I am using Spring MVC, AJAX/JSON and Hibernate to get all persons from a MySQL database.
I wrote JUnit integration tests to verify my service and all is okay.
Now I call it in this kind:
@RequestMapping(value="/allpersons", method=RequestMethod.GET)
public @ResponseBody Set<Person> getAllPersons() {
Set<Person> persons= new PersonServiceImpl().getAllPersons();
return persons;
}
I debugged it. The line with
return persons;
everything is fine. I have a HashSet with all persons in it.
Debugging more steps, I come to this line:
this.objectMapper.writeValue(jsonGenerator, o);
in
org.springframework.http.converter.json.MappingJacksonHttpMessageConverter
Then I do not see the source code, but my debugger tells me:
StdSerializerProvider._serializeValue(JsonGenerator, Object) line 297
After this line, I get the error:
ERROR: org.hibernate.LazyInitializationException - failed to lazily initialize a collection of role: com.mydomain.project.dom.Person.projects, no session or session was closed
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.mydomain.project.dom.Person.projects, no session or session was closed
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:383)
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:375)
at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:368)
at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:111)
at org.hibernate.collection.PersistentSet.iterator(PersistentSet.java:186)
at org.codehaus.jackson.map.ser.ContainerSerializers$CollectionSerializer.serializeContents(ContainerSerializers.java:339)
at org.codehaus.jackson.map.ser.ContainerSerializers$CollectionSerializer.serializeContents(ContainerSerializers.java:314)
at org.codehaus.jackson.map.ser.ContainerSerializers$AsArraySerializer.serialize(ContainerSerializers.java:112)
at org.codehaus.jackson.map.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:268)
at org.codehaus.jackson.map.ser.BeanSerializer.serializeFields(BeanSerializer.java:160)
at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:131)
at org.codehaus.jackson.map.ser.ContainerSerializers$CollectionSerializer.serializeContents(ContainerSerializers.java:363)
at org.codehaus.jackson.map.ser.ContainerSerializers$CollectionSerializer.serializeContents(ContainerSerializers.java:314)
at org.codehaus.jackson.map.ser.ContainerSerializers$AsArraySerializer.serialize(ContainerSerializers.java:112)
at org.codehaus.jackson.map.ser.StdSerializerProvider._serializeValue(StdSerializerProvider.java:297)
at org.codehaus.jackson.map.ser.StdSerializerProvider.serializeValue(StdSerializerProvider.java:224)
at org.codehaus.jackson.map.ObjectMapper.writeValue(ObjectMapper.java:1030)
at org.springframework.http.converter.json.MappingJacksonHttpMessageConverter.writeInternal(MappingJacksonHttpMessageConverter.java:153)
at org.springframework.http.converter.AbstractHttpMessageConverter.write(AbstractHttpMessageConverter.java:181)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter$ServletHandlerMethodInvoker.writeWithMessageConverters(AnnotationMethodHandlerAdapter.java:975)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter$ServletHandlerMethodInvoker.handleResponseBody(AnnotationMethodHandlerAdapter.java:933)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter$ServletHandlerMethodInvoker.getModelAndView(AnnotationMethodHandlerAdapter.java:882)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:428)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
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 org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java:195)
at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:159)
at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:141)
at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:90)
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:417)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
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.core.StandardHostValve.invoke(StandardHostValve.java:127)
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:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:619)
It seems, that is has something to do with the serialization / JacksonMapping. It wants to get the associated projects of a person, which are not needed and they are normally lazily loaded.
What’s the problem here?
Thank you in advance & Best Regards.
What you encounter is similar with this:
Lazy Loading error
In a nutshell, you are accessing a lazy-loaded collection outside the Hibernate Session.
Possible solutions:
Please check the post specified above for further details.
UPDATE 1
From what I’ve understood, this is caused by the Jackson mapper receiving a model that wasn’t completely loaded (some collections are lazy loaded). You’re saying you don’t need the objects in those collections to be mapped by Jackson. The alternatives I’m seeing are:
Hope this helps.