feat(add load balance logic): add load balance logic

add load balance logic

Author: yuanyu90221

README.md

@@ -57,4 +57,23 @@ ganache-cli
 
 ```yaml
 ETH_JSON_RPC_URL=http://localhost:8545
+```
+
+## add lookup balance logic
+
+```golang
+// find specific address balance
+	addr := config.AppConfig.EthAddress
+	address := common.HexToAddress(addr)
+
+	balance, err := client.BalanceAt(context.Background(), address, nil)
+	if err != nil {
+		log.Fatalf("Error to get the balance:%v", err)
+	}
+	fmt.Println("The balance:", balance)
+	// 1 ether = 10^18 wei
+	fBalance := new(big.Float)
+	fBalance.SetString(balance.String())
+	balanceEther := new(big.Float).Quo(fBalance, big.NewFloat(math.Pow10(18)))
+	fmt.Println("address:", config.AppConfig.EthAddress, "has", balanceEther, "ether")
 ```

internal/config/config.go

@@ -8,6 +8,7 @@ import (
 
 type Config struct {
 	EthJsonRpcURL string `mapstructure:"ETH_JSON_RPC_URL"`
+	EthAddress    string `mapstructure:"ETH_ADDRESS"`
 }
 
 var AppConfig *Config
@@ -19,6 +20,7 @@ func init() {
 	v.SetConfigType("env")
 	v.AutomaticEnv()
 	failOnError(v.BindEnv("ETH_JSON_RPC_URL"), "fail on Bind ETH_JSON_RPC_URL")
+	failOnError(v.BindEnv("ETH_ADDRESS"), "fail on Bind ETH_ADDRESS")
 	err := v.ReadInConfig()
 	if err != nil {
 		log.Println("load from environment variable")

learn/go-client.go

@@ -4,7 +4,10 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"math"
+	"math/big"
 
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/leetcode-golang-classroom/golang-ethereum-sample/internal/config"
 )
@@ -21,5 +24,20 @@ func main() {
 		log.Fatalf("Error to get a block: %v", err)
 	}
 	// get latest block number
-	fmt.Println(block.Number())
+	fmt.Println("The block number:", block.Number())
+
+	// find specific address balance
+	addr := config.AppConfig.EthAddress
+	address := common.HexToAddress(addr)
+
+	balance, err := client.BalanceAt(context.Background(), address, nil)
+	if err != nil {
+		log.Fatalf("Error to get the balance:%v", err)
+	}
+	fmt.Println("The balance:", balance)
+	// 1 ether = 10^18 wei
+	fBalance := new(big.Float)
+	fBalance.SetString(balance.String())
+	balanceEther := new(big.Float).Quo(fBalance, big.NewFloat(math.Pow10(18)))
+	fmt.Println("address:", config.AppConfig.EthAddress, "has", balanceEther, "ether")
 }