Question

我有以下JSP类

<form:form method="POST" modelAttribute="task">
        <form:input type="hidden" path="id" id="id"/>
        <table>
            <tr>
                <td><label for="reference">Reference: </label> </td>
                <td><form:input path="reference" id="reference"/></td>
                <td><form:errors path="reference" cssClass="error"/></td>
            </tr>

            <tr>
                <td><label for="cause">Cause: </label> </td>
                <td><form:input path="cause" id="cause"/></td>
                <td><form:errors path="cause" cssClass="error"/></td>
            </tr>
            <tr>
                <td><label for="offense">Offense: </label> </td>
                <td><form:select path="offense.id" items="${offenses}" required="true" itemLabel="offense" itemValue="id"/>  </td>
                <td><form:errors path="offense" cssClass="error"/></td>
            </tr>

            <tr>
                <td colspan="3">
                    <c:choose>
                        <c:when test="${edit}">
                            <input type="submit" value="Update"/>
                        </c:when>
                        <c:otherwise>
                            <input type="submit" value="Register"/>
                        </c:otherwise>
                    </c:choose>
                </td>
            </tr>
        </table>
    </form:form>

并且控制器方法看起来像这样

@RequestMapping(value = {"/new"}, method = RequestMethod.GET)
public String newTask(ModelMap model) {
    Task task = new Task();
    List<Offense> offenses = offenseService.findAllOffenses();

    model.addAttribute("task", task);
    model.addAttribute("edit", false);
    model.addAttribute("offenses", offenses);
    return "registration";
}

@RequestMapping(value = {"/new"}, method = RequestMethod.POST)
public String saveEmployee(@Valid Task task, BindingResult result,
        ModelMap model) {

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

    if (!taskService.isTaskUniqueReference(task.getReference())) {
        FieldError referenceError = new FieldError("Task", "reference", messageSource.getMessage("non.unique.reference", new String[]{String.valueOf(task.getReference())}, Locale.getDefault()));
        result.addError(referenceError);
        return "registration";
    }

    taskService.saveTask(task);

    model.addAttribute("success", "Task " + task.getReference() + " registered successfully");
    return "success";
}

问题是，当我点击提交并触发错误时，例如重复的参考字段，错误会在参考字段的左侧正确显示，但下拉菜单中的选项会消失，为什么是初始模型图数据丢失了？我怎么能解决这个问题，我试图在hasErrors（）的情况下将攻击添加到模型图中，但没有解决问题。

Answer 1

试试这个：

List<Offense> offenses = offenseService.findAllOffenses();
if (!taskService.isTaskUniqueReference(task.getReference())) {
    FieldError referenceError = new FieldError("Task", "reference",
              messageSource.getMessage("non.unique.reference",
              new String[] { String.valueOf(task.getReference()) }, Locale.getDefault()));
    result.addError(referenceError);
    model.addAttribute("offenses", offenses);
    return "registration";
}

提交spring mvc后，下拉数据消失

1 个答案: