returnValues parsed incorrectly

[yuwiggin]

Description

The value was wrong in a String field of the returnValues.

Expected behavior

Calling contract.events.Authorized({ fromBlock: 8806769 }, function(error, event) { console.log(event); })
should return

......
"returnValues":{"0":"GeekGit",......,"name":"GeekGit",......}
......

Actual behavior

But returned

......
"returnValues":{"0":"0xef563641eef48cfa4dddd5f98049665d481ac4507793218a74d393e836c49d67",......,"name":"0xef563641eef48cfa4dddd5f98049665d481ac4507793218a74d393e836c49d67",......}
......

Steps to reproduce the behavior

1. Import `web3`
2. Set the provider to `WebsocketProvider`, i.e. infura
3. Fetch the block

contract.events.Authorized({ fromBlock: 8806769 }, function(error, event) {
   console.log(event);
});   

ABI JSON

      "events": {   "0x6f7089ad02947bd25268f2724218c84efd1ec156c5ad2d3366599cae89ff71f9": {
          "anonymous": false,
          "inputs": [
            {
              "indexed": true,
              "internalType": "string",
              "name": "name",
              "type": "string"
            },
            {
              "indexed": true,
              "internalType": "address",
              "name": "owner",
              "type": "address"
            },
            {
              "indexed": false,
              "internalType": "address",
              "name": "from",
              "type": "address"
            }
          ],
          "name": "Authorized",
          "type": "event",
          "signature": "0x6f7089ad02947bd25268f2724218c84efd1ec156c5ad2d3366599cae89ff71f9"
        }

Versions

• web3.js: 1.2.1
• nodejs: v8.15.1
• NPM: 6.9.2

[cgewecke]

Hi @yuwiggin

Your string event argument is indexed, so the output looks like it might be correct?

From the events section of the solidity docs

You can add the attribute indexed to up to three parameters which adds them to a special data structure known as “topics” instead of the data part of the log. If you use arrays (including string and bytes) as indexed arguments, its Keccak-256 hash is stored as a topic instead, this is because a topic can only hold a single word (32 bytes).

[yuwiggin]

Thanks @cgewecke . So, it can't be fetched in any way?

[cgewecke]

@yuwiggin The fired event will contain the keccak256 hash, so if you know what the string is in advance, you can always synthesize it using web3.utils.keccak256(val) and compare the emitted value with a pre-computed hash.

But often strings are being used for arbitrary, user-generated values...

Incidentally, it's not possible to set an event filter for an indexed string by the computed hash either - you have to do that manually in the event handler if it's helpful for your use case.

[nivida]

@cgewecke I will back-port this PR to the 1.x branch #3061

[cgewecke]

Closing in favor #344