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java - BindingResult 和 bean 的普通目标对象都不能用作请求属性

转载 作者：行者123 更新时间：2023-11-29 01:06:03 25 4
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我正在尝试使用 Java、Spring、Hibernate 和 MySQL 制作简单的 CRUD Web 应用程序。我遇到的问题是我无法显示将新项目(比萨饼)添加到数据库的表单。

这是我的 Controller :

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.support.SessionStatus;

@Controller
public class PizzaController {

  @Autowired private PizzaDao pizzaDao;

  @RequestMapping(method=RequestMethod.GET, value="/")
  public String indexPage(Model model) {
    List<Pizza> pizzas = pizzaDao.getAll();
    model.addAttribute("pizzas", pizzas);
    return "index";
  }
  @RequestMapping(method=RequestMethod.GET, value="Pizza/pizzalist")
  public String pizzalist(Model model) {
    List<Pizza> pizzas = pizzaDao.getAll();
    model.addAttribute("pizzas", pizzas);
    return "pizzalist/pizzalist";
  }
  @RequestMapping(method=RequestMethod.POST, value="Pizza/pizzalist/add")
  public String add(@ModelAttribute("mypizza") Pizza pizza) { //, BindingResult result,         SessionStatus status, ModelMap mmap) {
    //mmap.addAttribute("pizza",pizza);
    pizzaDao.add(pizza);
    //status.setComplete();
    return "pizzalist/pizzalist";
  }
  @RequestMapping(method=RequestMethod.GET, value="Pizza/pizzalist/delete")
  public String delete(@RequestParam("id")long id, Model model) {
    pizzaDao.delete(id);
    List<Pizza> pizzas = pizzaDao.getAll();
    model.addAttribute("pizzas", pizzas);
    return "pizzalist/pizzalist";
  }
  @RequestMapping(method=RequestMethod.POST, value="Pizza/edit")
  public String edit(Model model) {
    List<Pizza> pizzas = pizzaDao.getAll();
    model.addAttribute("pizzas", pizzas);
    return "pizzalist/pizzalist";
  }
}

并查看:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ include file="/WEB-INF/jsp/includes.jsp"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"     "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Available pizzas</title>
</head>
<body>
    <h1>List of All Pizzas</h1>
    <table border="1">
        <c:forEach var="p" items="${pizzas}">
            <tr>
                <td>${p.name}</td><td>${p.price}</td><td><a href="pizzalist/delete?id=${p.id}">Delete</a></td>
            </tr>
        </c:forEach>
    </table>
    <br />
    <h1>Add new pizza</h1>
    <form:form modelAttribute="mypizza" method="POST" action="pizzalist/add">
    <table>
        <tr>
            <td>Name</td>
            <td><form:input path="name" /></td>
        </tr>
        <tr>
            <td>Price</td>
            <td><form:input path="price" /></td>
        </tr>
        <tr>
            <td colspan="2">
                <input type="submit" name="action" value="Add" />
            </td>
        </tr>
    </table>
    </form:form>
    <br />
    <a href="/pizzashop">Go back to home page</a>
</body>
</html>

当我只留下显示带有“删除”链接的可用比萨饼的表格时，一切都显示正常，删除也正常。

我猜表单和 Controller @ModelAttribute 有问题，但我找不到确切的问题所在，我在 Controller 中添加了与表单相同的属性 - “mypizza”，这应该可以工作(至少从我的角度来看是这样的)能够在 Google 上找到)。

有人能告诉我是什么阻止了这个应用程序的工作以及如何解决这个问题吗？如果需要其他配置文件，我可以提供。

更新:

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'mypizza' available as request attribute
org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:141)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getBindStatus(AbstractDataBoundFormElementTag.java:179)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getPropertyPath(AbstractDataBoundFormElementTag.java:199)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getName(AbstractDataBoundFormElementTag.java:165)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.autogenerateId(AbstractDataBoundFormElementTag.java:152)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.resolveId(AbstractDataBoundFormElementTag.java:143)
org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.writeDefaultAttributes(AbstractDataBoundFormElementTag.java:127)
org.springframework.web.servlet.tags.form.AbstractHtmlElementTag.writeDefaultAttributes(AbstractHtmlElementTag.java:421)
org.springframework.web.servlet.tags.form.InputTag.writeTagContent(InputTag.java:142)
org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:103)
org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:80)
org.apache.jsp.WEB_002dINF.jsp.pizzalist.pizzalist_jsp._jspx_meth_form_005finput_005f0(pizzalist_jsp.java:243)
org.apache.jsp.WEB_002dINF.jsp.pizzalist.pizzalist_jsp._jspx_meth_form_005fform_005f0(pizzalist_jsp.java:194)
org.apache.jsp.WEB_002dINF.jsp.pizzalist.pizzalist_jsp._jspService(pizzalist_jsp.java:103)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238)
org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:263)
org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1208)
org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:992)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:939)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)

最佳答案

关于这个方法:

@RequestMapping(method=RequestMethod.GET, value="/")
  public String indexPage(Model model) {
    List<Pizza> pizzas = pizzaDao.getAll();
    model.addAttribute("pizzas", pizzas);
    return "index";
  }

您应该添加以下行:

model.addAttribute("mypizza", new Pizza());

form:form 需要一个与您定义的 modelAttribute 相对应的“空”模型。

关于java - BindingResult 和 bean 的普通目标对象都不能用作请求属性，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/22364886/

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