Example of how to decode input data in transaction

[lmittmann]

Example of how to decode input data in transaction

[lmittmann]

Lets say you have a ERC20 transfer tx. You need to define the tokens method first and then you can use it to decode the input data like this:

funcTransfer := w3.MustNewFunc("transfer(address to, uint256 value)", "bool")
input := w3.B("0xa9059cbb00000000000000000000000005972A481E2DdB2d332fDd88A10665D8e9417c20000000000000000000000000000000000000000000000000000000000000ffff")
	
var (
	to    common.Address
	value *big.Int
)
err := funcTransfer.DecodeArgs(input, &to, &value)
if err != nil {
	// ...
}
fmt.Printf("to: %s, amount: %v\n", to, value)

The input is just some random transfer calldata. You can also take it from a tx you fetched before.

[vodves-vodves]

thanks sir)

[vodves-vodves]

Can I ask you one more question? How do I take only transfer transactions? Because it can also decode approve transactions

[lmittmann]

If you already have a list of transactions you can filter by the function selector (the first 4 byte of the input data). The function selector of the transfer method is here: funcTransfer.Selector.

Otherwise it might be better to look for Transfer events instead.

evtTransfer := w3.MustNewEvent("Transfer(address indexed from, address indexed to, uint256 value)")
client := w3.MustDial("https://rpc.ankr.com/eth")

var logs []types.Log
err = client.Call(
	eth.Logs(ethereum.FilterQuery{
		Topics:    [][]common.Hash{{evtTransfer.Topic0}},
		FromBlock: big.NewInt(17_000_000),
		ToBlock:   big.NewInt(17_000_100),
	}).Returns(&logs),
)
if err != nil {
	// ...
}

for _, log := range logs {
	var (
		from  common.Address
		to    common.Address
		value *big.Int
	)
	err := evtTransfer.DecodeArgs(&log, &from, &to, &value)
	if err != nil {
		// ...
	}
	fmt.Printf("from: %s, to: %s, amount: %v\n", from, to, value)
}

You can also filter the logs for a specific token only.