I am using Truffle to deploy a contract on Ganache and retrieve the contract in an express app. While I can get the contract instance and it can console.log a list of function object, the function cannot be called in the code.

Here is my contract:

contract Vote{
    uint dem = 0;
    uint pub = 0;

    constructor() public {
        dem = 0;
        pub = 0;

    function vote(uint v) public {
        if(v == 1){
            pub += 1;
        } else {
            dem += 1;

    function getWinner() public view returns (uint) {
        if(dem > pub){
            return dem;
        } else {
            return 0 - pub;

Code call the function:

var voteAbi = [{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"constant":false,"inputs":[],"name":"getWinner","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"internalType":"uint256[]","name":"v","type":"uint256[]"}],"name":"vote","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"}]
web3.eth.defaultAccount = web3.eth.accounts[0]
var voteContract = web3.eth.contract(voteAbi);
var voteInstance = voteContract.at("0x0711217536458a37580e669de781554ce33236c24711d351d446a437e16ae058");

All the three lines call the function vote result in the Foreach problem. I am new to web3 and blockchain! Any ideas on what could go wrong here?

  • 1
    What is the version of your web3?
    – Masoud jt
    Nov 30 '20 at 6:36
  • You need to put those lines in an async function, and add await in some of them (the last 3 for sure, the one before them if your web3.js version is 1 or higher). Nov 30 '20 at 6:43
  • in addition to what @goodvibration said. you need to change web3.eth.contract(voteAbi) to web3.eth.Contract(voteAbi) in web3 version 1 or higher. (notice that Contract has a capital C )
    – Masoud jt
    Nov 30 '20 at 8:12
  • @Masoudjt: You're wrong about the await. This is just the creation of a local web3.eth.Contract object. There is no interaction with the remote node here, hence no need to asynchronously await for it to complete. Nov 30 '20 at 8:13
  • @goodvibration yes. thanks. edited.
    – Masoud jt
    Nov 30 '20 at 8:14

It is a problem caused by Truffle. When I move to remix and deploy the contract in my ganache-cli, it works.

  • Don’t unlock accounts, better to sign the transactions with the private key.
    – Majd TL
    Mar 12 at 8:03

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