Python class used to check balance of a NFT token on a wallet

nftutils.py

from web3 import Web3

class NFTUtils:
    def __init__(self, w3, contract_address):
        self.w3 = w3
        self.contract_address = self.w3.to_checksum_address(contract_address)
    
    # La usamos con una ABI simple para comprobar si admite unos parámetro o no
    # Y así detectamos el tipo de contrato
    def _call_simple_function(self, function_name, *args):
        # Utility method to call a contract function and handle exceptions
        try:
            contract = self.w3.eth.contract(address=self.contract_address, abi=self._get_abi(function_name))
            return contract.functions[function_name](*args).call()
        except Exception as e:
            print(f"Error calling function {function_name}: {e}")
            return None

    # Proporciona un ABI mínimo para las funciones balanceOf, balanceOfBatch, y supportsInterface. 
    # Se adapta según la función que se necesite llamar.
    def _get_abi(self, function_name):
        # Provide a minimal ABI for calling functions
        if function_name in ['balanceOf', 'balanceOfBatch']:
            return [{
                "constant": True,
                "inputs": [{"name": "account", "type": "address"}, {"name": "id", "type": "uint256"}] if function_name == 'balanceOf' else [{"name": "accounts", "type": "address[]"}, {"name": "ids", "type": "uint256[]"}],
                "name": function_name,
                "outputs": [{"name": "", "type": "uint256"}] if function_name == 'balanceOf' else {"name": "", "type": "uint256[]"},
                "payable": False,
                "stateMutability": "view",
                "type": "function"
            }]
        elif function_name == 'supportsInterface':
            return [{
                "constant": True,
                "inputs": [{"name": "interfaceId", "type": "bytes4"}],
                "name": function_name,
                "outputs": [{"name": "", "type": "bool"}],
                "payable": False,
                "stateMutability": "view",
                "type": "function"
            }]
        return []

    # Verifica si el contrato soporta una interfaz específica utilizando la función supportsInterface.
    def _supports_interface(self, interface_id):
        try:
            return self._call_simple_function('supportsInterface', interface_id)
        except Exception as e:
            print(f"Error checking interface support: {e}")
            return False

    # Identifica si el contrato es ERC-721 o ERC-1155 basándose en el soporte de interfaces.
    def detect_contract_type(self):
        # Check ERC-721 and ERC-1155 support
        ERC721_INTERFACE_ID = '0x80ac58cd'  # ERC-721
        ERC1155_INTERFACE_ID = '0xd9b67a26'  # ERC-1155

        if self._supports_interface(ERC721_INTERFACE_ID):
            return 'ERC-721'
        elif self._supports_interface(ERC1155_INTERFACE_ID):
            return 'ERC-1155'
        else:
            return 'Unknown'

    # Verifica el balance de NFT en una wallet dada el tipo de contrato detectado.
    def is_nft_in_wallet(self, wallet_address, token_id=None):
        contract_type = self.detect_contract_type()
        # print(f"Detected contract type: {contract_type}")

        if contract_type == 'ERC-721':
            # Check if the NFT is in the wallet for ERC-721
            balance = self._call_simple_function('balanceOf', wallet_address)
            if balance is None:
                raise ValueError("Failed to retrieve balance for ERC-721")
            return balance > 0

        elif contract_type == 'ERC-1155':
            # Check if the NFT is in the wallet for ERC-1155
            if token_id is None:
                raise ValueError("token_id is required for ERC-1155")
            balance = self._call_simple_function('balanceOf', wallet_address, token_id)
            if balance is None:
                raise ValueError("Failed to retrieve balance for ERC-1155")
            return balance > 0

        else:
            raise ValueError("Unknown contract type")

Description

This Python script allows you to check if an NFT is present in a wallet on EVM-compatible blockchains. It supports both ERC-721 and ERC-1155 standards.

The core of the solution involves:

• Using a Simple ABI: We utilize a simplified ABI that includes only the balanceOf function. This approach allows us to interact with both ERC-721 and ERC-1155 contracts with a single ABI definition.
• Interface Detection: To determine whether a contract implements ERC-721 or ERC-1155, we use the supportsInterface function. This function checks if the contract supports specific interfaces by their unique identifier.

Sample of use:

from web3 import Web3

w3 = Web3(Web3.HTTPProvider("https://1rpc.io/base"))
contract_address_nft="0x2aa80a13395425ef3897c9684a0249a5226ea779"
wallet_address="0xEAa73d06320C1aCb1F7C947e1B6c5c9F326c2C3d"
nft_token_id=2

try:
    nftutils=NFTUtils(w3, contract_address_nft)
    return nftutils.is_nft_in_wallet(wallet_address, nft_token_id)
except ValueError as e:
    print(f'Error: {e}')