@RequestMapping("/calendar")
    public ModelAndView calendar(@RequestParam @Nullable Map<String, String> param){

        System.out.println("param - Calendar");
        System.out.println(param);

        if(param == null){
            System.out.println("first calendar");
            ModelAndView modelAndView = new ModelAndView("calendar");
            return modelAndView;
        }else{
            System.out.println("Got the param");
            System.out.println(param);
            String selectedDate = param.get("selectedDate");
            System.out.println(selectedDate);
            List<Todo> result = calendarService.getTodoList(selectedDate);

            System.out.println(result);

            ModelAndView modelAndView = new ModelAndView("calendar");
            modelAndView.addObject("todo", result);

            System.out.println("Send the result");

            return modelAndView;
        }
    }

    @Transactional
    @RequestMapping(value="/readCalendar", produces="text/html;charset=UTF-8", method = RequestMethod.POST)
    @ResponseBody
    public String readCalendar(@RequestParam Map<String, String> param, RedirectAttributes re) throws ParseException {

        //String selectedDate = param.get("selectedDate");
        System.out.println("param - readCalendar");
        System.out.println(param);
        
        re.addAttribute("param", param.get("selectedDate"));
        System.out.println(re);
        
        //여기서부터 안됨
        return "redirect:/calendar";
    }