在Spring MVC中，当我从表单提交数据时，会发生异常，如下所示。
情况就像我有Entity类一样，我把另一个实体作为关系的一部分。当我发送数据显示它正常工作但我发布编辑异常后发布数据。我也试过initbinding但是没有用。
org.springframework.beans.NullValueInNestedPathException: Invalid property 'user' of bean class [org.mkcl.iforum.adnan.domain.UsersCredentials]: Value of nested property 'user' is null at org.springframework.beans.BeanWrapperImpl.getNestedBeanWrapper(BeanWrapperImpl.java:453) at org.springframework.beans.BeanWrapperImpl.getBeanWrapperForPropertyPath(BeanWrapperImpl.java:428) at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:645) at org.springframework.beans.AbstractPropertyAccessor.setPropertyValues(AbstractPropertyAccessor.java:78) at org.springframework.validation.DataBinder.applyPropertyValues(DataBinder.java:532) at org.springframework.validation.DataBinder.doBind(DataBinder.java:434) at org.springframework.web.bind.WebDataBinder.doBind(WebDataBinder.java:147) at org.springframework.web.bind.ServletRequestDataBinder.bind(ServletRequestDataBinder.java:108) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter$ArgumentsResolver.resolveArguments(AnnotationMethodHandlerAdapter.java:598) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:242) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:874) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:808) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:476) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:441) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at com.opensymphony.sitemesh.webapp.SiteMeshFilter.obtainContent(SiteMeshFilter.java:129) at com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:77) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:359) at org.springframework.security.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109) at org.springframework.security.intercept.web.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371) at org.springframework.security.ui.ExceptionTranslationFilter.doFilterHttp(ExceptionTranslationFilter.java:101) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371) at org.springframework.security.providers.anonymous.AnonymousProcessingFilter.doFilterHttp(AnonymousProcessingFilter.java:105) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371) at org.springframework.security.ui.rememberme.RememberMeProcessingFilter.doFilterHttp(RememberMeProcessingFilter.java:116) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371) at org.springframework.security.wrapper.SecurityContextHolderAwareRequestFilter.doFilterHttp(SecurityContextHolderAwareRequestFilter.java:91) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371) at org.springframework.security.ui.AbstractProcessingFilter.doFilterHttp(AbstractProcessingFilter.java:268) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371) at org.springframework.security.ui.logout.LogoutFilter.doFilterHttp(LogoutFilter.java:87) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371) at org.springframework.security.ui.SessionFixationProtectionFilter.doFilterHttp(SessionFixationProtectionFilter.java:61) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371) at org.springframework.security.context.HttpSessionContextIntegrationFilter.doFilterHttp(HttpSessionContextIntegrationFilter.java:235) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371) at org.springframework.security.securechannel.ChannelProcessingFilter.doFilterHttp(ChannelProcessingFilter.java:116) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:371) at org.springframework.security.util.FilterChainProxy.doFilter(FilterChainProxy.java:174) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:183) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:138) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at test.HttpsCookieFilter.doFilter(HttpsCookieFilter.java:37) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:525) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:595)