Cannot create BindStatus for valid field on immutable form object in case of bind errors [SPR-16449]

[spring-projects-issues]

Masatoshi Tada opened SPR-16449 and commented

Hi,

I got a problem when using immutable form object.

When a form object is immutable and type conversion failed, a form object became null and an error occurred in a view.
I think this is not convenient. The form object should be created.

Please take a look my sample codes.
(See "Reference URL")

How to reproduce this problem is below.

1. Build this app with mvn package and deploy WAR to Tomcat.
2. Access http://localhost:8080/01-spring/
3. Click [Add new employee].
   !スクリーンショット 2018-02-01 10.56.19.png|thumbnail!
4. Specify "aaaa" in [Joined date] and click [Submit].
   ("Joined date" must be "yyyy-MM-dd")
   !スクリーンショット 2018-02-01 10.56.40.png|thumbnail!
5. View becomes strange.
   !スクリーンショット 2018-02-01 10.56.54.png|thumbnail!
6. Tomcat Localhost Log is below. EmployeeForm is null.

01-Feb-2018 10:56:44.091 ERROR [http-nio-8080-exec-1] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [dispatcher] in context with path [/01-spring] threw exception [Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Error during execution of processor 'org.thymeleaf.spring5.processor.SpringInputGeneralFieldTagProcessor' (template: "employee/insertMain" - line 21, col 53)] with root cause
java.lang.IllegalStateException: Cannot access properties on null bean instance 'employeeForm'!
	at org.springframework.util.Assert.state(Assert.java:73)
	at org.springframework.validation.BeanPropertyBindingResult.createBeanWrapper(BeanPropertyBindingResult.java:111)
	at org.springframework.validation.BeanPropertyBindingResult.getPropertyAccessor(BeanPropertyBindingResult.java:98)
	at org.springframework.validation.AbstractPropertyBindingResult.getActualFieldValue(AbstractPropertyBindingResult.java:103)
	at org.springframework.validation.AbstractBindingResult.getFieldValue(AbstractBindingResult.java:236)
	at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:129)
	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:305)
	at org.thymeleaf.spring5.util.FieldUtils.getBindStatus(FieldUtils.java:252)
	at org.thymeleaf.spring5.util.FieldUtils.getBindStatus(FieldUtils.java:226)
	at org.thymeleaf.spring5.processor.AbstractSpringFieldTagProcessor.doProcess(AbstractSpringFieldTagProcessor.java:174)
	at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74)
	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.handleStandaloneElement(ProcessorTemplateHandler.java:918)
	at org.thymeleaf.engine.StandaloneElementTag.beHandled(StandaloneElementTag.java:228)
	at org.thymeleaf.engine.TemplateModel.process(TemplateModel.java:136)
	at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:592)
	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:355)
	at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:188)
	at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325)
	at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:881)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:855)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:475)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:651)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:500)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:754)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1376)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:745)

Thanks

---

Affects: 5.0.3

Reference URL: https://github.com/MasatoshiTada/spring-for-spring-boot/blob/immutable-form/01-spring/src/main/java/com/example/web/form/EmployeeForm.java

Attachments:

• スクリーンショット 2018-02-01 10.56.19.png (40.87 kB)
• スクリーンショット 2018-02-01 10.56.40.png (21.51 kB)
• スクリーンショット 2018-02-01 10.56.54.png (16.56 kB)

Issue Links:

• BindingResult support for constructor argument mismatch on immutable data object [SPR-15542] #20101 BindingResult support for constructor argument mismatch on immutable data object
• Revisit handling of missing fields (without default values) for immutable data classes [SPR-15877] #20432 Revisit handling of missing fields (without default values) for immutable data classes
• The FieldError class does not provide access to the exception that triggered the binding error. [SPR-16372] #20919 The FieldError class does not provide access to the exception that triggered the binding error.
• Validation failure not exposed next to binding failure for immutable form class [SPR-16841] #21381 Validation failure not exposed next to binding failure for immutable form class

Referenced from: commits 4a1cc9c

[spring-projects-issues]

Juergen Hoeller commented

The immutable form object being null when there was a binding failure is intentional and hard to avoid: We literally cannot construct it if one of its properties is invalid, e.g. in your case when we cannot convert the LocalDateTime and therefore cannot satisfy that constructor argument. The only way around this is to dumb down your constructor to String arguments that can hold any user-given value.

However, it is definitely wrong for BindStatus to fail on creation of the underlying binding result there. We're using a special BindingResult instance during binding, so I suppose we need to fall back to allow for such a null-bound BindingResult here as well... for Thymeleaf but also for any other BindResult-based tag library. I'll have a look at it for 5.0.4 from that perspective.

[spring-projects-issues]

Masatoshi Tada commented

Thank you for fixing quickly! I'm looking forward to 5.0.4😆