1.Monthは time.Month(month) にする
func Handler(w http.ResponseWriter, r *http.Request) {
year , _ := strconv.Atoi(r.PostFormValue("year"));
month, _ := strconv.Atoi(r.PostFormValue("month"));
day, _ := strconv.Atoi(r.PostFormValue("day"));
start := time.Date(year, time.Month(month), day, 0, 0, 0, 0, time.Local)
fmt.Println(start.Format("2006-1-2 15:04:05"));
}
2.結果
2022-1-3 00:00:00