TypeError: Cannot read property 'on' of undefined, can't access event from nodejs

[stiv-yakovenko]

This is my source code in nodejs:

var Web3 = require('web3');
var web3 = new Web3();
web3.setProvider(new web3.providers.HttpProvider('http://localhost:8545'));
var abi = ...
var contract = new web3.eth.Contract(abi, MAIN_CONTRACT_ID);
contract.events.Evt({fromBlock: 0, toBlock: 'latest'},function () {
}).on('data',function (evt) {
        console.log("evt",evt);
    });

But I get this crash:

TypeError: Cannot read property 'on' of undefined
    at Subscription.subscribe (C:\Users\steve\Dropbox\Projects\dsd\dsd\web3test\node_modules\web3\packages\web3-core-subscriptions\src\subscription.js:199:45)
    at Contract._on (C:\Users\steve\Dropbox\Projects\dsd\dsd\web3test\node_modules\web3\packages\web3-eth-contract\src\index.js:623:18)

contract.Evt is undefined for me, contract is defined and contains contract.events.Evt.

How can I fix this?

[jdkanani]

I cannot reproduce this.

[stiv-yakovenko]

@jdkanani here is a full code:

https://gist.github.com/stiv-yakovenko/26994bbe32457bb69ef7694e98a5e7cf

Hopefully it can help you to reproduce this. I am on test-net.

[frozeman]

The problem seems to be with setProvider, which doesn't propagate down the provider. i will fix it.
But in any case you can't use HTTP to subscribe, as it doesn't provide push and we don't have polling for subscriptions yet.
Please use Websockets.

And yes, event s are now under the event property

[jdkanani]

@frozeman Why not use direct methods/events - contract.transfer (like earlier) instead of contract.methods.transfer? Before it was making more sense. Any specific reason?

Apart from that, how one can get parsed log from raw log object from contract object? Example: contract.events.Transfer.parse(rawLog)? where rawLog is object with topics array etc..

[frozeman]

@jdkanani the reason to put it under a separate property is that you can define any name on your contract object, which could interfere with native functions like deploy etc. So its safer to put it in a separate property. We also expose now the function names and signatures, so to make sure you can access all functions on a smart contract, even the ones with different parameters.

For contract raw logs you should have the raw property in the log itself.
I don't know about any parse function

[jdkanani]

@frozeman Makes sense. Thanks.

For log related, when you do getTransactionReceipt, you receipt with logs (having topics and data properties in it). I want to parse that log with appropriate event. So I can get appropriate returnValues. Receipt could be retrieved from anywhere, example - private server or using getTransactionReceipt method

Currently, I am using this (little hack):

var transferEvent = ct.events.Transfer();
var result =  transferEvent.options.subscription.outputFormatter(receipt.logs[0]); // receipt object from server or `getTransactionReceipt` get method
console.log(result.returnValues._to, result.returnValues._from, result.returnValues._value);

Is there any other way to do so? Like - ct.events.Transfer.outputFormatter(receipt.logs[0]) or other way without creating event object?