Web3.js 1.0 – Listening to Events

eventsweb3js

I have a problem when listening for events from my contract.

Code js :

var Web3 = require('web3');
var abi = '...';
var contractAddress = '0x62e7Dd1Af52d5A08D401b1e156cC4CB1d2f89d57';
var eventName = 'Transfer';
//var web3;
var etat;
const web3 = new Web3(new Web3.providers.WebsocketProvider('http://127.0.0.1:8545'));
/*
var MyContract = new web3.eth.Contract(JSON.parse(abi));
var myContractInstance = MyContract.at('0x78e97bcc5b5dd9ed228fed7a4887c0d7287344a9');

// watch for an event with {some: 'args'}
var myEvent = myContractInstance.Transfer({}, {fromBlock: 0, toBlock: 'latest'});
myEvent.watch(function(error, result){
    console.log(result)
});

// would get all past logs again.
var myResults = myEvent.get(function(error, logs){ console.log(logs) });



// would stop and uninstall the filter
myEvent.stopWatching();
*/



var TokenContract = new web3.eth.Contract(JSON.parse(abi),contractAddress);
TokenContract.events.allEvents({ fromBlock: 'latest' }, console.log)
console.log('1********************************************************************************')
console.log(TokenContract);
console.log('2********************************************************************************')
var event = TokenContract.events.Transfer();
console.log(event);
console.log('3********************************************************************************')

TokenContract.once('Transfer', {
}, function(error, event){ console.log(event); });

event.watch(function(error, result){
    if (!error) {
        alert("wait for a while, check for block Synchronization or block creation");
        console.log(result);
        console.log('pas d erreur');
    }else {
        console.log(error);
        console.log('erreur')
    }
});

I have tested a lot of possibilities but the function .watch doesn't run :

TypeError: event.watch is not a function

How do you listen to events using Web3 1.0?

Best Answer

event.watch is not a function in web3.0 v1.0

Use the snippet below instead, but remember that:

  • myContract should be a variable you assigned which is an instance of your contract
  • MyEvent should be replaced with the actual name of your event.
myContract.events.MyEvent({
    filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // Using an array means OR: e.g. 20 or 23
    fromBlock: 0
}, function(error, event){ console.log(event); })
.on('data', function(event){
    console.log(event); // same results as the optional callback above
})
.on('changed', function(event){
    // remove event from local database
})
.on('error', console.error);

Also see the docs here.

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