2

As an example, getPastLogs defines topics parameter as:

topics - Array: An array of values which must each appear in the log entries. The order is important, if you want to leave topics out use null, e.g. [null, '0x12...']. You can also pass an array for each topic with options for that topic e.g. [null, ['option1', 'option2']]

If I mean reading this right, then:

  • ['0x12...'] will filter by 0x12... topic.
  • [null, '0x12...'] will match all topics, and filter by index parameters.

I don't comprehend the [null, ['option1', 'option2']] example though.

Currently, I am doing it as such:

const [syncLogs, swapLogs] = await Promise.all([
  web3.eth.getPastLogs({
    fromBlock: firstBlockNumber,
    toBlock: firstBlockNumber,
    topics: [
      syncToken.signature,
    ],
  }),
  web3.eth.getPastLogs({
    fromBlock: firstBlockNumber,
    toBlock: firstBlockNumber,
    topics: [
      swapToken.signature,
    ],
  }),
]);

Though this results in two distinct JSON-RPC calls.

Is there a way to filter by multiple topics?

1 Answer 1

5

[null, ['option1', 'option2']] means the first topic can be anything, the second topic has to be either 'option1' or 'option2'.

5
  • I am asking if there is a way to filter all logs by multiple first topics.
    – Gajus
    Commented Jun 4, 2021 at 15:21
  • @Gajus Did you try something like [['topic1','topic2']]? In general topics are good enough for simple queries, for more complex you should use an indexer or something more advanced like graphql.
    – Ismael
    Commented Jun 4, 2021 at 15:47
  • I am basically interested in all Sync and Swap events. The approach that I've shared in the original post works, I was simply wondering if I could pull the same data using a single call.
    – Gajus
    Commented Jun 4, 2021 at 16:53
  • 2
    @Gajus Can you try something like topics: [ [syncToken.signature, swapToken.signature] ],? The system underneath uses bloom filters for topics, it has some use cases, but it has its own limitations.
    – Ismael
    Commented Jun 4, 2021 at 17:29
  • Your last suggestion does indeed what I was looking for. Thank you!
    – Gajus
    Commented Jun 5, 2021 at 16:43

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