read contract event with go ethereum

go-ethereum-read-event.go

package main

import (
	"context"
	"fmt"
	"github.com/ethereum/go-ethereum"
	"github.com/ethereum/go-ethereum/accounts/abi"
	"github.com/ethereum/go-ethereum/common"
	"log"
	"math/big"
	"strings"

	"github.com/ethereum/go-ethereum/ethclient"
)

const rawABI = `
[
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": true,
          "internalType": "address",
          "name": "from",
          "type": "address"
        },
        {
          "indexed": false,
          "internalType": "uint256",
          "name": "amount",
          "type": "uint256"
        }
      ],
      "name": "FallbackEvent",
      "type": "event"
    },
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": true,
          "internalType": "address",
          "name": "previousOwner",
          "type": "address"
        },
        {
          "indexed": true,
          "internalType": "address",
          "name": "newOwner",
          "type": "address"
        }
      ],
      "name": "OwnershipTransferred",
      "type": "event"
    },
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": true,
          "internalType": "address",
          "name": "from",
          "type": "address"
        },
        {
          "indexed": false,
          "internalType": "uint256",
          "name": "amount",
          "type": "uint256"
        }
      ],
      "name": "ReceiveEvent",
      "type": "event"
    },
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": true,
          "internalType": "address",
          "name": "receiver",
          "type": "address"
        },
        {
          "indexed": false,
          "internalType": "uint256",
          "name": "amount",
          "type": "uint256"
        }
      ],
      "name": "WithDrawEvent",
      "type": "event"
    },
    {
      "stateMutability": "payable",
      "type": "fallback"
    },
    {
      "inputs": [],
      "name": "destory",
      "outputs": [],
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "inputs": [],
      "name": "getBalance",
      "outputs": [
        {
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
        }
      ],
      "stateMutability": "view",
      "type": "function"
    },
    {
      "inputs": [],
      "name": "owner",
      "outputs": [
        {
          "internalType": "address",
          "name": "",
          "type": "address"
        }
      ],
      "stateMutability": "view",
      "type": "function"
    },
    {
      "inputs": [],
      "name": "renounceOwnership",
      "outputs": [],
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "inputs": [
        {
          "internalType": "address",
          "name": "newOwner",
          "type": "address"
        }
      ],
      "name": "transferOwnership",
      "outputs": [],
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "inputs": [
        {
          "internalType": "address payable",
          "name": "receiver",
          "type": "address"
        },
        {
          "internalType": "uint256",
          "name": "amount",
          "type": "uint256"
        }
      ],
      "name": "withDraw",
      "outputs": [],
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "stateMutability": "payable",
      "type": "receive"
    }
  ]
`

const ropstenHttpsEndpoint = "https://ropsten.infura.io/v3/77a8f7b1379d440b8c06e82f37d05657"
const ropstenFaucetContractAddress = "0xf1EEfEE62A8651c3772cd8D7ba9031b7029316f7"
const blockNumber = 12218203

func main() {
	contractAbi, err := abi.JSON(strings.NewReader(rawABI))
	if err != nil {
		log.Fatal(err)
	}
	// get abi events info
	for _, event := range contractAbi.Events {
		fmt.Printf("Event Name: %s\n", event.Name)
		fmt.Printf("Event ID: %s\n", event.ID)
		fmt.Printf("Event RawName: %s\n", event.RawName)
		fmt.Printf("Event Sig: %s\n", event.Sig)
		for index, input := range event.Inputs {
			fmt.Printf("input %d, Name: %s, Type:%s, indexed: %t\n", index, input.Name, input.Type, input.Indexed)
		}
	}

	client, err := ethclient.Dial(ropstenHttpsEndpoint)
	if err != nil {
		log.Fatal(err)
	}

	contractAddress := common.HexToAddress(ropstenFaucetContractAddress)
	blockLimit := big.NewInt(blockNumber)
	query := ethereum.FilterQuery{
		FromBlock: blockLimit,
		ToBlock:   blockLimit,
		Addresses: []common.Address{contractAddress},
	}
	// query contract event in block 12218203
	logs, err := client.FilterLogs(context.Background(), query)
	if err != nil {
		log.Fatal(err)
	}

	// parse logs
	for _, vLog := range logs {
		fmt.Printf("Log Block Number: %d\n", vLog.BlockNumber)
		fmt.Printf("TxHash: %s\n", vLog.TxHash)
		fmt.Printf("Topics[0]: %s\n", vLog.Topics[0].Hex())
		//  Topic[0] is the event signature hash value
		//  equals to
		//	logWithDrawEventSig := []byte("WithDrawEvent(address,uint256)")
		//	logWithDrawEventSigHash := crypto.Keccak256Hash(logWithDrawEventSig)
		switch vLog.Topics[0] {
		case contractAbi.Events["WithDrawEvent"].ID:
			fmt.Printf("Log Name: WithDrawEvent\n")
			// 解析所有Topic的信息
			for index := range vLog.Topics {
				fmt.Printf("topic %d: %s\n", index, vLog.Topics[index].Hex())
			}
			
