post方法中相同类型的多个模型属性

Question

我有这个页面，老师可以邀请学生加入平台。这工作得很好，但现在我想在同一页面上实现多个邀请。简而言之，现在有一种表格可以一次邀请 1 名学生，但我想将其扩展到 5 名学生的一次发布方法。

这是邀请1名学生的页面：

<div class="container">
<div class="wrapper">
    <form class="form-activate" th:action="@{/invite}" method="post" th:object="${user}">
        <h2 class="form-activate-heading" th:text="#{invite.title}">Nodig een student uit</h2>
        <p th:text="#{invite.email}">Vul hier het e-mailadres in van de student die je wil uitnodigen:</p>       
        <div class="form-group">
            <input type="text" name="email" id="email" class="form-control input-lg" data-validation="email"
                   placeholder="Email" tabindex="2" th:attr="placeholder=#{general.email}"/>
        </div>
        <div class="row">
            <div class="col-xs-6 col-sm-6 col-md-6">
                <input type="submit" class="btn btn-secondary" value="Invite"  th:attr="value=#{invite.enter}"/>
            </div>
        </div>
    </form>
</div>

现在我尝试为 2 个用户修改此页面：

<div class="container">
<div class="wrapper">
    <form class="form-activate" th:action="@{/invite}" method="post">
        <h2 class="form-activate-heading" th:text="#{invite.title}">Nodig een student uit</h2>
        <p th:text="#{invite.email}">Vul hier het e-mailadres in van de student die je wil uitnodigen:</p>
        <div class="form-group" th:object="${user}">
            <input type="text" name="email" th:field="*{email}" class="form-control input-lg" data-validation="email"
                   placeholder="Email" tabindex="2" th:attr="placeholder=#{general.email}"/>
        </div>
        <div class="form-group" th:object="${user}">
            <input type="text" name="email" th:field="*{email}" class="form-control input-lg" data-validation="email"
                   placeholder="Email" tabindex="2" th:attr="placeholder=#{general.email}"/>
        </div>
        <div class="row">
            <div class="col-xs-6 col-sm-6 col-md-6">
                <input type="submit" class="btn btn-secondary" value="Invite"  th:attr="value=#{invite.enter}"/>
            </div>
        </div>
    </form>
</div>

然后在我的 post 方法中，我尝试这样做：

@RequestMapping(value="/invite", method = RequestMethod.POST)
public ModelAndView SendInvite(ModelAndView modelAndView, @ModelAttribute User user1, @ModelAttribute User user2, BindingResult bindingResult, RedirectAttributes redirectAttributes, HttpServletRequest request){
    List<User> students = new ArrayList<>();
    students.add(user1);
    students.add(user2);
    for (User user : students) {

但页面甚至不再加载，这是我的 get 方法：

 @RequestMapping(value="/invite", method = RequestMethod.GET)
public ModelAndView showInvitePage(ModelAndView modelAndView, @ModelAttribute User user){
    return modelAndView;
}

这给了我以下错误：

Servlet.service() 用于路径 [] 上下文中的 servlet [dispatcherServlet] 引发异常 [请求处理失败；嵌套异常是 org.thymeleaf.exceptions.TemplateProcessingException: 在执行处理器 'org.thymeleaf.spring4.processor.attr.SpringInputGeneralFieldAttrProcessor' (teacher/invite:20)] 时出错，根本原因 java.lang.IllegalStateException：Bean 名称“用户”的 BindingResult 和普通目标对象都不能用作请求属性 在 org.springframework.web.servlet.support.BindStatus.(BindStatus.java:144)

有没有可能我正在尝试做的事情？

编辑：我正在尝试实施 Aleksandrs 给我的解决方案，但 Spring 抛出错误：

@RequestMapping(value="/invite", method = RequestMethod.GET)
public ModelAndView showInvitePage(ModelAndView modelAndView){
    List<String> emailList = new ArrayList<>();
    modelAndView.addObject(emailList);
    return modelAndView;
}

@RequestMapping(value="/invite", method = RequestMethod.POST)
public ModelAndView SendInvite(ModelAndView modelAndView, List<String> emailList){
    System.out.println(emailList.get(0));

尽管我已经在 Get 方法中实例化了 emailList，但我收到以下错误：

嵌套异常是 org.springframework.beans.BeanInstantiationException: 无法实例化 [java.util.List]: Specified class is an interface] 根本原因 org.springframework.beans.BeanInstantiationException: 无法实例化 [java.util.List]: 指定的类是一个接口

EDIT2：

终于成功了，感谢 Aleksandrs 的帮助！解决方案：

 @RequestMapping(value="/teacher/invite", method = RequestMethod.GET)
public ModelAndView showInvitePage(ModelAndView modelAndView){
    logger.info("Entered showInvitePage function");
    List<String> email = new ArrayList<>();
    modelAndView.addObject("email", email);
    return modelAndView;
}

@RequestMapping(value="/invite", method = RequestMethod.POST)
public ModelAndView SendInvite(ModelAndView modelAndView, @AuthenticationPrincipal User currentUser, @RequestParam List<String> email){
    email.forEach(address -> {
// send the invites
});

