Web3.py – How to Decode Log[‘data’] HexBytes from a Solidity Event Using Web3.py

I need help pulling zkEVM log data from testnet.

I have this simple solidity event in my smart contract (https://testnet-zkevm.polygonscan.com/address/0x98544219dd60eCc071302dAfBfce22F74334f244) that I deployed to the zkEMV testnet:

event LogData(
    uint256 indexed amount,
    string reason,
    address donatorAddress,
    uint256 timestamp
);

With the code below, I was able to iterate over the blocks and retrieve the event logs. But I can't read the second event argument (reason) as a string. It's written as hexBytes data: b'\x00\x00\x00…

Can someone please help me decode the event's reason which is inside the log['data'], on liine 49 of the code.

I tried using Web3.to_text(log['data']) and many others proposed solution but I wasn't able to decode it. The decoded data from both logs should be the following strings: "testnow" and "for adam"

from dash import Dash, html, callback, clientside_callback, Output, Input, State, no_update
import dash_bootstrap_components as dbc
from web3 import Web3
import json


app = Dash(__name__, external_stylesheets=[dbc.themes.CYBORG], external_scripts=[{'src': '../static/signerinfo.js', 'type':'module'}])
app.layout = dbc.Container([
    html.H1('Donation Decentralized Application'),

    dbc.Button("See donations over 45 wei", id="get-data", color='info', n_clicks=0),
    html.Div(id='placeholder', children=""),
    html.Div(id='placeholder2', children=""),

])


@callback(
    Output("placeholder2", "children"),
    Input("get-data", "n_clicks"),
    prevent_initial_call=True,
)
def access_data(alert_text):
    public_zkevm_rpc = 'https://rpc.public.zkevm-test.net'
    w3 = Web3(Web3.HTTPProvider(public_zkevm_rpc))
    print(w3.is_connected())
    abi = json.loads(
        '[{"inputs": [],"stateMutability": "payable","type": "constructor"},{"anonymous": false,"inputs": [{"indexed": true,"internalType": "uint256","name": "amount","type": "uint256"},{"indexed": false,"internalType": "string","name": "reason","type": "string"},{"indexed": false,"internalType": "address","name": "donatorAddress","type": "address"},{"indexed": false,"internalType": "uint256","name": "timestamp","type": "uint256"}],"name": "LogData","type": "event"},{"inputs": [{"internalType": "string","name": "donationReason","type": "string"}],"name": "offerDonation","outputs": [],"stateMutability": "payable","type": "function"},{"inputs": [],"name": "onlineEducator","outputs": [{"internalType": "address payable","name": "","type": "address"}],"stateMutability": "view","type": "function"}]')
    address = w3.to_checksum_address(
        '0x98544219dd60eCc071302dAfBfce22F74334f244')
    contract = w3.eth.contract(address=address, abi=abi)


    event_signature = "LogData(uint256,string,address,uint256)"
    over_45_wei = []
    # Iterate over the blocks from earliest to latest and retrieve the event logs
    for block_number in range(1444600, 1444700):
        logs = w3.eth.get_logs({
            "address": '0x98544219dd60eCc071302dAfBfce22F74334f244',
            "fromBlock": block_number,
            "toBlock": block_number,
            "topics": [w3.keccak(text=event_signature).hex()]
        })

        for log in logs:
            print(log)
            event_data = {
                "amount": int.from_bytes(log['topics'][1], byteorder='big'),
                "reason": log["data"],
            }
            print(event_data['amount'])
            print(event_data['reason'])

            if event_data['amount'] > 45:
                over_45_wei.append(event_data['amount'])
    print(over_45_wei)

    return no_update


if __name__ == '__main__':
    app.run(debug=True)

The code above is fully functional. For it to run on your computer, all you need to do is:

1. save the code as a .py file
2. pip install dash
3. pip install dash-bootstrap-components
4. pip install web3