",
                "type": "address"
            },
            {
                "internalType": "uint256",
                "name": "tokenId",
                "type": "uint256"
            }
        ],
        "name": "transferFrom",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    }
]

Errors

const error: any = new Error(message);                           ^
Error: data out-of-bounds (length=64, offset=96, code=BUFFER_OVERRUN, version=abi/5.6.4)

Environment

node.js (v12 or newer)

Environment (Other)

No response

[ricmoo]

Unfortunately, because Solidity does not include the indexed keyword when computing topic hashes, the ERC-20 and ERC-721 Transfer events share the identical topic hash.

As a result, a filter for one will also get the other, and they are incompatible (as ERC-721 indexes the tokenId and ERC-20 does not index the equivalent field amount).

If you have a contract that emits both, you will need to further refine by some other method, such as by topic length or the presence of data. You can also trap errors and possibly discard them, depending on your use case.

Does that make sense? It would have been nice if ERC-721 also didn’t try to be compatible with ERC-20. :s

[iphyman]

Thanks @ricmoo , it does make sense, I did observe that the logs that decodes perfectly without throwing errors have no data (0x).
Refining by data did the magic.

[ancil-t]

Thanks for clarifying this @ricmoo. This is something that had puzzled me for a long time but I never got around to asking about it.

[ChrisCates]

Is it possible we could get some patterns thrown in the cookbook that demonstrate how to properly parse ERC721 and ERC20 tokens without try catch statements being dinged constantly?