Snippet: Subtract month (golang)

main.go

package main

import (
	"fmt"
	"time"
)
  
func subtractMonth(startT time.Time, idx int) (result time.Time, err error) {
	loc, err := time.LoadLocation("Asia/Seoul")
	if err != nil {
		log.Println(err)
		return
	}
	y, m, _ := startT.Date()
	return time.Date(y, m-time.Month(idx), 1, 0, 0, 0, 0, loc), nil
}

func main() {
	
	start := "2020-06-30 05:10:59"
	startT, err := time.Parse(global.LAYOUTYMDT, start)
	if err != nil {
		log.Println(err)
	}
	
	result := subtractMonth(start, 1)
	fmt.Println(result)
	// 2020-05-01 00:00:00 +0900 KST
}