Java 对于Thymeleaf和Spring MVC，表单值为空

我正在尝试用Thymeleaf和SpringMVC处理表单。 用户应选择一个预订，然后将其保存在表单中

模板如下所示：

<form action="#" th:object="${reservationselectionform}">

                <select th:field="*{reservationSelection}" class="selectpicker" data-live-search="true" style="display: none;" >
                    <option th:each="reservation : ${reservationlist}"
                            th:value="${reservation}"
                            th:text="${reservation.user.userAccount.firstname}">Tyler Durden</option>
                </select>
<button type="submit" class="btn btn-primary" formaction="/checkintest" formmethod="post">Weiter</button>

@RequestMapping(value="choose_reservation", method = RequestMethod.GET)
    public String chose_reservation(ModelMap modelMap{

       modelMap.addAttribute("reservationselectionform", new ReservationSelectionForm());
       return "checkin/choose_reservation";

    }
@RequestMapping("/checkintest")
public String personaldata (ModelMap modelMap,
                                @ModelAttribute("reservationselectionform") ReservationSelectionForm reservationSelectionForm){

       return "checkin/checkintest";
    }

表格很简单，如下所示：

public class ReservationSelectionForm {

private Reservation reservationSelection;

@NotEmpty
private String firstname;

@NotEmpty
private String lastname;

//getter & setter

如果我尝试使用表单设置firstname，则firstname会完全包含在ReservationSelectionForm中

当我传递整个预订对象

（th:value=“${Reservation}”）

时，它在ReservationSelectionForm中总是

null

---

有人能给我解释一下，或者帮我传递整个预订对象吗？

您的选择列表总是空的。