web3.eth.contract is not a function when making contract

Question

Whenever I try and make a contract, I get:

web3.eth.contract is not a function

I'm using this code:

const path = require('path');
const fs = require('fs');
const solc = require('solc');
const Web3 = require('web3');

const web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

// Compile the source code
let input = fs.readFileSync('./contracts/ProofOfExistence3.sol', 'utf8');
let output = solc.compile(input, 1);

let abi = JSON.parse(output.contracts[':ProofOfExistence3'].interface);
let bytecode = output.contracts[':ProofOfExistence3'].bytecode;

let gasEstimate = web3.eth.estimateGas({data: bytecode}).then(console.log);

// Contract object
let MyContract = web3.eth.contract(abi);

And if I only run this code below, I get undefined. The same code works in the browser but not in nodejs with the official web3 package.

const Web3 = require('web3');
const web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

console.log(web3.eth.contract);

Returns undefined.

Any ideas? I'm running "testrpc" locally.

Answer 1

Solution:

MyContract = new web3.eth.Contract(abi)

Docs https://web3js.readthedocs.io/en/1.0/web3-eth-contract.html#eth-contract

When using version 1.0.x you need to pass in the Application Binary Interface, i.e. abi. And use the new keyword.

Answer 2

I came this issue when I use web3 0.19.

For web3 1.0:

var Web3 = require('web3');
var web3 = new Web3(new Web3.providers.HttpProvider('http://127.0.0.1:8545/'));

new web3.eth.Contract(abiArray, contract_address, {from: address})

Answer 3

As Ismael suggested, setting the web3 version to 0.20.0 in my package.json allowed me to use this code.

npm install ethereumjs-testrpc [email protected]

Ideally, I would update my code to work with latest package but happy with this solution for now.

Answer 4

Adding to answer from @David

Smartcontract with web3 1.0.0-beta.31

In 1.0.0-beta... most is handled via Promises now, hence you could do:

var MyContract = new web3.eth.Contract({abi}, '0x123....', {
    from: '0x456...', // default from address
    gasPrice: '20000000000' // default gas price in wei, 20 gwei in this case
});

Example: Get Token Balance:

MyContract.methods.balanceOf('0x456...').call()
    .then(function(result){
    //the result holds your Token Balance that you can assign to a var
    var myTokenBalance = result;
    return result;
});

• Where {abi} is the ABI Interface of your Contract 0x123.....
• Where 0x123.... is the address of your Contract.
• Where 0x456.... is the address of your Ethereum Account that holds the Tokens (i.e. the ETH account you wish to retrieve its Token Balance from)

Note: I am using the IPC Provider geth.ipc to interact with my node (as I am on the same PC, localhost, hence more save instead of using HTTP request).

  if (typeof web3 !== 'undefined') {
    web3 = new Web3(web3.currentProvider);
  } else {
    var net = require('net');
    var web3 = new Web3('/home/yourHomeFolder/.ethereum/geth.ipc', net);
  };

That way you shouldn't get the error anymore

web3.eth.contract is not a function

Answer 5

Requires c capital of contract(Here: web3.eth.Contract), So it should be

var contractAbi = new web3.eth.Contract(abi)

look that is C and not c in: web3.eth.Contract

Answer 6

Installing web3 version 0.20.0 will resolve the issue. To install,

npm install ethereumjs-testrpc [email protected]

Answer 7

I have also answered it here

You just need to install a stable version of Web3:

npm install web3@^0.19.0 --save