既不是 BindingResult 也不是 bean 的普通目标对象答案

【问题标题】：Neither BindingResult nor plain target object for bean既不是 BindingResult 也不是 bean 的普通目标对象
【发布时间】：2020-02-21 00:25:09
【问题描述】：

我尝试了很多很多组合 - 尝试使用 ModelAndView 并返回 mav 并尝试 model.addAttribute 并返回 String，并在 jsp 页面中编写 - 自动选择和 customerGet 并尝试 customerPost，但没有任何一种组合帮助我。

如何更正代码？我只需要一个 WORKING 示例来了解如何将代码从控制器发送到 jsp，找不到任何关于它的工作示例 - 因为它们不适用于我的 mvc+jsp

@Getter
@Setter
@Entity
@Table(name = "customer")
@NoArgsConstructor
@EqualsAndHashCode
public class Customer implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String firstName;
private String lastName;

@OneToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinColumn(name = "address_id")
private Address address;

@OneToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinColumn(name = "user_id")
private User user;



@Getter
@Setter
@Entity
@Table(name = "address")
@NoArgsConstructor
@EqualsAndHashCode
public class Address implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

private String country;
private String city;
private String street;
private String flat;

@OneToOne(mappedBy = "address")
private Customer customer;


@Getter
@Setter
@Entity
@Table(name = "users")
@NoArgsConstructor
@EqualsAndHashCode(of = "email")
public class User implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

private String email;
private String password;
private boolean enable;

@OneToOne(mappedBy = "user")
private Customer customer;

我的错误代码

    @Controller
    @RequestMapping(value = "index")
    public class HomeController {

        @Autowired
        private CustomerService customerService;


    //    @RequestMapping(method = RequestMethod.GET)
    //    public ModelAndView  getRegistrationForm() {
    //        Customer customer = new Customer();
    //        User user = new User();
    //        Address address = new Address();
    //        customer.setAddress(address);
    //        customer.setUser(user);
    //        ModelAndView modelAndView = new ModelAndView();
    //        modelAndView.addObject("customer", customer);
    ////        model.addAttribute("customer", new Customer());
    //        modelAndView.setViewName("customer");
    //        return modelAndView;
    ////        return new ModelAndView("register", "customer", customer);
    ////        return "index";
    //    }

        @RequestMapping(value = "/index", method = RequestMethod.GET)
        public String customer(Model model) {
    //            ModelAndView modelAndView = new ModelAndView();
    //        Customer customer = new Customer();
    //        User user = new User();
    //        Address address = new Address();
    //        customer.setAddress(address);
    //        customer.setUser(user);
    //        model.addAttribute(user);
    //        model.addAttribute(address);
    //        model.addAttribute("customer", customer);
                    model.addAttribute("customerGet", new Customer());
                return "index";
        }

    //        return new ModelAndView("customer", "command", customer);
    //    }

        @RequestMapping(value = "/addCustomer", method = RequestMethod.POST)
        public String registerCustomer(@Valid @ModelAttribute(value = "customerPost") Customer customer, Model model,
                                       BindingResult result) {
            if (result.hasErrors())
                return "index";
            customerService.createCustomer(customer);
            model.addAttribute("registrationSuccess", "Registered Successfully.");
            return "index";
        }

    //    @RequestMapping(value = "/addCustomer", method = RequestMethod.POST)
    //    public String registerCustomer
    //            (@ModelAttribute("customer") Customer customer, Model model,
    //             BindingResult result) {
    //        if (result.hasErrors()) return "register";
    //        customerService.createCustomer(customer);
    //        model.addAttribute("registrationSuccess", "Registered Successfully.");
    //        return "redirect:/index";
    //    }
     // @RequestMapping(value = "/addCustomer", method = RequestMethod.POST)
    //    public String addStudent(@ModelAttribute("customer")Customer customer,
    //                             ModelMap model) {
    //        model.addAttribute("firstName", customer.getFirstName());
    //        model.addAttribute("lastName", customer.getLastName());
    //        model.addAttribute("country", customer.getAddress().getCountry());
    //        model.addAttribute("city", customer.getAddress().getCity());
    //        model.addAttribute("street", customer.getAddress().getStreet());
    //        model.addAttribute("flat", customer.getAddress().getFlat());
    //        model.addAttribute("email", customer.getUser().getEmail());
    //        model.addAttribute("password", customer.getUser().getPassword());
    //        customerService.createCustomer(customer);
    //        return "index";
    //    }
        }

我的 application.properties spring-boot

spring.mvc.view.prefix=/WEB-INF/pages/ spring.mvc.view.suffix=.jsp

mybad jsp

<%@ page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags/form" %>
<!DOCTYPE html>
<html>
<head>
    <title>Title</title>
</head>
<body>

