Problem with running truffle code with node.js

Question

I am trying to run truffle code with Node.JS in the backend to deploy contracts. I want to be able to do this interactively and I am intending to use the Express Library to interact with the Node backend.

However, in the first instance I am just trying to run a .js in node to deploy a contract. I can do so easily in the deploy script but want to be able to do it on the fly. Here is the code I am talking about:

const Web3 = require("web3");
const HDWalletProvider = require("truffle-hdwallet-provider");
const mnemonic = "..."

var httpProvider = new Web3.providers.HttpProvider('https://ropsten.infura.io/v3/<my API>');
var provider = new HDWalletProvider(mnemonic, httpProvider);

var contract        = require("truffle-contract");
var myContractJSON  = require('./build/contracts/Insurer.json');

// Read JSON and attach RPC connection (Provider)
var myContract = contract(myContractJSON);
myContract.setProvider(provider);

myContract.new("0x20202020202020202020204931303031", "0x20202020202020202020436f66616365")
    .then(function(instance) {
    return instance.getInsurerInfo.call()
    }).then(function(result) {
        console.log(result[0], result[1]);
        res.send('Insurer contract made successfully: '+result[0]+' '+result[1]);
        }, function(error) {
    console.log(error);
    });

and here is the relevant contract code:

    contract Insurer {
    bytes16 public insurerUIC;  
    bytes16 public insurerName;

    constructor(bytes16 _insurerUIC, bytes16 _insurerName) public {
        insurerUIC      = _insurerUIC;
        insurerName     = _insurerName;
        } // constructor(bytes16 _insurerUIC, bytes16 _insurerName) public {

    function () payable external {
        // fallback function to receive funds
    } // function () payable external {

    function getInsurerInfo() view public returns (bytes16, bytes16) {
        return (insurerUIC, insurerName);
        } // function getInsurerInfo() view public returns (bytes16, bytes16)

    } // contract Insurer {

The contract takes 2 parameters. When I run the code above it seems to run but nothing actually happens.

Any idea what is wrong? Also how can I debug Node code without being able to use the console?

Sorry for beginner questions but I am struggling!

Thanks,

Phil

Answer 1

There are two issues with your code. The first one is preventing the contract to be deployed: you must pass the "from" address whenever you send a transaction to the blockchain (as opposed to a call). So, the instantiation should look like this:

myContract.new("0x20...31", "0x20...65", { from: provider.getAddress() })

The other issue is that you are not listening to the first response you'll get, which is the txHash. That response will come much earlier than the contract's instance. So, even after you add the "from" address, it will still look like nothing is happening because you're waiting for the deploy to be mined.

In order for you to get this first response, you should add the following:

.once('transactionHash', function(hash) {
    console.log("TxHash: " + hash);
})

That should happen pretty fast, and then you can wait another 30 seconds or so to get the result you expect.

The final code is:

const Web3 = require('web3');
const HDWalletProvider = require("@truffle/hdwallet-provider");

require('dotenv').config();
const provider = new HDWalletProvider(process.env.PRIVATE_KEY, process.env.INFURA_URL);

const contract = require('@truffle/contract');
const artifacts = require('./../contracts/Insurer.json');

var myContract = contract(artifacts);
myContract.setProvider(provider);

myContract.new("0x20202020202020202020204931303031", "0x20202020202020202020436f66616365", { from:provider.getAddress() })
        .once('transactionHash', function(hash) {
            console.log("TxHash: " + hash);
        }).then(function(instance) {
            return instance.getInsurerInfo.call()
        }).then(function(result) {
            console.log(result[0], result[1]);
        }, function(error) {
            console.log(error);
        });

Note that I'm using a private key instead of a mnemonic to setup the HDWallet provider, but that should make no difference. Also, I'm using the updated versions of @truffle/hdwallet-provider and @truffle/contract, but I do think that's irrelevant too.

Also how can I debug Node code without being able to use the console?

Try nodemon. That's what I'm using, it prints just fine.

Hope it helps.