Hardhat - Cannot read properties of undefined (reading '0') error in event log

Question

I wanted to study the events on hardhat by following this lesson.

npx version: 9.5.1

node version: v12.22.9

Here's my contract code:

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.7;

contract SimpleStorage {

    uint256 favoriteNumber;
    event storedNumber(
        uint256 indexed oldNumber,
        uint256 indexed newNumber,
        uint256 addedNumber,
        address sender
    );

    function store(uint256 _favoriteNumber) public {
        emit storedNumber(
            favoriteNumber,
            _favoriteNumber,
            _favoriteNumber + favoriteNumber,
            msg.sender
        );
        favoriteNumber = _favoriteNumber;
    }

    function retrieve() public view returns (uint256) {
        return favoriteNumber;
    }
}

Here's my script:

deploy_and_store.js

async function main() {

    await hre.run("compile");

      // We get the contract to deploy
    const SimpleStorage = await hre.ethers.getContractFactory("SimpleStorage");
    const simpleStorage = await SimpleStorage.deploy();
    await simpleStorage.waitForDeployment();

    const transactionResponse = await simpleStorage.store(1);
    const transactionReceipt = await transactionResponse.wait();
    console.log(transactionReceipt);
    console.log(transactionReceipt.events[0]);
    
}

main().catch((error) => {
    console.error(error)
    process.exitCode = 1
  })

When I execute the command:

npx hardhat run scripts/deploy_and_store.js 

The output of console.log(transactionReceipt); is:

ContractTransactionReceipt {
  provider: HardhatEthersProvider {
    _hardhatProvider: LazyInitializationProviderAdapter {
      _providerFactory: [AsyncFunction (anonymous)],
      _emitter: [EventEmitter],
      _initializingPromise: [Promise],
      provider: [BackwardsCompatibilityProviderAdapter]
    },
    _networkName: 'hardhat',
    _blockListeners: [],
    _transactionHashListeners: Map(0) {},
    _eventListeners: []
  },
  to: '0x5FbDB2315678afecb367f032d93F642f64180aa3',
  from: '0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266',
  contractAddress: null,
  hash: '0x6c7f5c327bda60c98ec15ac8a4911f48e8cac977f9fb94d7e89871f08933a05d',
  index: 0,
  blockHash: '0xf64f2050788f46fb3064a709a1cfffac792dbabcfcf0388583f048507d868963',
  blockNumber: 2,
  logsBloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000040000000000000000000000000040020000000000000000000800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000010000000000000000000040000000000000000000000000000000040000000000000000000060000000000000000000000000000000000000000000000000000000000001000000',
  gasUsed: 46372n,
  blobGasUsed: undefined,
  cumulativeGasUsed: 46372n,
  gasPrice: 1767032241n,
  blobGasPrice: undefined,
  type: 2,
  status: 1,
  root: undefined
}

and the output of console.log(transactionReceipt.events[0]); is:

TypeError: Cannot read properties of undefined (reading '0')
    at main (..\scripts\deploy_and_store.js:19:42)

means that I can't see the event.

Can someone tell me where I'm wrong?

Thank you very much. Best regards!

Answer 1

Instead of events, it should be the logs array, inside the transactionReceipt object.

So, replace this:

console.log(transactionReceipt.events[0]);

with:

console.log(transactionReceipt.logs[0]);