Generate golang binding code for smart contracts written in solidity

Introduction

If you use golang to connect to Ethereum, it's easy to generate binding code that runs Ethereum smart contracts directly from golang. From two years ago to last year, I implemented this method when I created an escrow service using Ethereum's smart contract.

let's try it

Required software

A smart contract that generates binding code

Solidity source code for standard ERC20 smart contracts.

Erc20.sol

pragma solidity ^0.4.24;

contract ERC20 {
    string public constant name = "";
    string public constant symbol = "";
    uint8 public constant decimals = 0;

    function totalSupply() public constant returns (uint);
    function balanceOf(address tokenOwner) public constant returns (uint balance);
    function allowance(address tokenOwner, address spender) public constant returns (uint remaining);
    function transfer(address to, uint tokens) public returns (bool success);
    function approve(address spender, uint tokens) public returns (bool success);
    function transferFrom(address from, address to, uint tokens) public returns (bool success);

    event Transfer(address indexed from, address indexed to, uint tokens);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}

Binding code generation

Once you generate an abi from solidity and a golang binding from abi.

solidity -> abi (Erc20_sol_ERC20.Generate abi)
$ solcjs --abi Erc20.sol

abi ->golang binding(Erc20.Generate go)
$ abigen --abi Erc20_sol_ERC20.abi -pkg contract -out Erc20.go

Generated method

A method is generated in Erc20.go following the interface of solidity.

func (_Erc20 *Erc20Raw) Call(opts *bind.CallOpts, result interface{}, method string, params ...interface{}) error {
func (_Erc20 *Erc20Raw) Transfer(opts *bind.TransactOpts) (*types.Transaction, error) {
func (_Erc20 *Erc20Raw) Transact(opts *bind.TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
func (_Erc20 *Erc20CallerRaw) Call(opts *bind.CallOpts, result interface{}, method string, params ...interface{}) error {
func (_Erc20 *Erc20TransactorRaw) Transfer(opts *bind.TransactOpts) (*types.Transaction, error) {
func (_Erc20 *Erc20TransactorRaw) Transact(opts *bind.TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
func (_Erc20 *Erc20Caller) Allowance(opts *bind.CallOpts, tokenOwner common.Address, spender common.Address) (*big.Int, error) {
func (_Erc20 *Erc20Session) Allowance(tokenOwner common.Address, spender common.Address) (*big.Int, error) {
func (_Erc20 *Erc20CallerSession) Allowance(tokenOwner common.Address, spender common.Address) (*big.Int, error) {
func (_Erc20 *Erc20Caller) BalanceOf(opts *bind.CallOpts, tokenOwner common.Address) (*big.Int, error) {
func (_Erc20 *Erc20Session) BalanceOf(tokenOwner common.Address) (*big.Int, error) {
func (_Erc20 *Erc20CallerSession) BalanceOf(tokenOwner common.Address) (*big.Int, error) {
func (_Erc20 *Erc20Caller) Decimals(opts *bind.CallOpts) (uint8, error) {
func (_Erc20 *Erc20Session) Decimals() (uint8, error) {
func (_Erc20 *Erc20CallerSession) Decimals() (uint8, error) {
func (_Erc20 *Erc20Caller) Name(opts *bind.CallOpts) (string, error) {
func (_Erc20 *Erc20Session) Name() (string, error) {
func (_Erc20 *Erc20CallerSession) Name() (string, error) {
func (_Erc20 *Erc20Caller) Symbol(opts *bind.CallOpts) (string, error) {
func (_Erc20 *Erc20Session) Symbol() (string, error) {
func (_Erc20 *Erc20CallerSession) Symbol() (string, error) {
func (_Erc20 *Erc20Caller) TotalSupply(opts *bind.CallOpts) (*big.Int, error) {
func (_Erc20 *Erc20Session) TotalSupply() (*big.Int, error) {
func (_Erc20 *Erc20CallerSession) TotalSupply() (*big.Int, error) {
func (_Erc20 *Erc20Transactor) Approve(opts *bind.TransactOpts, spender common.Address, tokens *big.Int) (*types.Transaction, error) {
func (_Erc20 *Erc20Session) Approve(spender common.Address, tokens *big.Int) (*types.Transaction, error) {
func (_Erc20 *Erc20TransactorSession) Approve(spender common.Address, tokens *big.Int) (*types.Transaction, error) {
func (_Erc20 *Erc20Transactor) Transfer(opts *bind.TransactOpts, to common.Address, tokens *big.Int) (*types.Transaction, error) {
func (_Erc20 *Erc20Session) Transfer(to common.Address, tokens *big.Int) (*types.Transaction, error) {
func (_Erc20 *Erc20TransactorSession) Transfer(to common.Address, tokens *big.Int) (*types.Transaction, error) {
func (_Erc20 *Erc20Transactor) TransferFrom(opts *bind.TransactOpts, from common.Address, to common.Address, tokens *big.Int) (*types.Transaction, error) {
func (_Erc20 *Erc20Session) TransferFrom(from common.Address, to common.Address, tokens *big.Int) (*types.Transaction, error) {
func (_Erc20 *Erc20TransactorSession) TransferFrom(from common.Address, to common.Address, tokens *big.Int) (*types.Transaction, error) {
func (it *Erc20ApprovalIterator) Next() bool {
func (it *Erc20ApprovalIterator) Error() error {
func (it *Erc20ApprovalIterator) Close() error {
func (_Erc20 *Erc20Filterer) FilterApproval(opts *bind.FilterOpts, tokenOwner []common.Address, spender []common.Address) (*Erc20ApprovalIterator, error) {
func (_Erc20 *Erc20Filterer) WatchApproval(opts *bind.WatchOpts, sink chan<- *Erc20Approval, tokenOwner []common.Address, spender []common.Address) (event.Subscription, error) {
func (it *Erc20TransferIterator) Next() bool {
func (it *Erc20TransferIterator) Error() error {
func (it *Erc20TransferIterator) Close() error {
func (_Erc20 *Erc20Filterer) FilterTransfer(opts *bind.FilterOpts, from []common.Address, to []common.Address) (*Erc20TransferIterator, error) {
func (_Erc20 *Erc20Filterer) WatchTransfer(opts *bind.WatchOpts, sink chan<- *Erc20Transfer, from []common.Address, to []common.Address) (event.Subscription, error) {

ERC20 BalanceOf () execution example from golang

Now you can easily execute smart contracts from golang.

client, _ := ethclient.Dial("Ethereum connection URL(infura.io etc.)")
erc20, _ := contract.NewErc20("Contract address(type:common.Address)", client)
balance, _ := erc20.BalanceOf(&bind.CallOpts{}, "Address where you want to check your balance(type:common.Address)")