How to listen permanently to events in a smart contract from node.js Application?

Question

I have a node js App which has the following code:

contract.getPastEvents('RequestCreated', function (error, event) { console.log(event); })
        .then(function (events) {
            console.log(events); 
        })

Once I run the node, I get an empty array.

My expectation is to get the value of the variable requestCount once the event in the smart contract is emited

    function createRequest(string memory _fileHash) public {
        requestCount++;
        fileHash[requestCount] = _fileHash;
        emit RequestCreated(requestCount);
    }

My question is how to listen to events occurring in the smart contract from a node js App?

I am using Web3 Version > 1, so the watch function is not the right one for me.

user_12545796 · Answer

There is an event.watch() functionality and a good tutorial online on how to use it. https://coursetro.com/posts/code/100/Solidity-Events-Tutorial---Using-Web3.js-to-Listen-for-Smart-Contract-Events

Snipped out of the tutorial:

var instructorEvent = Coursetro.Instructor();
instructorEvent.watch(function(error, result){
            if (!error)
                {
                    $("#loader").hide();
                    $("#instructor").html(result.args.name + ' (' + result.args.age + ' years old)');
                } else {
                    $("#loader").hide();
                    console.log(error);
                }
        });

How to listen permanently to events in a smart contract from node.js Application?

1 Answers