abi.mdx

Application Binary interface

To use the library import:

"github.com/umbracle/ethgo/abi"

Declare basic objects:

typ, err := abi.NewType("uint256")

or

typ = abi.MustNewType("uint256")

and use it to encode/decode the data:

num := big.NewInt(1)

encoded, err := typ.Encode(num)
if err != nil {
    panic(err)
}

decoded, err := typ.Decode(encoded) // decoded as interface
if err != nil {
    panic(err)
}

num2 := decoded.(*big.Int)
fmt.Println(num.Cmp(num2) == 0) // num == num2

You can also codify structs as Solidity tuples:

import (
	"fmt"
    
	"github.com/umbracle/ethgo"
	"github.com/umbracle/ethgo/abi"
	"math/big"
)

func main() {
	typ := abi.MustNewType("tuple(address a, uint256 b)")

	type Obj struct {
		A ethgo.Address
		B *big.Int
	}
	obj := &Obj{
		A: ethgo.Address{0x1},
		B: big.NewInt(1),
	}

	// Encode
	encoded, err := typ.Encode(obj)
	if err != nil {
		panic(err)
	}

	// Decode output into a map
	res, err := typ.Decode(encoded)
	if err != nil {
		panic(err)
	}

	// Decode into a struct
	var obj2 Obj
	if err := typ.DecodeStruct(encoded, &obj2); err != nil {
		panic(err)
	}

	fmt.Println(res)
	fmt.Println(obj)
}

Testing

The ABI codifier uses randomized tests with e2e integration tests with a real Geth client to ensure that the codification is correct and provides the same results as the AbiEncoder from Solidity.