<c:url var="addAction" value="/index/addCustomer" ></c:url>

<spring:form action="${addAction}" modelAttribute="customerGet">
    <table>
        <thead>
        <tr>
            <th>Create Student</th>
        </tr>
        </thead>
        <tbody>
      <tr>
          <td>
<%--          <spring:input path="id" readonly="true" size="8"  disabled="true" />--%>
              <spring:hidden path="id" />
          </td>
      </tr>
        <tr>
            <td>first name</td>
            <td><spring:input path="firstName"/></td>
        </tr>
        <tr>
            <td>last name</td>
            <td><spring:input path="lastName"/></td>
        </tr>
        <tr>
            <td>country</td>
            <td><spring:input path="address.country"/></td>
        </tr>
        <tr>
            <td>city</td>
            <td><spring:input path="address.city"/></td>
        </tr>
        <tr>
            <td>street</td>
            <td><spring:input path="address.street"/></td>
        </tr>
        <tr>
            <td>flat</td>
            <td><spring:input path="address.flat"/></td>
        </tr>
        <tr>
            <td>email</td>
            <td><spring:input path="user.email"/></td>
        </tr>
        <tr>
            <td>password</td>
            <td><spring:input path="user.password"/></td>
        </tr>
        </tbody>
    </table>
    <spring:button>add customer</spring:button>
</spring:form>

</body>

</html>

我在http://localhost:8081/index/index 找到页面并在完成表单并选择按钮后再次出现错误我自动重定向到页面在http://localhost:8081/index/addCustomer

Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.

Thu Oct 24 16:14:59 UTC 2019
There was an unexpected error (type=Internal Server Error, status=500).
Neither BindingResult nor plain target object for bean name 'customerGet' available as request attribute
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'customerGet' available as request attribute

当我看到 mysql base 时——我找到了我的实体——我有第二个问题 = 如何更正创建新客户——只有 getmethot 控制器或methot 中的新客户需要这样写？使用 hibernate-jpa - crud 存储库

   Customer customer = new Customer();
   User user = new User();
   Address address = new Address();
   customer.setAddress(address);
   customer.setUser(user);

【问题讨论】：

当您尝试加载页面时会发生什么？您要访问哪个 URL？你在控制器中映射customer 方法的方式是/index/index，这就是你要打的吗？
ooo...我看到localhost:8081/index/index中的表格
但我想在 localhost:8081/index 中看到它，添加对象后不要离开页面，页面必须重新加载
在我完成后出现错误，把它放在我的主要帖子的末尾
我再次遇到错误 - 在每个 url 中，例如 localhost:8081/index/index localhost:8081/index localhost:8081/index/addCustomer 有什么问题？？？？？？

标签： java spring-boot spring-mvc jsp model-view-controller

【解决方案1】：

当您期望视图中有一个对象但未将其添加到模型中时，会引发 BindingResult 错误。（在您的情况下：“customerGet”）对您的代码进行简短分析，您有：

<spring:form action="${addAction}" modelAttribute="customerGet">

=> 您必须在返回此视图的所有控制器方法中具有 model.addAttribute("customerGet", new Customer())。返回索引视图分两种情况：

GET /index/index => 在这里，一切顺利
POST /index/addCustomer => 你没有这里有它，它会绑定结果失败。

【讨论】：

但我需要这个吗？在get方法中
客户 customer = new Customer();用户用户 = 新用户（）；地址地址=新地址（）；客户.setAddress(地址); customer.setUser(user);
是的，您需要在 GET 和 POST 方法中都有 model.addAttribute("customerGet",.. )。由于双向关系，通常在视图中您永远不会直接返回实体。
如果你有 user.email => 客户必须有一个非空的用户对象否则会失败，所以你必须添加一个非空用户的客户对象，地址对象。
我看到了这段代码并尝试去做。我该怎么做？ @RequestMapping(value = "/customer/registration") public ModelAndView getRegistrationForm() { Customer customer = new Customer();用户用户 = 新用户（）； BillingAddress ba = new BillingAddress(); ShippingAddress sa = new ShippingAddress();客户.setShippingAddress(sa);客户.setBillingAddress(ba);客户.setUsers（用户）； return new ModelAndView("register", "customer", customer); }

【解决方案2】：

您收到BindingResult 错误是因为您没有返回您放置在模型和视图中的CustomerGet 对象，只需返回字符串“index”您只是将用户发送到index.jsp 而没有填充表单的模型属性。您的客户方法需要从您的customer 方法返回一个ModelAndView 对象。如果您将 customer 方法更改为如下所示，它应该可以工作：

@RequestMapping(value = "/", method = RequestMethod.GET)
  public ModelAndView customer(Model model) {
    ModelAndView modelAndView = new ModelAndView("index");
    Customer customer = new Customer();
    customer.setAddress(new Address());
    customer.setUser(new User());
    model.addAttribute("customerGet", customer);

    return modelAndView;
}

这会创建一个ModelAndView 对象，指定“index”作为视图的jsp 页面，然后用用户和地址填充一个新的客户对象，并将其放在模型和视图上。要实际查看填充了值的 for，您显然必须在 Customer 对象的属性上为 firstName、lastName 等设置值。请注意，我将方法上的 @RequestMapping 更改为“/”，以便页面将可以在localhost:8081/index 而不是localhost:8081/index/index 获得。

【讨论】：