Get the events of a call to another contract.

[ddnexus]

I am trying to get the same event emitted from one contract, also when I call it from another contract.

contract MyA {
    event MyEvent(uint count);

    function myFunction() public {
        emit MyEvent(123);
    }
}

contract MyB {
    function callMyFunction(address myAAddress) public {
        bytes memory data = abi.encodeWithSignature("myFunction()");
        (bool success, bytes memory transaction) = address(myAAddress).call(data);
        require(success);
    }
}

const myA = await (await eth.getContractFactory("MyA")).deploy() as MyA;
const txA = await myA.myFunction();
const rxA = await txA.wait();
console.log(rxA.events);

const myB = await (await eth.getContractFactory("MyB")).deploy() as MyB;
const txB = await myB.callMyFunction(myA.address);
const rxB = await txB.wait();
console.log(rxB.events);

[
  {
    transactionIndex: 0,
    blockNumber: 2,
    transactionHash: '0x5a8f61dedf9501f415bd8eb4534dbbc1deb17d0057d60e9728c6363484bb890b',
    address: '0x5FbDB2315678afecb367f032d93F642f64180aa3',
    topics: [
      '0x6c2b4666ba8da5a95717621d879a77de725f3d816709b9cbe9f059b8f875e284'
    ],
    data: '0x000000000000000000000000000000000000000000000000000000000000007b',
    logIndex: 0,
    blockHash: '0x8931b4c77bcec6eda2a69981050fc4e3b0471cc9c4dc1dd5498d00df9a513b7b',
    args: [ BigNumber { value: "123" }, count: BigNumber { value: "123" } ],
    decode: [Function (anonymous)],
    event: 'MyEvent',
    eventSignature: 'MyEvent(uint256)',
    removeListener: [Function (anonymous)],
    getBlock: [Function (anonymous)],
    getTransaction: [Function (anonymous)],
    getTransactionReceipt: [Function (anonymous)]
  }
]

[
  {
    transactionIndex: 0,
    blockNumber: 4,
    transactionHash: '0xe4e9814f37efc275db29ad0495e983473ff0adf92ba489645cd5cdcf0356c4e2',
    address: '0x5FbDB2315678afecb367f032d93F642f64180aa3',
    topics: [
      '0x6c2b4666ba8da5a95717621d879a77de725f3d816709b9cbe9f059b8f875e284'
    ],
    data: '0x000000000000000000000000000000000000000000000000000000000000007b',
    logIndex: 0,
    blockHash: '0x818b14eb0b53c4bcf58f281ec2baf1e92d79f7f54d1689ebb00f8552e7176b70',
    removeListener: [Function (anonymous)],
    getBlock: [Function (anonymous)],
    getTransaction: [Function (anonymous)],
    getTransactionReceipt: [Function (anonymous)]
  }
]

The second one is missing the important parts to get the actual event, so it's likely not the way to do it :).
How should I do it?

Thank you

[ddnexus]

OK, I have found a way to make it read by ethers: if I declare the same event in both contracts it gets automatically added to the abi, even if it is never used in the contract, and even if the bytecode is exactly the same.

Is that the right way to do it, or is there a way to add it to the abi used by ethers (only when I actually need it) instead of adding it to the contract?

Thank you

[zemse]

Declaring the same events or custom errors multiple times in your solidity files is not ideal. This has been an issue TBH, but the solidity compiler is not sure if it should include the events declared in other contracts. I now think it makes more sense for dev tools to copy the events from the ABI, however, there isn't a helpful tool yet. Also, I think I saw some code that does this in a random project (link).

[ddnexus]

Thank you for the answer.

Declaring the same events or custom errors multiple times in your solidity files is not ideal. This has been an issue...

Interesting. Besides the fact that it's kind of out of place in a contract that does not use it, I have a hard time to find a possible issue. If it is not in the bytecode what kind of issue could it create?

[zemse]

Yeah, there is no extra bytecode so no cost is attached. But by "not ideal" I mean, it adds duplicate lines to the solidity source code, which can be definitely done, if another way is feasible i.e. copy the generated ABI in JS side.

By issue, I mean currently, ABI of a dependency contract is not included in self contract. And args not being present in the other event is the result of abi fragment for that event not being present. And solidity team is discussing if it should address this on the compiler level argotorg/solidity#13149, argotorg/solidity#13149. But I think this will cause a lot of unnecessary events/errors to be included, but maybe this will also promote the usage of minimal interfaces instead of just using full ones.