When do Events include decoded args?

[novaknole]

I've been trying to get the logs from the transaction receipt.

I do this:

let contract = await (await ethers.getContractFactory('contract')).deploy()

let tx = await contract.function();

const { events } = await tx.wait();

Sometimes, the events have the event and args parameters in the returned object and it helps me to do something like this directly:

const args = events.find(({ event }) => event === 'EventName').args

but sometimes, for some contracts, event and args don't exist on the Event object. I am wondering why, because I've looked into the contracts and they emit the same kind of events.

Question 1: I'd appreciate if you could let me know what's the issue here and why sometimes it doesn't include event and args.

Question 2: What's the alternative and easiest way ? I know about the interface , but maybe there's a cleaner way in 2021.

Thanks in advance.

[ricmoo]

The event and args are included only if there is enough information in the log and Interface to derive this.

If the log's topic0 matches an event topic hash in the Interface (and there are no data errors), it will be added, otherwise it won't be.

Feel free to post some examples though, if you feel there is a case where the Event is defined in the Interface but the args and event aren't present.

[ricmoo]

Have you tried combining the event ABI into a single ABI set? I think that should allow Second’s events to be emitted from the contract object…

[novaknole]

@ricmoo That could work for sure, but

I am using it like this..

const GovernTokenFactory = await ethers.getContractFactory(
      'First'
    )

So where would I combine it exactly ?

[novaknole]

@ricmoo

The problem is that I can't pass anything to getContractFactory. I am using hardhat-ethers. I contacted them and they said, it's something that should be done on ethers.js side.

Maybe there's a quick way of solving this.

I really don't want to create a new WrapperContract.sol which extends my First contract and also adds that event there and then I use WrapperContract.sol in my tests.

Any other way ?

[zemse]

You can consider this way if it works

const firstArtifact = await hre.artifacts.readArtifact('First');
const secondArtifact = await hre.artifacts.readArtifact('Second');

const firstAbi = [
  ...firstArtifact.abi, 
  secondArtifact.abi.filter((f: ethers.utils.Fragment) => f.type === 'event')
]

const F = new ethers.ContractFactory(firstAbi, firstArtifact.bytecode);
F.deploy( ...args );

[novaknole]

@zemse made my day.

Thanks a lot

[ricmoo]

(moving to discussions)

[novaknole]

@ricmoo

I really don't want to loop through all the events, since there're many.. So looking for alternatives.

[novaknole]

@ricmoo

I also tried this...

const iface = new ethers.utils.Interface([
      'event MintedMerkle(address indexed distributor, bytes32 indexed merkleRoot, uint256 totalAmount, bytes tree, bytes context)'
    ])
    const { events } = await tx.wait()
    const a = events.map((log) => iface.parseLog(log));
    console.log(a, ' tried this');
    ```

but I got

> Error: no matching event (argument="topichash", value="0xc87aeafc6e4ae6202adf4f08a76769119ae93cc129c0e0cbac08a118bc18e1ce", code=INVALID_ARGUMENT, version=abi/5.1.2)

[wellitongervickas]

yes, me tooo