Table of Contents
Overview
I woke up on Saturday morning expecting a normal day where I worked on my side project ukata.io. However, life is unexpected. I opened one of my content on the *production* site and found an error in the front end. None of my courses are accessible!
This is the log in the backend:
2023-08-26T03:16:28.475Z ERROR 1 --- [nio-8788-exec-1] i.u.a.c.h.error.ExceptionHandlingAdvice : [traceId: rt-b09bb725-18c2-4933-a616-0ea9f916adb4] Failed to instantiate io.ukata.api.courses.models.lesson.ContentItem using constructor NO_CONSTRUCTOR with arguments org.springframework.data.mapping.model.MappingInstantiationException: Failed to instantiate io.ukata.api.courses.models.lesson.ContentItem using constructor NO_CONSTRUCTOR with arguments at org.springframework.data.mapping.model.ReflectionEntityInstantiator.instantiateClass(ReflectionEntityInstantiator.java:102) ~[spring-data-commons-3.0.1.jar:3.0.1] at org.springframework.data.mapping.model.ReflectionEntityInstantiator.createInstance(ReflectionEntityInstantiator.java:53) ~[spring-data-commons-3.0.1.jar:3.0.1] at org.springframework.data.mapping.model.ClassGeneratingEntityInstantiator.createInstance(ClassGeneratingEntityInstantiator.java:98) ~[spring-data-commons-3.0.1.jar:3.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:509) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readDocument(MappingMongoConverter.java:477) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter$DefaultConversionContext.convert(MappingMongoConverter.java:2325) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter$ConversionContext.convert(MappingMongoConverter.java:2131) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readCollectionOrArray(MappingMongoConverter.java:1402) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter$DefaultConversionContext.convert(MappingMongoConverter.java:2297) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter$ConversionContext.convert(MappingMongoConverter.java:2131) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter$MongoDbPropertyValueProvider.getPropertyValue(MappingMongoConverter.java:1900) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readProperties(MappingMongoConverter.java:624) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.populateProperties(MappingMongoConverter.java:535) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:513) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readDocument(MappingMongoConverter.java:477) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter$DefaultConversionContext.convert(MappingMongoConverter.java:2325) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter$ConversionContext.convert(MappingMongoConverter.java:2131) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readCollectionOrArray(MappingMongoConverter.java:1402) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter$DefaultConversionContext.convert(MappingMongoConverter.java:2297) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter$ConversionContext.convert(MappingMongoConverter.java:2131) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter$MongoDbPropertyValueProvider.getPropertyValue(MappingMongoConverter.java:1900) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readProperties(MappingMongoConverter.java:624) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.populateProperties(MappingMongoConverter.java:535) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:513) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readDocument(MappingMongoConverter.java:477) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:413) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.convert.MappingMongoConverter.project(MappingMongoConverter.java:305) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.MongoTemplate$ProjectingReadCallback.doWith(MongoTemplate.java:3123) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.MongoTemplate.executeFindMultiInternal(MongoTemplate.java:2735) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.MongoTemplate.doFind(MongoTemplate.java:2470) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.ExecutableFindOperationSupport$ExecutableFindSupport.doFind(ExecutableFindOperationSupport.java:171) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.core.ExecutableFindOperationSupport$ExecutableFindSupport.oneValue(ExecutableFindOperationSupport.java:111) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.repository.query.AbstractMongoQuery.lambda$getExecution$6(AbstractMongoQuery.java:179) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.repository.query.AbstractMongoQuery.doExecute(AbstractMongoQuery.java:143) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.mongodb.repository.query.AbstractMongoQuery.execute(AbstractMongoQuery.java:118) ~[spring-data-mongodb-4.0.1.jar:4.0.1] at org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:136) ~[spring-data-commons-3.0.1.jar:3.0.1] at org.springframework.data.repository.core.support.RepositoryMethodInvoker.invoke(RepositoryMethodInvoker.java:120) ~[spring-data-commons-3.0.1.jar:3.0.1] at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:164) ~[spring-data-commons-3.0.1.jar:3.0.1] at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:143) ~[spring-data-commons-3.0.1.jar:3.0.1] at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184) ~[spring-aop-6.0.4.jar:6.0.4] at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:77) ~[spring-data-commons-3.0.1.jar:3.0.1] at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184) ~[spring-aop-6.0.4.jar:6.0.4] at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97) ~[spring-aop-6.0.4.jar:6.0.4] at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184) ~[spring-aop-6.0.4.jar:6.0.4] at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:218) ~[spring-aop-6.0.4.jar:6.0.4] at jdk.proxy2/jdk.proxy2.$Proxy150.findByCourseIdAndId(Unknown Source) ~[na:na] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:na] at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:na] at java.base/java.lang.reflect.Method.invoke(Unknown Source) ~[na:na] at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343) ~[spring-aop-6.0.4.jar:6.0.4] at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:196) ~[spring-aop-6.0.4.jar:6.0.4] at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-6.0.4.jar:6.0.4] at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137) ~[spring-tx-6.0.4.jar:6.0.4] at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184) ~[spring-aop-6.0.4.jar:6.0.4] at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:218) ~[spring-aop-6.0.4.jar:6.0.4] at jdk.proxy2/jdk.proxy2.