			// ====================================
			// decode event log data
			// ====================================

			// method 1:
			data, errUnpack := contractAbi.Unpack("WithDrawEvent", vLog.Data)
			if errUnpack != nil {
				log.Fatal(errUnpack)
			}
			fmt.Printf("data: %s\n", data)

			// method 2: decode to map
			dataMap := make(map[string]interface{})
			err = contractAbi.UnpackIntoMap(dataMap, "WithDrawEvent", vLog.Data)
			if err != nil {
				log.Fatal(err)
			}
			fmt.Printf("dataMap: %v\n", dataMap)

			// method 3: decode by event inputs
			inputs, unpackValuesErr := contractAbi.Events["WithDrawEvent"].Inputs.UnpackValues(vLog.Data)
			if unpackValuesErr != nil {
				log.Fatal(unpackValuesErr)
			}
			fmt.Printf("inputs: %v\n", inputs)

			// method 4: decode by event inputs into map
			inputsMap := make(map[string]interface{})
			err := contractAbi.Events["WithDrawEvent"].Inputs.UnpackIntoMap(inputsMap, vLog.Data)
			if err != nil {
				log.Fatal(err)
			}
			fmt.Printf("inputsMap: %v\n", inputsMap)

		}

		fmt.Printf("\n\n")
	}

}

go.mod

module ReadContractEvent

go 1.18

require github.com/ethereum/go-ethereum v1.10.17

require (
	github.com/StackExchange/wmi v0.0.0-20180116203802-5d049714c4a6 // indirect
	github.com/btcsuite/btcd/btcec/v2 v2.1.2 // indirect
	github.com/deckarep/golang-set v1.8.0 // indirect
	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1 // indirect
	github.com/go-ole/go-ole v1.2.1 // indirect
	github.com/go-stack/stack v1.8.0 // indirect
	github.com/gorilla/websocket v1.4.2 // indirect
	github.com/shirou/gopsutil v3.21.4-0.20210419000835-c7a38de76ee5+incompatible // indirect
	github.com/tklauser/go-sysconf v0.3.5 // indirect
	github.com/tklauser/numcpus v0.2.2 // indirect
	golang.org/x/crypto v0.0.0-20210322153248-0c34fe9e7dc2 // indirect
	golang.org/x/sys v0.0.0-20210816183151-1e6c022a8912 // indirect
	gopkg.in/natefinch/npipe.v2 v2.0.0-20160621034901-c1b8fa8bdcce // indirect
)

This is how to parse contract log event info with the latest go-ethereum(v1.10.17).
The contract is deploy by on ropsten faucet website and the query log event is under https://ropsten.etherscan.io/tx/0x488561fb7a18bdc4627f6be2bbf3b660520ace7a5dad1de5ef1b693c6eeaf168#eventlog

Here is the output

Event Name: FallbackEvent
Event ID: 0x26875833861a2b006512a11f1b86edf95df96131040f3caeed72989ee9858083
Event RawName: FallbackEvent
Event Sig: FallbackEvent(address,uint256)
input 0, Name: from, Type:address, indexed: true
input 1, Name: amount, Type:uint256, indexed: false
Event Name: OwnershipTransferred
Event ID: 0x8be0079c531659141344cd1fd0a4f28419497f9722a3daafe3b4186f6b6457e0
Event RawName: OwnershipTransferred
Event Sig: OwnershipTransferred(address,address)
input 0, Name: previousOwner, Type:address, indexed: true
input 1, Name: newOwner, Type:address, indexed: true
Event Name: ReceiveEvent
Event ID: 0xcc85d09d309785db93d6df19917f2e6cc07fe27cd01c08c8279145deb5cf4526
Event RawName: ReceiveEvent
Event Sig: ReceiveEvent(address,uint256)
input 0, Name: from, Type:address, indexed: true
input 1, Name: amount, Type:uint256, indexed: false
Event Name: WithDrawEvent
Event ID: 0x95f64928a3a24eaef05a724d2235d5a7bd84368972737e2596b1110e117dfc65
Event RawName: WithDrawEvent
Event Sig: WithDrawEvent(address,uint256)
input 0, Name: receiver, Type:address, indexed: true
input 1, Name: amount, Type:uint256, indexed: false
Log Block Number: 12218203
TxHash: 0x488561fb7a18bdc4627f6be2bbf3b660520ace7a5dad1de5ef1b693c6eeaf168
Topics[0]: 0x95f64928a3a24eaef05a724d2235d5a7bd84368972737e2596b1110e117dfc65
Log Name: WithDrawEvent
topic 0: 0x95f64928a3a24eaef05a724d2235d5a7bd84368972737e2596b1110e117dfc65
topic 1: 0x000000000000000000000000f39fd6e51aad88f6f4ce6ab8827279cfffb92266
data: [100000000000000000]
dataMap: map[amount:100000000000000000]
inputs: [100000000000000000]
inputsMap: map[amount:100000000000000000]