java - Spring MVC : Neither BindingResult nor plain target object for bean name 'user' available as

Question

我正在使用 Spring MVC，但出现以下错误:

Caused by: java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'user' available as request attribute

当我们没有在 Controller 代码中传递/添加模型中的对象时，通常会发生此错误。但我已经这样做了，但我仍然收到错误。

我在互联网上查看了完全相同错误的解决方案，但所有这些都指向在 Controller 中添加新对象。不知道为什么对我来说它不起作用。

不确定我做错了什么。

这是我在 login.html 中的表单:

<div class="container">
  <div class="starter-template">
    <h2>Login</h2>
  </div>

  <form th:object="${user}" th:method="post" th:action="validateUser" class="form-horizontal">
    <table class="table table-striped">
      <tr>
        <td>
          <div class="control-group">
            <label class="control-label">Email</label>
          </div>
        </td>
        <td>
          <div class="controls">
            <input type="text" class="form-control" th:field="*{emailAddress}"/>
            <label class="control-label"></label>
          </div>
        </td>
      </tr>
      <tr>
        <td>
          <div class="control-group">
            <label class="control-label">Password</label>
          </div>
        </td>
        <td>
          <div class="controls">
            <input type="password" class="form-control" th:field="*{password}"/>
            <label class="control-label"></label>
          </div>
        </td>
      </tr>
      <tr>
        <td></td>
        <td>
          <div class="form-actions pull-right">
            <input type="submit" name="_eventId_validateUser" value="Login"
                   class="btn btn-success" tabindex="5"/>
            <input type="submit" name="_eventId_cancel" value="Cancel"
                   class="btn btn-danger" tabindex="6"/>
          </div>
        </td>
      </tr>
    </table>
  </form>
</div>

我的 Controller.java:

package com.niti.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.niti.authentication.service.AuthenticationService;
import com.niti.bo.UserBO;
import com.niti.service.exception.ServiceBusinessException;

@Controller
public class LoginController {

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

    @Autowired
    private AuthenticationService authenticationService;

    @RequestMapping(value = "/login", method = RequestMethod.GET)
    public String login(Model model) {
        model.addAttribute("user", new UserBO());
        return "login";
    }

    @RequestMapping(value = "/validateUser", method = RequestMethod.POST)
    public String processLoginInfo(@ModelAttribute UserBO userBO) throws ServiceBusinessException {
        UserBO user = authenticationService.authenticateUser(userBO.getEmailAddress(), userBO.getPassword());

        return "userDetails";
    }       
}

Answer 1

在你绑定(bind)的html表单中

th:object="${user}" // user

另一方面，您在 Controller 方法 processLoginInfo 中默认绑定(bind)了一个 userBO。

你的方法应该是这样的

@RequestMapping(value="/validateUser" , method=RequestMethod.POST)
public String processLoginInfo(@ModelAttribute("user") UserBO userBO) throws ServiceBusinessException {
    UserBO user = authenticationService.authenticateUser(userBO.getEmailAddress(), userBO.getPassword());

    return "userDetails";
}