Finding ETH erc20 tokens balance using golang and infura.io

erc20_balance.go

/// Import on the top of your project
import "github.com/ethereum/go-ethereum/crypto"

type ethHandlerResult struct {
	Result string `json:"result"`
	Error  struct {
		Code    int64  `json:"code"`
		Message string `json:"message"`
	} `json:"error"`
}
address := "0x757d576da3fba018b1bd9cdd05fa4ca0261792c8" // Account Address here
contractAddress := "0xdac17f958d2ee523a2206206994597c13d831ec7" // Contract address, for example, it's tether
infuraProjectID := "Write your infura project ID here" // https://infura.io
data := crypto.Keccak256Hash([]byte("balanceOf(address)")).String()[0:10] + "000000000000000000000000" + address[2:]
postBody, _ = json.Marshal(map[string]interface{}{
	"id":      1,
	"jsonrpc": "2.0",
	"method":  "eth_call",
	"params": []interface{}{
		map[string]string{
			"to":   contractAddress,
			"data": data,
		},
		"latest",
	},
})
requestBody := bytes.NewBuffer(postBody)
resp, err := http.Post("https://mainnet.infura.io/v3/" + infuraProjectID, "application/json", requestBody)
if err != nil {
	return nil, err
}

ethResult := new(ethHandlerResult)
if err := json.NewDecoder(resp.Body).Decode(&ethResult); err != nil {
	return nil, err
}
balance.SetString(ethResult.Result[2:], 16)
fmt.Println(balance)

Where is ethResult used on line 33 declared?

@dimalinux Thanks for your catch, that should be a variable of type ethHandlerResult, I updated the gist.