Updated Go file for transferring tokens in goethereumbook

transfer_tokens.go

package main

import (
	"context"
	"fmt"
	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethclient"
	"github.com/metachris/eth-go-bindings/erc20"
	"io/ioutil"
	"log"
	"math/big"
	"strings"
)

func main() {
  client, err := ethclient.Dial("https://rinkeby.infura.io/v3/{{API_KEY}}") // API KEY needed from infura
	if err != nil {
		log.Fatal(err)
	}
	address := common.HexToAddress("0x0000000000000000000000000000000000000000") // contract of token, e.g. https://rinkeby.etherscan.io/address/0x014dF965e86d241b7CB1303C235CBDB197cf3e2e
	token, err := erc20.NewErc20(address, client) // see metachris/eth-go-bindings for go bindings
	if err != nil {
		log.Fatal(err)
	}
	name, err := token.Name(nil)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println("Name of token:", name) // optional
  key, err := ioutil.ReadFile("./keystores/{{KEYSTORE_FILE}}") // keystore of wallet that holds ERC-20 tokens
	chainId, err := client.NetworkID(context.Background())
	if err != nil {
		log.Fatal(err)
	}
	auth, err := bind.NewTransactorWithChainID(strings.NewReader(string(key)), "PASSWORD", chainId)
	if err != nil {
		log.Fatal(err)
	}
  value := big.NewInt(10000000000000000000) // 10 of given token
	tx, err := token.Transfer(auth, common.HexToAddress("0x0000000000000000000000000000000000000000"), value) // recipient address
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("transfer pending: 0x%x\n", tx.Hash())
}