Spring MVC Controller , pass a bean between two method

I have started to learn Spring MVC by developping a simple SPRING MVC application .

I have created a JSP file for listing - Editing a list of users like this :

When I click on the "Edit" link ( from list item ) , the form should be populated by the Item information , so the user can edit informations and save the item ( Note that this form is used for create / Edit an item)

This is the code related to the JSP file :

<c:url var="addAction" value="/admin/users/add"></c:url>

<form:form action="${addAction}" commandName="user">

    <table>

        <c:if test="${!empty user.adminName}">
            <tr>
                <td><form:label path="id">
                        <spring:message text="ID" />
                    </form:label></td>
                <td><form:input path="id" readonly="true" size="8"
                        disabled="true" /> <form:hidden path="id" /></td>
            </tr>
        </c:if>

        <tr>
            <td><form:label path="adminName">
                    <spring:message text="Name" />
                </form:label></td>
            <td><form:input path="adminName" /></td>
        </tr>

        <tr>
            <td><form:label path="adminEmail">
                    <spring:message text="adminEmail" />
                </form:label></td>
            <td><form:input path="adminEmail" /></td>
        </tr>

        <tr>

            <td><form:select path="groups" items="${groupList}" /></td>
        </tr>


        <tr>
            <td colspan="2"><c:if test="${!empty user.adminName}">
                    <input type="submit" value="<spring:message text="Edit Person"/>" />
                </c:if> <c:if test="${empty user.adminName}">
                    <input type="submit" value="<spring:message text="Add Person"/>" />
                </c:if></td>
        </tr>
    </table>
</form:form>





<br>
<div class="bs-example">
    <table class="table">
        <thead>
            <tr>
                <th>Row</th>
                <th>First Name</th>
                <th>Email</th>
            </tr>
        </thead>


        <tbody>

            <c:forEach var="i" items="${users}">

                <tr>
                    <td>${i.id}</td>
                    <td>${i.firstName}</td>
                    <td>${i.adminEmail}</td>

                    <td><a href="<c:url value='/admin/users/edit/${i.id}'/>">Edit</a></td>
                    <td><a href="<c:url value='/admin/users/remove/${i.id}'/>">Delete</a></td>


                </tr>

            </c:forEach>

        </tbody>

    </table>
</div>

My controlers Methods are :

    @Controller
@RequestMapping(value = "/admin/users/")
public class UserController {

    private static final Logger LOGGER = LoggerFactory
            .getLogger(UserController.class);

    @Autowired
    UserService userService;

    @Autowired
    GroupService groupService;

    @Autowired
    LabelUtils messages;

    @Autowired
    private BCryptPasswordEncoder passwordEncoder;


    // @PreAuthorize("hasRole('STORE_ADMIN')")
    @RequestMapping(value = "list.html", method = RequestMethod.GET)
    public String displayUsers(Model model) throws Exception {

        List<User> users = userService.listUser();

        List<Group> groups = groupService.list();

        List<String> groupList = new ArrayList<String>();

        model.addAttribute("users", users);
        model.addAttribute("user", new User());

        for (Group group : groups) {

            groupList.add(group.getGroupName());

        }

        model.addAttribute("groupList", groupList);

        return "admin/userAdmin";

    }

    @RequestMapping("remove/{id}")
    public String removePerson(@PathVariable("id") int id) {

        User user = userService.getById((long) id);

        try {
            userService.delete(user);
        } catch (ServiceException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return "redirect:/admin/users/list.html";
    }

    // For add and update person both
    @RequestMapping(value = "add" , method = RequestMethod.POST)
    public String addPerson(@ModelAttribute("user") User user,
            BindingResult result) {

        if (result.hasErrors()) {
            return "error";
        }

        try {
            if (user.getId() == 0) {
                // new person, add it

                this.userService.create(user);

            } else {
                // existing person, call update
                this.userService.saveOrUpdate(user);
            }

        } catch (ServiceException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return "redirect:/admin/users/list.html";


    }

    @RequestMapping(value = "edit/{id}" )
    public String editPerson(@PathVariable("id") int id  , Model model) {



        // Prepare Groups

        List<Group> groups = groupService.list();

        List<String> groupList = new ArrayList<String>();

        for (Group group : groups) {

            groupList.add(group.getGroupName());

        }

        model.addAttribute("groupList", groupList);

        model.addAttribute("user", this.userService.getById((long) id));
        model.addAttribute("users", this.userService.list());

        return "admin/userAdmin";

    }


}

The problem is when I click on edit link , The form is correcly populated by Item information , so the user can edit retreived data , but the object "user" retreived from method "editPerson" in "addPerson" method in controller (

code line : model.addAttribute("user", this.userService.getById((long) id)); in editPerson method ) have all the other fields null so when I merge data , the save action fails .

Example : The user Item has an other field "AdminAPassword" not printed in JSP and not changed bu user , when the data are retreived from the form this field is null .

Could you help please

Thanks in Advance