Transact Tokens on the Polygon Chain: Solving the Issue with Metamask and Web3

If you’re looking to automatically transfer tokens from multiple Metamask wallets into one central wallet on the Polygon chain, you’re not alone. Many users want to interact with tokens on Polygon in a similar way they would with tokens on the Ethereum blockchain, but there are some key differences and challenges you may face when dealing with tokens on Polygon.

Polygon Chain and ERC20 Tokens:

Polygon is a Layer 2 scaling solution for Ethereum, designed to provide faster and cheaper transactions. While it is closely linked to Ethereum and uses the same Ethereum-compatible standards, the key difference is that Polygon operates as its own network, meaning that you need to connect to the Polygon chain specifically, rather than the Ethereum mainnet, to interact with assets on Polygon.

The token you’re trying to interact with is an ERC20 token, which is a common token standard on both Ethereum and Polygon. While the token itself might follow the same standards, the key difference lies in the network you’re connecting to: Ethereum’s mainnet vs Polygon’s network. Since you want to automate token transfers on Polygon, the error you’re encountering might stem from an incorrect network setup, ABI issues, or simply a mismatch in how you are referencing the chain.

Identifying the Error in Your Code:

The code you’ve provided gives an error: “Could not transact with/call contract function, is contract deployed correctly and chain synced?” This error typically suggests that there is an issue with the connection to the blockchain or the contract deployment.

Looking at your code, here are a few potential issues:

• Incorrect Network Provider: Your script is using an Infura URL that connects to Ethereum’s mainnet:

codew3 = Web3(HTTPProvider("https://mainnet.infura.io/v3/..."))

• However, since your token is on the Polygon network, you need to change the provider URL to one that connects to the Polygon network, such as:

codew3 = Web3(HTTPProvider("https://polygon-rpc.com"))

• Missing ABI: The token you’re trying to interact with is an ERC20 token on the Polygon chain, and you mention that you don’t see an ABI for it. Typically, ERC20 tokens have a standard ABI, which you can use to interact with them. Since you don’t have the specific ABI, you can use a standard ABI for ERC20 tokens, which includes functions like balanceOf, transfer, and approve. Here’s a minimal version of the standard ERC20 ABI

codeEIP20_ABI = [
    {
        "constant": True,
        "inputs": [{"name": "_owner", "type": "address"}],
        "name": "balanceOf",
        "outputs": [{"name": "balance", "type": "uint256"}],
        "payable": False,
        "stateMutability": "view",
        "type": "function",
    },
    {
        "constant": False,
        "inputs": [
            {"name": "_to", "type": "address"},
            {"name": "_value", "type": "uint256"},
        ],
        "name": "transfer",
        "outputs": [{"name": "success", "type": "bool"}],
        "payable": False,
        "stateMutability": "nonpayable",
        "type": "function",
    }
]

• Address Recognition: Ensure the contract address you’re using is correct and deployed on the Polygon chain. You can double-check this on PolygonScan (https://polygonscan.com/). In your case, the token’s contract address is:

code0x3a9A81d576d83FF21f26f325066054540720fC34

• If the contract address is correct, ensure that your Metamask wallet is properly configured to connect to the Polygon network and that you have the right network selected.

A Corrected Example of Code:

Once you have the correct provider and ABI, your updated code might look like this:

codefrom web3 import Web3
from web3.middleware import geth_poa_middleware

# Connect to Polygon network
w3 = Web3(Web3.HTTPProvider("https://polygon-rpc.com"))

# Enable PoA middleware for Polygon (important for public networks)
w3.middleware_stack.inject(geth_poa_middleware, layer=0)

# Define the contract address and ABI
contract_address = '0x3a9A81d576d83FF21f26f325066054540720fC34'

# Standard ERC20 ABI
EIP20_ABI = [
    {
        "constant": True,
        "inputs": [{"name": "_owner", "type": "address"}],
        "name": "balanceOf",
        "outputs": [{"name": "balance", "type": "uint256"}],
        "payable": False,
        "stateMutability": "view",
        "type": "function",
    },
    {
        "constant": False,
        "inputs": [
            {"name": "_to", "type": "address"},
            {"name": "_value", "type": "uint256"},
        ],
        "name": "transfer",
        "outputs": [{"name": "success", "type": "bool"}],
        "payable": False,
        "stateMutability": "nonpayable",
        "type": "function",
    }
]

# Initialize the contract
contract = w3.eth.contract(address=contract_address, abi=EIP20_ABI)

# Check balance of an address
n1 = '0xYourAddressHere'  # Replace with the address you want to check
raw_balance = contract.functions.balanceOf(n1).call()

# Print the balance (in wei)
print(f"Balance: {raw_balance}")

Additional Steps to Automate Transfers:

Once you can successfully interact with the token (i.e., check balances), you can extend this script to automate transfers between wallets. Here’s a simple flow for automating token transfers:

1. Get a list of wallet addresses that you want to transfer tokens from.
2. Check balances of each wallet.
3. If the balance is above a certain threshold, use the transfer function to send the tokens to your central wallet.

Here’s an example snippet that transfers tokens from one wallet to another:

codedef transfer_tokens(sender_private_key, sender_address, receiver_address, amount):
    nonce = w3.eth.getTransactionCount(sender_address)
    
    # Build the transaction
    txn = contract.functions.transfer(receiver_address, amount).buildTransaction({
        'chainId': 137,  # Polygon chain ID
        'gas': 2000000,
        'gasPrice': w3.toWei('30', 'gwei'),
        'nonce': nonce,
    })
    
    # Sign the transaction
    signed_txn = w3.eth.account.signTransaction(txn, sender_private_key)
    
    # Send the transaction
    txn_hash = w3.eth.sendRawTransaction(signed_txn.rawTransaction)
    return txn_hash

You’ll need to loop through your list of wallets, check balances, and then execute transfer_tokens accordingly.

Conclusion:

• Ensure you’re connecting to the correct Polygon network URL.
• Use a correct and valid ABI for ERC20 tokens.
• Make sure you have set up the PoA (Proof of Authority) middleware for Polygon’s chain.
• Once the balance check works, you can automate transfers using the transfer function.

By following these steps, you should be able to automate the process of transferring tokens between your Metamask wallets on the Polygon network seamlessly.