Question

here is the jsp:

<c:if test="${!empty USERS}">
    <form:form method="post" action="requestForFriends.html" commandName="user">
        <form:select path="userName">
            <c:forEach items="${USERS}" var="user">
                <form:option value="${user.userName}"></form:option>
            </c:forEach>
        </form:select>

        <input type="submit" value="Send freindship request" />
    </form:form>
</c:if>

here is the controller’s relevant part:

@RequestMapping("/toAddFriend")
public ModelAndView toAddNewFriend() {
    Map<String, Object> model = new HashMap<String, Object>();
    model.put("USERS", userService.getUsers());
    ModelAndView ret=new ModelAndView("addFriend", model);
    ret.addObject("user", new User());

    return ret;
}

if I do the code above then a brand new User object will be created when I submit the form. But when I click “submit” I would like to get one of the ALREADY EXISTING User instance, which are clearly present in here:

<c:forEach items="${USERS}" var="user">
    <form:option value="${user.userName}"></form:option>

How can I modify my code to get the existing object?
Actually I know an ugly way to get the existing instance. By submitting the form I can create a new User instance with the same username as the one has that I am looking for. Then in the DaoImpl class I can query for the “old” User which shares the userName with the newly created one. But I guess it is quite wasteful and ugly so I can’t believe that there is no better way.

UPDATE

   <!-- language: lang-java -->

 @RequestMapping(value = "/requestForFriends", method = RequestMethod.POST)
        public ModelAndView requestNewFriend(@ModelAttribute("user") User user, BindingResult result) {
            System.out.println(user.getUserName());
                System.out.println(user.getEmail());
                Map<String, Object> model = new HashMap<String, Object>();
                model.put("USERS", userService.getUsers());
                ModelAndView ret=new ModelAndView("addFriend", model);
                ret.addObject("user", new User());

                return ret;

            }

Answer 1

  @ModelAttribute
    public void fillUsers(Model model) {
        model.addAttribute("USERS", userService.getUsers());
    }

    @ModelAttribute
    public void getUser(@RequestParam(required = false) String userName, Model model) {
        User user = null;
        if (userName != null) {
            user = userService.getUserByName(userName);
        }
        if (user == null) {
            user = new User();
        }
        model.addAttribute("user", user);
    }

    @RequestMapping("/toAddFriend")
    public String toAddNewFriend() {
        return "addFriend";

    }

    @RequestMapping(value = "/requestForFriends", method = RequestMethod.POST)
    public String requestNewFriend(@ModelAttribute("user") User user) {
        System.out.println(user.getUserName());
        System.out.println(user.getEmail());
        return "addFriend";

    }