还有邀请页面：

 <form class="form-activate" th:action="@{/invite}" method="post" >            
            <p th:text="#{invite.email}">Vul hier het e-mailadres in van de student die je wil uitnodigen:</p>
        </div>
        <div class="form-group">
            <input type="text" name="email" id="email" class="form-control input-lg" data-validation="email"
                   placeholder="Email" tabindex="2" th:attr="placeholder=#{general.email}"/>
        </div>
        <div class="form-group">
            <input type="text" name="email" id="email2" class="form-control input-lg" data-validation="email"
                   placeholder="Email" tabindex="2" th:attr="placeholder=#{general.email}"/>
        </div>
        <div class="form-group">
            <input type="text" name="email" id="email3" class="form-control input-lg" data-validation="email"
                   placeholder="Email" tabindex="2" th:attr="placeholder=#{general.email}"/>
        </div>
        <div class="row">
            <div class="col-xs-6 col-sm-6 col-md-6">
                <input type="submit" class="btn btn-secondary" value="Invite"  th:attr="value=#{invite.enter}"/>
            </div>
        </div>
    </form>

Answer 1

正如Pandian 所说，“用户”绑定了两次，但在这种情况下，您可以使用简单的数组将字符串列表传递给控制器​​。因为实际的用户必须有许多在您的模板中不存在的字段。所以可以推荐在模板中使用这样的东西：

<form class="form-activate" th:action="@{/invite}" method="post">
    <h2 class="form-activate-heading" th:text="#{invite.title}">Nodig een student uit</h2>
    <p th:text="#{invite.email}">Vul hier het e-mailadres in van de student die je wil uitnodigen:</p>
    <div class="form-group">
        <input type="text" name="email[]" class="form-control input-lg" data-validation="email"
               placeholder="Email" tabindex="2" th:attr="placeholder=#{general.email}"/>
    </div>
    <div class="form-group">
        <input type="text" name="email[]" class="form-control input-lg" data-validation="email"
               placeholder="Email" tabindex="2" th:attr="placeholder=#{general.email}"/>
    </div>
    <div class="row">
        <div class="col-xs-6 col-sm-6 col-md-6">
            <input type="submit" class="btn btn-secondary" value="Invite"
                   th:attr="value=#{invite.enter}"/>
        </div>
    </div>
</form>

在控制器中：

@RequestMapping(value = "/invite", method = RequestMethod.POST)
public ModelAndView SendInvite(List<String> emailAddressList) {
    // some stuff here
}

编辑：

所以，我不确定我的 JavaScript 代码是否有效，但在您的情况下，HTML 必须是这样的：

<form class="form-activate" th:action="@{/invite}" method="post" id="myForm">
    <h2 class="form-activate-heading" th:text="#{invite.title}">Nodig een student uit</h2>
    <p th:text="#{invite.email}">Vul hier het e-mailadres in van de student die je wil uitnodigen:</p>
    <div class="form-group">
        <input type="text" name="email[]" id="email" class="form-control input-lg" data-validation="email"
               placeholder="Email" tabindex="2" th:attr="placeholder=#{general.email}"/>
        <span style="cursor: pointer;"
              onclick="myForm.innerHTML = myForm.innerHTML + '' + this.parentNode.cloneNode(true);">+</span>
    </div>
    <div class="row">
        <div class="col-xs-6 col-sm-6 col-md-6">
            <input type="submit" class="btn btn-secondary" value="Invite"
                   th:attr="value=#{invite.enter}"/>
        </div>
    </div>
</form>

在控制器中我会尝试这样做：

@RequestMapping(value = "/invite", method = RequestMethod.POST)
public ModelAndView SendInvite(ModelAndView modelAndView, @RequestParam List<String> email) {
    email.stream()
        .forEach(address -> {
            User u = userService.findByEmail(address);
            if (u == null) {
                // send email here for current user;
            }
        });
    // some other stuff
}

如果你能告诉我一些测试密码，我可以尝试在我的电脑上运行它。

Answer 2

问题：同一模型“用户”在名称为“电子邮件”的同一元素上绑定了两次

下面的代码对我来说很好用

    <form action="#" th:action="@{/accessSite}" method="post">
    <div th:object="${userVO}">
        <table>
            <tr>
                <td>Name:</td>
                <td><input type="text" th:field="*{name}" /></td>
                <td th:if="${#fields.hasErrors('name')}" th:errors="*{name}">Name
                    Error</td>
            </tr>


        </table>
    </div>

    <div th:object="${employeeVO}">
        <table>
            <tr>
                <td>Name:</td>
                <td><input type="text" th:field="*{empname}" /></td>
                <td th:if="${#fields.hasErrors('empname')}" th:errors="*{empname}">Name
                    Error</td>
            </tr>

        </table>
    </div>

提交

  @RequestMapping("/accessSite")
public String accessSite( UserVO userVO, EmployeeVO employeeVO,BindingResult bindingResult) {
    if (bindingResult.hasErrors()) {
        return "form";
    }
    return "result";
}