我正在创建一个用于向数据库添加新角色实体的表单，我遇到以下错误：
Neither BindingResult nor plain target object for bean name 'id' available as request attribute
我已经在StackOverflow上尝试了几个相同错误的解决方案，但是没有一个能够工作。下面显示的是我的角色模型和控制器类，以及它们的相关模板：
Role.java
@Entity
public class Role {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@NotNull
private String name;
@OneToMany(mappedBy = "role")
private List<Collaborator> collaborators = new ArrayList<>();
@ManyToMany(mappedBy = "roles")
private List<Project> projects = new ArrayList<>();
public Role() {
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<Collaborator> getCollaborators() {
return collaborators;
}
public void setCollaborators(List<Collaborator> collaborators) {
this.collaborators = collaborators;
}
public List<Project> getProjects() {
return projects;
}
public void setProjects(List<Project> projects) {
this.projects = projects;
}
}
RoleController.java
@Controller
public class RoleController {
@Autowired
private RoleService roleService;
@GetMapping("/roles")
public String listRoles(Model model) {
List<Role> roles = roleService.findAll();
model.addAttribute("roles", roles);
return "role/roles";
}
@PostMapping("/roles")
public String addCategory(@Valid Role role, BindingResult result, RedirectAttributes redirectAttributes) {
if(result.hasErrors()) {
redirectAttributes.addFlashAttribute("org.springframework.validation.BindingResult.category", result);
redirectAttributes.addFlashAttribute("role", role);
return "redirect:/roles";
}
roleService.save(role);
redirectAttributes.addFlashAttribute("flash", new FlashMessage("Role successfully added!", FlashMessage.Status.SUCCESS));
return "redirect:/roles";
}
}
roles.html
<!DOCTYPE html>
<html>
<head th:replace="layout :: head('roles')"></head>
<body>
<header th:replace="layout :: header"></header>
<nav th:replace="layout :: nav"></nav>
<div th:replace="layout :: flash"></div>
<section>
<div class="container wrapper">
<form>
<h2>Manage Roles</h2>
<div>
<ul class="checkbox-list">
<li th:each="role : ${roles}"><span class="primary" th:text="${role.name}">Role Name</span></li>
</ul>
</div>
<form th:object="${role}" th:action="@{/roles}" method="post" class="actions add-new-role">
<input type="hidden" th:field="*{id}"/>
<input type="text" th:field="*{name}" placeholder="Role Name"/>
<input type="submit" value="Submit" class="button"/>
</form>
</form>
</div>
</section>
</body>
</html>
堆栈追踪：
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'id' available as request attribute
at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:144) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.thymeleaf.spring4.util.FieldUtils.getBindStatusFromParsedExpression(FieldUtils.java:401) ~[thymeleaf-spring4-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.spring4.util.FieldUtils.getBindStatus(FieldUtils.java:328) ~[thymeleaf-spring4-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.spring4.util.FieldUtils.getBindStatus(FieldUtils.java:294) ~[thymeleaf-spring4-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.spring4.processor.attr.AbstractSpringFieldAttrProcessor.processAttribute(AbstractSpringFieldAttrProcessor.java:98) ~[thymeleaf-spring4-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.processor.attr.AbstractAttrProcessor.doProcess(AbstractAttrProcessor.java:87) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.processor.AbstractProcessor.process(AbstractProcessor.java:212) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.Node.applyNextProcessor(Node.java:1017) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.Node.processNode(Node.java:972) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.dom.Document.process(Document.java:93) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1155) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1060) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1011) ~[thymeleaf-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.spring4.view.ThymeleafView.renderFragment(ThymeleafView.java:335) ~[thymeleaf-spring4-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.thymeleaf.spring4.view.ThymeleafView.render(ThymeleafView.java:190) ~[thymeleaf-spring4-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1286) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1041) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:984) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.23.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:108) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) ~[tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478) [tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459) [tomcat-embed-core-8.5.23.jar:8.5.23]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.23.jar:8.5.23]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_131]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_131]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.23.jar:8.5.23]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_131]
编辑：感谢您帮助解决问题。
答案 0 :(得分：-1)
我认为你应该在使用它之前确认id不为null，当你使用值为null时，thymeleaf有问题。
答案 1 :(得分：-1)
我最终得到了两个模板，一个角色索引和一个用于添加新角色的表单。我还有三个控制器方法：2个获取方法（1个用于索引，1个用于表单）和1个post方法（用于添加新角色）。
<强> RoleController.java
@Controller
public class RoleController {
@Autowired
private RoleService roleService;
// Index of roles
@GetMapping("/roles")
public String getRoles(Model model) {
List<Role> roles = roleService.findAll();
model.addAttribute("roles", roles);
return "role/index";
}
// New role form
@GetMapping("/roles/add")
public String newRoleForm(Model model) {
if(!model.containsAttribute("role")) {
model.addAttribute("role", new Role());
}
model.addAttribute("action","/roles");
model.addAttribute("heading","New Role");
model.addAttribute("submit","Add");
return "role/form";
}
// Add new role
@PostMapping(value = "/roles")
public String addNewRole(@Valid Role role, BindingResult result, RedirectAttributes redirectAttributes) {
if(result.hasErrors()) {
redirectAttributes.addFlashAttribute("org.springframework.validation.BindingResult.category",result);
redirectAttributes.addFlashAttribute("role", role);
return "redirect:/roles/add";
}
roleService.save(role);
redirectAttributes.addFlashAttribute("flash", new FlashMessage("Role successfully added!", FlashMessage.Status.SUCCESS));
return "redirect:/roles";
}
}
<强>作用/ index.html中
<!DOCTYPE html>
<html>
<head th:replace="layout :: head('roles')"></head>
<body>
<header th:replace="layout :: header('Role', '/roles/add')"></header>
<div th:replace="layout :: flash"></div>
<nav th:replace="layout :: nav"></nav>
<section>
<div class="container wrapper">
<form>
<h2>Manage Roles</h2>
<div>
<ul class="checkbox-list">
<li th:each="role : ${roles}"><span class="primary" th:text="${role.name}">Role Name</span></li>
</ul>
</div>
<br>
</form>
</div>
</section>
<div th:replace="layout :: scripts"></div>
</body>
</html>
<强>作用/ form.html
<!DOCTYPE html>
<html>
<head th:replace="layout :: head('roles')"></head>
<body>
<header>
<div class="container">
<div class="site-header">
<a class="logo" th:href="@{/}">InstaTeam</a>
</div>
</div>
</header>
<div th:replace="layout :: flash"></div>
<nav th:replace="layout :: nav"></nav>
<section>
<div class="container wrapper">
<form th:action="@{${action}}" method="post" th:object="${role}">
<h2 th:text="${heading}">New Role</h2>
<input type="hidden" th:field="*{id}"/>
<div class="actions add-new-role">
<input type="text" th:field="*{name}" placeholder="Role Name"/>
<button th:text="${submit}" type="submit" class="button">Add</button>
</div>
</form>
</div>
</section>
<div th:replace="layout :: scripts"></div>
</body>
</html>