I would like to use web3.py instead of using the etherscan write contract function available in ethercan.io, Etherscan.io write contract function

Is this possible? if yes can someone please show me a sample. The contract address of the sample above: https://etherscan.io/token/0x2b591e99afe9f32eaa6214f7b7629768c40eeb39#writeContract

1 Answer 1


"Writing to contracts" is a somewhat confusing term from Etherscan.

It is doing a transaction to a smart contract address and function.

If look Web3.py examples the example that calls the function setVar() is writing to the contract.

import sys
import time
import pprint

from web3.providers.eth_tester import EthereumTesterProvider
from web3 import Web3
from solc import compile_source

def compile_source_file(file_path):
   with open(file_path, 'r') as f:
      source = f.read()

   return compile_source(source)

def deploy_contract(w3, contract_interface):
    tx_hash = w3.eth.contract(

    address = w3.eth.getTransactionReceipt(tx_hash)['contractAddress']
    return address

w3 = Web3(EthereumTesterProvider())

contract_source_path = 'contract.sol'
compiled_sol = compile_source_file('contract.sol')

contract_id, contract_interface = compiled_sol.popitem()

address = deploy_contract(w3, contract_interface)
print("Deployed {0} to: {1}\n".format(contract_id, address))

store_var_contract = w3.eth.contract(

gas_estimate = store_var_contract.functions.setVar(255).estimateGas()
print("Gas estimate to transact with setVar: {0}\n".format(gas_estimate))

if gas_estimate < 100000:
  print("Sending transaction to setVar(255)\n")
  tx_hash = store_var_contract.functions.setVar(255).transact()
  receipt = w3.eth.waitForTransactionReceipt(tx_hash)
  print("Transaction receipt mined: \n")
  print("Was transaction successful? \n")
  print("Gas cost exceeds 100000")
  • thanks for the sample, at first i get this error ImportError: cannot import name 'compile_source' from 'solc'. If i get through this error, would it be possible to give me a hand to actually apply it to my original sample function?
    – Ash
    Mar 19, 2020 at 22:22
  • Yes. You need to compile your smart contracts using solc. Based on the outputted ABI files you can construct web3.Contract code in Python. Mar 20, 2020 at 11:26

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