How to get return value of smart contract by calling encoded function

[saarshah]

I have encoded function of my smart contract, which has methodID and parameters i.e. 0xf7ea7a3d4000000000000000000015000000000000000000ff7f0000b200000000f7ea7a............... Suppose, in this encoded function, there are also two arguments , one is uint and other is string. This encoded function actually is a getter (not changing status) of my contract (means in ABI its stateMutability =view) and also it return a value i.e. totalSupply. Now, i want to call this funciton through web3js/nodejs, as below. This code gives me transaction receipt/hash, as expected, but i am interested to retrieve the getter function return value i.e. totalSupply;

    try {
            await web3.eth.sendTransaction(
            {from:account1,
            to:myContAddr,
            data: myFunc
                }).then(function(res){
                  console.log("Normal Getter", res);
              });
        } catch (error) {
          console.log(" Normal Getters: ERROR !"); 
        }

One possible solution is to extract function Signature/methodID (which is easy for me) from given encoded function and its parameters (yet, not known to me how to decode parameters) and call function like this .. i.e.

try {
        res = await myContractInstance.methods[myFuncID](????).call({from: account1})  // without parameters
        console.log("Getter output", res);
      } catch (error) {
        console.log("Getter output: ERROR !", error);
      }

So, my questions are

1. how to decode parameters from above mentioned encoded function, to proceed as per my mentioned solution(if my solution is correct) ?
2. Or is there any other feasible/easy procedure to call such encoded (getter) function ?

[ryanio]

Hi @saarshah, unfortunately this is not a support forum so in the future the best place to ask and have your questions answered would be: https://ethereum.stackexchange.com

In my experience the easiest way to call the getter function you are looking for would be to instantiate the contract with web3.js using the jsonInterface and address:

const contract = new web3.eth.Contract(jsonInterface[, address][, options])

Docs link

The const contract should then have your contract methods on it, including getters if you set up your contract code correctly, which you can then call using methods.myMethod.call.

[saarshah]

Thanks for your answer... I already asked there, but no one is replying... I think, you did't got my point... I am asking help for my scenario, not for available easiest options.... i know them all. My scenario is to call contract function (which is in encoded form with all its parameters), can you please reconsider my question ? May be my question is demanding new feature, since I think, to call contract function with encoded values , such feature is not available in web3js, so far..v(if i am not wrong. ??????

[alcuadrado]

@saarshah I understand your frustration, but I think @ryanio was right on closing this issue. Your question is not related to this library.

What you are looking for is probably eth_call. You should call it manually through your web3 provider, using the encoded sig+params as data.