README.md

description
Tutorial on how to load an initialize a smart contract with Go.

Loading a Smart Contract

These section requires knowledge of how to compile a smart contract's ABI to a Go contract file. If you haven't already gone through it, please read the section first.

Once you've compiled your smart contract's ABI to a Go package using the abigen tool, the next step is to call the "New" method, which is in the format New<ContractName>, so in our example if you recall it's going to be NewStore. This initializer method takes in the address of the smart contract and returns a contract instance that you can start interact with it.

address := common.HexToAddress("0x147B8eb97fD247D06C4006D269c90C1908Fb5D54")
instance, err := store.NewStore(address, client)
if err != nil {
  log.Fatal(err)
}

_ = instance // we'll be using this in the next section

---

Full code

Commands

solc --abi Store.sol
solc --bin Store.sol
abigen --bin=Store_sol_Store.bin --abi=Store_sol_Store.abi --pkg=store --out=Store.go

Store.sol

pragma solidity ^0.4.24;

contract Store {
  event ItemSet(bytes32 key, bytes32 value);

  string public version;
  mapping (bytes32 => bytes32) public items;

  constructor(string _version) public {
    version = _version;
  }

  function setItem(bytes32 key, bytes32 value) external {
    items[key] = value;
    emit ItemSet(key, value);
  }
}

contract_load.go

package main

import (
	"fmt"
	"log"

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

	store "./contracts" // for demo
)

func main() {
	client, err := ethclient.Dial("https://rinkeby.infura.io")
	if err != nil {
		log.Fatal(err)
	}

	address := common.HexToAddress("0x147B8eb97fD247D06C4006D269c90C1908Fb5D54")
	instance, err := store.NewStore(address, client)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("contract is loaded")
	_ = instance
}

solc version used for these examples

$ solc --version
0.4.24+commit.e67f0147.Emscripten.clang