$Proxy150.findByCourseIdAndId(Unknown Source) ~[na:na] at io.ukata.api.core.services.helpers.TakerService.getLesson(TakerService.java:771) ~[classes/:0.0.1] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:na] at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:na] at java.base/java.lang.reflect.Method.invoke(Unknown Source) ~[na:na] at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343) ~[spring-aop-6.0.4.jar:6.0.4] at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:699) ~[spring-aop-6.0.4.jar:6.0.4] at io.ukata.api.core.services.helpers.TakerService$$SpringCGLIB$$0.getLesson(<generated>) ~[classes/:0.0.1] at io.ukata.api.courses.controllers.taker.CourseTakerController.getLesson(CourseTakerController.java:60) ~[classes/:0.0.1] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:na] at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:na] at java.base/java.lang.reflect.Method.invoke(Unknown Source) ~[na:na] at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:207) ~[spring-web-6.0.4.jar:6.0.4] at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:152) ~[spring-web-6.0.4.jar:6.0.4] at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-6.0.4.jar:6.0.4] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:884) ~[spring-webmvc-6.0.4.jar:6.0.4] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) ~[spring-webmvc-6.0.4.jar:6.0.4] at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-6.0.4.jar:6.0.4] at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1080) ~[spring-webmvc-6.0.4.jar:6.0.4] at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:973) ~[spring-webmvc-6.0.4.jar:6.0.4] at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1011) ~[spring-webmvc-6.0.4.jar:6.0.4] at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:903) ~[spring-webmvc-6.0.4.jar:6.0.4] at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:705) ~[tomcat-embed-core-10.1.5.jar:6.0] at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885) ~[spring-webmvc-6.0.4.jar:6.0.4] at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:814) ~[tomcat-embed-core-10.1.5.jar:6.0] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:223) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-10.1.5.jar:10.1.5] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.springframework.security.web.FilterChainProxy.lambda$doFilterInternal$3(FilterChainProxy.java:231) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:365) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.access.intercept.AuthorizationFilter.doFilter(AuthorizationFilter.java:100) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:126) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:120) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:131) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:85) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:100) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:179) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.oauth2.server.resource.web.authentication.BearerTokenAuthenticationFilter.doFilterInternal(BearerTokenAuthenticationFilter.java:145) ~[spring-security-oauth2-resource-server-6.0.1.jar:6.0.1] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.0.4.jar:6.0.4] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:107) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:93) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.0.4.jar:6.0.4] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.context.SecurityContextHolderFilter.doFilter(SecurityContextHolderFilter.java:82) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.context.SecurityContextHolderFilter.doFilter(SecurityContextHolderFilter.java:69) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:62) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.0.4.jar:6.0.4] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.session.DisableEncodeUrlFilter.doFilterInternal(DisableEncodeUrlFilter.java:42) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.0.4.jar:6.0.4] at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:233) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:191) ~[spring-security-web-6.0.1.jar:6.0.1] at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:351) ~[spring-web-6.0.4.jar:6.0.4] at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:267) ~[spring-web-6.0.4.jar:6.0.4] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-6.0.4.jar:6.0.4] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.0.4.jar:6.0.4] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-6.0.4.jar:6.0.4] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.0.4.jar:6.0.4] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-6.0.4.jar:6.0.4] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.0.4.jar:6.0.4] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:177) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:119) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:400) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:859) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1734) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-10.1.5.jar:10.1.5] at java.base/java.lang.Thread.run(Unknown Source) ~[na:na] Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [io.ukata.api.courses.models.lesson.ContentItem]: Specified class is an interface at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:137) ~[spring-beans-6.0.4.jar:6.0.4] at org.springframework.data.mapping.model.ReflectionEntityInstantiator.instantiateClass(ReflectionEntityInstantiator.java:99) ~[spring-data-commons-3.0.1.jar:3.0.1] ... 156 common frames omitted
I’m no expert but from the log, there seemed to be something wrong with MongoDB mapping.
I tried creating a few content on my local development, no errors!
Reading the log further and also spending the morning on StackOverflow, I finally found the cause and the fix!
The cause
The problem was I, as a novice developer, changed the class name (that I persisted into MongoDB) a few weeks ago.
If you are familiar with the way Spring Data MongoDB store documents in the database, you’d probably know that the documents have a “_class” field. That helps the process of reading data from MongoDB and convert to your Java Beans.
I naively changed the class name from “LessonRichText” to “ContentRichText”. This made spring data MongoDB freaked out. It didn’t know how to deserialize the json document back to java objects.
The fix
The fix was obviously to update the value of the class fields. However, updating manually would be a daunting task.
I’m not a MongoDB expert either.
In addition, the field I need to update is not in the root document. The root document contains a collection called “steps”. Each step contains a collection of “items”.
I need to update the _class field of each Item.
This is where I found out about writing a javascript function in MongoDB shell, which is super cool.
Here is how I managed to update all the documents with just a command line query:
db.course_lessons.find({"steps.items._class": "io.ukata.api.courses.models.lesson.LessonMedia"}).forEach((doc) => {
if (doc.steps && doc.steps.length > 0) {
doc.steps.forEach((step) => {
if (step.items && step.items.length > 0) {
step.items.forEach(item => {
if (item._class === 'io.ukata.api.courses.models.lesson.LessonMedia') {
item._class = 'io.ukata.api.courses.models.lesson.ContentMedia';
}
});
}
})
}
db.course_lessons.replaceOne({"_id": doc._id}, doc);
});You’d probably know what the code does. First, it tried to find the documents that have steps.items._class that were mapped to the old class name. Next it looped through the arrays and updated the value.
That’s a O(n3) but I didn’t care. In production, anything is permissible when it comes to fixing bugs!
Take away
The takeaway from my mistake is: Be very careful when you update class names, packages of classes that you persist into databases.
I build softwares that solve problems. I also love writing/documenting things I learn/want to learn.