Fix Failed to instantiate... using constructor NO_CONSTRUCTOR with arguments

Table of Contents

1 Overview
2 The cause
3 The fix
4 Take away

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.

Đạt Trần

I build softwares that solve problems. I also love writing/documenting things I learn/want to learn.

Fix Failed to instantiate… using constructor NO_CONSTRUCTOR with arguments

Overview

The cause

The fix

Take away

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