pythonで前月やら今月の末尾初日返す

前月1日を出す

def getLastMonthStartDay():
    # 今日を取得
    today = datetime.datetime.today()
    # 当月1日を出す
    thismonth = datetime.datetime(today.year, today.month, 1)
    # 前月末日を出す
    lastmonth = thismonth + datetime.timedelta(days=-1)
    # 前月1日を出す
    lastmonthFirstday =  datetime.datetime(lastmonth.year, lastmonth.month, 1)
    print(lastmonthFirstday.strftime('%Y-%m-%d'))
    return lastmonthFirstday.strftime('%Y-%m-%d')

来月末日の値を出す

def getNextMonthLastDay():
    # 今日を取得
    today = datetime.datetime.today()
    # 翌々月を出す
    nextmoth = today + relativedelta(months=2)
    # 翌々月1日を出す
    thismonth = datetime.datetime(nextmoth.year, nextmoth.month, 1)
    # 前月末日の値を出す
    lastmonth = thismonth + datetime.timedelta(days=-1)