I'm new to springBoot, I tried to built a simple form and added validation. Everything works fine but when I click on submit button with empty subject and name the program throws an error. I'm attaching the files and error for reference. Thanks In advance.
**ERROR**
Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.
Thu May 18 23:36:46 IST 2023
There was an unexpected error (type=Internal Server Error, status=500).
An error happened during template parsing (template: "class path resource [templates/form.html]")
org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates/form.html]")
at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:241)
at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parseStandalone(AbstractMarkupTemplateParser.java:100)
at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:666)
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1098)
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1072)
at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:366)
at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:190)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1401)
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1145)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1084)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:681)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:764)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:890)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1743)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: org.attoparser.ParseException: Error during execution of processor 'org.thymeleaf.spring5.processor.SpringErrorsTagProcessor' (template: "form" - line 93, col 30)
at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:393)
at org.attoparser.MarkupParser.parse(MarkupParser.java:257)
at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:230)
... 48 more
Caused by: org.thymeleaf.exceptions.TemplateProcessingException: Error during execution of processor 'org.thymeleaf.spring5.processor.SpringErrorsTagProcessor' (template: "form" - line 93, col 30)
at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:117)
at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95)
at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633)
at org.thymeleaf.engine.ProcessorTemplateHandler.handleOpenElement(ProcessorTemplateHandler.java:1314)
at org.thymeleaf.engine.TemplateHandlerAdapterMarkupHandler.handleOpenElementEnd(TemplateHandlerAdapterMarkupHandler.java:304)
at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler$InlineMarkupAdapterPreProcessorHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:278)
at org.thymeleaf.standard.inline.OutputExpressionInlinePreProcessorHandler.handleOpenElementEnd(OutputExpressionInlinePreProcessorHandler.java:186)
at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:124)
at org.attoparser.HtmlElement.handleOpenElementEnd(HtmlElement.java:109)
at org.attoparser.HtmlMarkupHandler.handleOpenElementEnd(HtmlMarkupHandler.java:297)
at org.attoparser.MarkupEventProcessorHandler.handleOpenElementEnd(MarkupEventProcessorHandler.java:402)
at org.attoparser.ParsingElementMarkupUtil.parseOpenElement(ParsingElementMarkupUtil.java:159)
at org.attoparser.MarkupParser.parseBuffer(MarkupParser.java:710)
at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:301)
... 50 more
Caused by: java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'grades' available as request attribute
at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:153)
at org.springframework.web.servlet.support.RequestContext.getBindStatus(RequestContext.java:903)
at org.thymeleaf.spring5.context.webmvc.SpringWebMvcThymeleafRequestContext.getBindStatus(SpringWebMvcThymeleafRequestContext.java:227)
at org.thymeleaf.spring5.util.FieldUtils.getBindStatusFromParsedExpression(FieldUtils.java:306)
at org.thymeleaf.spring5.util.FieldUtils.getBindStatus(FieldUtils.java:253)
at org.thymeleaf.spring5.util.FieldUtils.getBindStatus(FieldUtils.java:227)
at org.thymeleaf.spring5.processor.SpringErrorsTagProcessor.doProcess(SpringErrorsTagProcessor.java:65)
at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74)
... 63 more
form.html
<form method="post" th:object="${grades}" th:action="@{handleSubmit}">
<p style="color:red" th:errors="*{name}"></p>
<input type="text" placeholder="Name" th:field="*{name}">
<input type="text" placeholder="Score" th:field="*{score}">
<p style="color:red" th:errors="*{subject}"></p>
<input type="text" placeholder="Subject" th:field="*{subject}">
<input type="hidden" th:field="*{id}">
<br><br>
<input type="submit" value="Submit">
</form>
Controller
List<Grade> obj=new ArrayList<>();
@GetMapping("/grades")
public String getGrades(Model model){
model.addAttribute("grades",obj);
return "grades";
}
@GetMapping("/")
public String getForm(Model model,@RequestParam(required = false) String id){
int index=getGradeIndex(id);
model.addAttribute("grades",index==Constants.Not_Found?new Grade():obj.get(index));
return "form";
}
@PostMapping("/handleSubmit")
public String submitForm(@Valid Grade grade, BindingResult result){
if(result.hasErrors()){
return "form";
}
int index=getGradeIndex(grade.getId());
if(index==Constants.Not_Found)
obj.add(grade);
else{
obj.set(index, grade);
}
return "redirect:/grades";
}
public Integer getGradeIndex(String id){
for(int i=0;i<obj.size();i++){
if(obj.get(i).getId().equals(id)){
return i;
}
}
return Constants.Not_Found;
}
}
Grade.java
@NotBlank(message="Name cannot be blank")
private String name;
@NotBlank(message="Subject cannot be blank")
private String subject;
private String score;
private String id;
public Grade(){
this.id=UUID.randomUUID().toString();
}
public Grade(String name,String subject,String score){
this.name=name;
this.subject=subject;
this.score=score;
}
