filter indexed events from browser using web3.js

Question

I Have a contract defined which logs 2 events :

 myEvent(string data, uint32 indexed id),
 myEvent1(string data, uint32 indexed id). 

I want to filter all the events on the browser using web3 by passing the indexed id.

1. How to get all the events with the passed id.

2. when I try to get the event from the txHash it returns the event data but only string paramater is decode correctly. the uint32 type is returned as a Big number. How do is resolve their two issues??

Answer 1

Here I am listing an example how I have applied event filter

In this example I have used the candidate name as a filter parameter. Secondly it is looking from block 0 to latest.

Hope this helps.

Event Declaration - Solidity Contract

event RegisterCandidate(uint256 indexed
eventTimeStamp, address indexed _from, bytes32 indexed _candidateName);

Code in Java Script

var event = contractInstance.RegisterCandidate( {_candidateName: "Abc"}, {fromBlock: 0, toBlock: 'latest'});

    event.watch(function(error, response)
    {
       //once the event has been detected, take actions as desired
        var data = 'from: ' + response.args._from+"<br>candidateName: "+web3.toUtf8(response.args._candidateName) +"<br>";
    });

Answer 2

In your specific case that would be:

var myEvent = contract.myEvent({id: 1});

myEvent.watch((error, result) => {

    var data = result["args"]["data"];
    var id = result["args"]["id"]; // always 1
    // Do Something 
});

Which would watch only events with id = 1.

Answer 3

How to get all the events with the passed id.

As indicated by @cees-van-wijk, this fetches every new event:

var myEvent = contract.myEvent({id: 1});
myEvent.watch((error, result) => {
    var data = result["args"]["data"];
    var id = result["args"]["id"]; // always 1
    // Do Something 
});

this fetches all previous events

myEvent.get((error, result) => {
    var data = result["args"]["data"];
    var id = result["args"]["id"]; // always 1
    // Do Something 
});`

when I try to get the event from the txHash it returns the event data but only string paramater is decode correctly. the uint32 type is returned as a Big number. How do is resolve their two issues??

You can easily decode most uint type using Number(uint)