golang parse environment variable as struct value

ParseStructWithEnv.go

// first set a env var like SERVER_PORT=8888
var (
	Cfg Config
)

type Config struct {
	Server   Server
	Clinet   Clinet
	LogLevel string
}

type Server struct {
	Port     int
	ListenIP string
	LogLevel string
}

type Clinet struct {
	ServerPort     int
	ServerListenIP string
	Token          string
}

ParseStructWithEnv(&Cfg, "")
println(Cfg.Server.Port)

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//ParseStructWithEnv 解析struct tag并检测是否存在符合规则的环境变量 如果存在则套用环境变量的值 输入的值必须是指针地址,比如*A而不是**A
//ParseStructWithEnv golang parse environment variable as struct value,first parameter must be a pointer struct ,such as *A not **A 
func ParseStructWithEnv(o interface{}, rootNodeName string) {
	tp := reflect.TypeOf(o)
	var val reflect.Value

	if tp.Kind() == reflect.Ptr {
		ov := reflect.ValueOf(o)
		val = reflect.Indirect(ov)
	} else {
		val = reflect.ValueOf(o)
	}

	for i := 0; i < val.NumField(); i++ {
		if val.Field(i).Kind() == reflect.Struct {
			ParseStructWithEnv(val.Field(i).Addr().Interface(), val.Type().Field(i).Name)
		} else {
			envName := StrToEnvName(rootNodeName + "_" + val.Type().Field(i).Name)
			env := os.Getenv(envName)
			if env == "" {
				continue
			}
			switch val.Field(i).Type().Kind() {
			case reflect.Bool:
				v, _ := strconv.ParseBool(env)
				val.Field(i).SetBool(v)
			case reflect.Int:
				v, _ := strconv.ParseInt(env, 10, 64)
				val.Field(i).SetInt(v)
			case reflect.String:
				val.Field(i).SetString(env)
			}
		}
	}
}