[Ethereum] How to decode input data with ABI using golang

golang

There is a tool on npm ethereum-input-data-decoder. And yes, i can read input data as hex.

And i hope that i can decode transaction's inputdata using golang.
For example 0xa9059cbb00000000000000000000000067f883a42031215622e0b84c96d0e4dca7a3ce810000000000000000000000000000000000000000000000000000000005f5e100

thx.

Best Answer

took me a bit of time to figure out that myAbi.Unpack(...) unpacks output of a method or event. In your case (and mine) we want to unpack the inputs. Here is a working code sample

// example of transaction input data
txInput := "0xa5142faa00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000003"

// load contract ABI
abi, err := abi.JSON(strings.NewReader(myContractAbi))
if err != nil {
    log.Fatal(err)
}

// decode txInput method signature
decodedSig, err := hex.DecodeString(txInput[2:10])
if err != nil {
    log.Fatal(err)
}

// recover Method from signature and ABI
method, err := abi.MethodById(decodedSig)
if err != nil {
    log.Fatal(err)
}

// decode txInput Payload
decodedData, err := hex.DecodeString(txInput[10:])
if err != nil {
    log.Fatal(err)
}

// create strut that matches input names to unpack
// for example my function takes 2 inputs, with names "Name1" and "Name2" and of type uint256 (solidity)
type FunctionInputs struct {
    Name1 *big.Int // *big.Int for uint256 for example
    Name2 *big.Int
}

var data FunctionInputs

// unpack method inputs
err = method.Inputs.Unpack(&data, decodedData)
if err != nil {
    log.Fatal(err)
}

fmt.Println(data)
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