Getting function results with decodeFunctionResult

[AlphabetsAlphabets]

  it("Should make a vote.", async () => {
    let contract = await hre.ethers.getContractAt("Election", contractAddress);
    // let result = await contract.vote("Proposal A");
    let contract_int = hre.ethers.Interface.from(contract.interface);
    
    let [owner, _] = await hre.ethers.getSigners()
    let new_contract = contract.attach(owner);

    let func_frag = contract_int.getFunction("vote", ["Proposal A"]);
    if (func_frag == null) {
      console.log("Null");
      fail("Function fragment shouldn't be null.");
    }

    let fn = new_contract.getFunction("vote");
    let results = await fn("Proposal A");

    console.log(results);
    console.log("RESULTS: ", contract_int.decodeFunctionResult(func_frag, results.data));

    expect(results.value).to.equal(0);
  });

I expect this to produce a result that is returned from the function but instead I get

     Error: invalid length for result data (value="0xfc36e15b0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000a50726f706f73616c204100000000000000000000000000000000000000000000", info={ "method": "vote", "signature": "vote(string)" }, code=BAD_DATA, version=6.13.7)

I tried decodeFunctionData and unsurprisingly, i returned "Proposal A". I'm not sure what else I can do. I came across this and I need to do "emit" but I'm not too sure what it is, also it's late so I don't really feel like doing more searching until I rest lol.

Also an additional question in this is the difference between connect and attach. The idea behind this contract is that I use a different wallet address to make a vote but I can't tell if it actually works or not. Any help is appreciated, thanks

[ricmoo]

The decodeFucntionResult will decode the result of an eth_call (or using a debug/trace API available on some services). Your above code looks like you are trying to decode the transaction .data field.

If you emit an event from your contract, then any emitted values will be available in the transaction receipt.

The .connect will return the same contract to a different Provider or Signer while the .attach will return the same contract but at a different address.

I am not sure about your situation, but my guess would be you want to provide some getters on your contract (i.e. pure or view methods), which you can then use eth_call on to access the Election.

[AlphabetsAlphabets]

The decodeFucntionResult will decode the result of an eth_call (or using a debug/trace API available on some services). Your above code looks like you are trying to decode the transaction .data field.

If you emit an event from your contract, then any emitted values will be available in the transaction receipt.

That's because I want to get the return value of the vote function. I assume there's a keyword or something I can tack on the solidity side to make it emit? This is the definition of the vote function:

    // function to cast a vote
    function vote(
        string memory proposal
    ) external onlyDuringVotingPeriod returns (uint status) {
        require(voterRegistry[msg.sender], "Not registered to vote");
        require(!hasVoted[msg.sender], "Already voted");
        require(
            bytes(proposals[proposal].name).length != 0,
            "Invalid proposal"
        );

        proposals[proposal].votes += 1;
        hasVoted[msg.sender] = true;

        return 0; // success
    }

The .connect will return the same contract to a different Provider or Signer while the .attach will return the same contract but at a different address.

So, a provider is someone who is calling the contract, a different provider would mean a different person would call the function in the contract. Is that right? While attach will move the contract to a different location.

I am not sure about your situation, but my guess would be you want to provide some getters on your contract (i.e. pure or view methods), which you can then use eth_call on to access the Election.

I'm trying to get the return result of the vote function as mentioned above.

[AlphabetsAlphabets]

@ricmoo I've managed to figure out emit.

  it("Should make a vote.", async () => {
    let contract = await hre.ethers.getContractAt("Election", contractAddress);

    contract.on("VoteStatus(string result)", (result: string) => {
      console.log("Status: ", result);
    });
    
    await contract.vote("Proposal A");
  
    expect(0).to.equal(0);
  });

The problem now is I don't know how to get result from the listener to outside the scope so it can be tested. I'm unsure of how to ensure that result is not undefined and then I'll use it at the bottom with expect to pass or fail the test.