How to parse event in transaction log with Anchor

Question

I have following transaction logs which contains triggered event and I want to parse it:

'Program log: Instruction: Init',
'Program data: 867fyqeFJJGYZDSk+Vy/7Cpm35d+fps/e3WovaZGp4v+BTlIzV0qngEAAGXNHQAAAAA=',
'Program CBVe4r7UuJtMiBtTUXH8ic7dxqSvNcUWBNX25c2dVAYg consumed 6522 of 571982 compute units',
'Program CBVe4r7UuJtMiBtTUXH8ic7dxqSvNcUWBNX25c2dVAYg success'

This is as far as I get get with parsing:

const tx = await anchor.getProvider().connection.getTransaction(signature, {
            commitment: "confirmed",
        });

const log = tx.meta.logMessages[1];
const message = log.substring(log.indexOf(':')+1);
consle.log(message);

Notes:

• Event Logs are generated with emit! (which use msq! under hood and it's just a convenience macro for converting an arbitrary struct to a string).

Answer 1

After some digging to Anchor documentation I found the EventParser which is exactly what I wanted.

import * as anchor from "@project-serum/anchor";
import {BorshCoder, EventParser, Program, web3} from "@project-serum/anchor";
import {Tcf} from "../target/types/tcf";


anchor.setProvider(anchor.AnchorProvider.env());
const program = anchor.workspace.CoinFlip as Program<Tcf>;

// Get transaction from its signature
const tx = await anchor.getProvider().connection.getTransaction(signature, {
     commitment: "confirmed",
});

const eventParser = new EventParser(program.programId, new BorshCoder(program.idl));
const events = eventParser.parseLogs(tx.meta.logMessages);
for (let event of events) {
    console.log(event);
}

Answer 2

I was struggling with the accepted answer to parse Jupiter perp log events, then dug into how they parse logs: https://github.com/jup-ag/instruction-parser/blob/main/src/lib/get-events.ts

I am not very familiar with solana ecosystem, this might be an alternative way of storing logs by passing it as instruction (?)

Copying the parsing code here in case they make repo private:

    import { Event, Program, utils } from "@coral-xyz/anchor";
    import { JUPITER_V6_PROGRAM_ID } from "../constants";
    import { TransactionWithMeta } from "../types";

    export function getEvents(
      program: Program,
      transactionResponse: TransactionWithMeta
    ) {
      let events: Event[] = [];

      if (transactionResponse && transactionResponse.meta) {
        let { meta } = transactionResponse;

        meta.innerInstructions?.map(async (ix) => {
          ix.instructions.map(async (iix) => {
            if (!iix.programId.equals(JUPITER_V6_PROGRAM_ID)) return;
            if (!("data" in iix)) return; // Guard in case it is a parsed decoded instruction

            const ixData = utils.bytes.bs58.decode(iix.data);
            const eventData = utils.bytes.base64.encode(ixData.subarray(8));
            const event = program.coder.events.decode(eventData);

            if (!event) return;

            events.push(event);
          });
        });
      }

      return events;
    }