Hibernate/Domain NullPointerException?

Context: I am trying to upgrade a Grails project from 1.0.3 to 1.3.7 and am running into a bunch of problems. I just was getting a lot of DuplicateMappingExceptions because the project had Hibernate XML files as well as domain files. I moved the domain files out to src/groovy, but now find myself with a new NullPointerException, and I don't know how to go about resolving it:

2011-05-30 10:27:29,037 [main] ERROR context.GrailsContextLoader  - Error executing bootstraps: Error creating bean with name 'messageSource': Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Invocation of init method failed; nested exception is java.lang.NullPointerException
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'messageSource': Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Invocation of init method failed; nested exception is java.lang.NullPointerException
    at org.grails.tomcat.InlineExplodedTomcatServer.doStart(InlineExplodedTomcatServer.groovy:112)
    at org.grails.tomcat.InlineExplodedTomcatServer$doStart.callCurrent(Unknown Source)
    at org.grails.tomcat.TomcatServer.start(TomcatServer.groovy:97)
    at grails.web.container.EmbeddableServer$start.call(Unknown Source)
    at _GrailsRun_groovy$_run_closure5_closure12.doCall(_GrailsRun_groovy:158)
    at _GrailsRun_groovy$_run_closure5_closure12.doCall(_GrailsRun_groovy)
    at _GrailsSettings_groovy$_run_closure10.doCall(_GrailsSettings_groovy:280)
    at _GrailsSettings_groovy$_run_closure10.call(_GrailsSettings_groovy)
    at _GrailsRun_groovy$_run_closure5.doCall(_GrailsRun_groovy:149)
    at _GrailsRun_groovy$_run_closure5.call(_GrailsRun_groovy)
    at _GrailsRun_groovy.runInline(_GrailsRun_groovy:116)
    at _GrailsRun_groovy.this$4$runInline(_GrailsRun_groovy)
    at _GrailsRun_groovy$_run_closure1.doCall(_GrailsRun_groovy:59)
    at RunApp$_run_closure1.doCall(RunApp:33)
    at gant.Gant$_dispatch_closure5.doCall(Gant.groovy:381)
    at gant.Gant$_dispatch_closure7.doCall(Gant.groovy:415)
    at gant.Gant$_dispatch_closure7.doCall(Gant.groovy)
    at gant.Gant.withBuildListeners(Gant.groovy:427)
    at gant.Gant.this$2$withBuildListeners(Gant.groovy)
    at gant.Gant$this$2$withBuildListeners.callCurrent(Unknown Source)
    at gant.Gant.dispatch(Gant.groovy:415)
    at gant.Gant.this$2$dispatch(Gant.groovy)
    at gant.Gant.invokeMethod(Gant.groovy)
    at gant.Gant.executeTargets(Gant.groovy:590)
    at gant.Gant.executeTargets(Gant.groovy:589)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Invocation of init method failed; nested exception is java.lang.NullPointerException
    ... 25 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Invocation of init method failed; nested exception is java.lang.NullPointerException
    ... 25 more
Caused by: java.lang.NullPointerException
    ... 25 more

It looks like the NullPointerException is in:

Caused by: java.lang.NullPointerException
    at org.codehaus.groovy.grails.commons.DefaultGrailsDomainClassProperty.equals(DefaultGrailsDomainClassProperty.java:506)
    at org.codehaus.groovy.grails.commons.GrailsDomainConfigurationUtil.configureDomainClassRelationships(GrailsDomainConfigurationUtil.java:167)
    at org.codehaus.groovy.grails.commons.DomainClassArtefactHandler.initialize(DomainClassArtefactHandler.java:67)
    at org.codehaus.groovy.grails.commons.DefaultGrailsApplication.initializeArtefacts(DefaultGrailsApplication.java:738)
    at org.codehaus.groovy.grails.commons.DefaultGrailsApplication.initializeArtefacts(DefaultGrailsApplication.java:721)
    at org.codehaus.groovy.grails.commons.DefaultGrailsApplication.addArtefact(DefaultGrailsApplication.java:682)
    at org.codehaus.groovy.grails.orm.hibernate.cfg.GrailsHibernateUtil.configureDomainClass(GrailsHibernateUtil.java:163)
    at org.codehaus.groovy.grails.orm.hibernate.cfg.GrailsHibernateUtil.configureHibernateDomainClasses(GrailsHibernateUtil.java:117)
    at org.codehaus.groovy.grails.orm.hibernate.cfg.GrailsAnnotationConfiguration.buildSessionFactory(GrailsAnnotationConfiguration.java:124)
    at org.springframework.orm.hibernate3.LocalSessionFactoryBean.newSessionFactory(LocalSessionFactoryBean.java:860)
    at org.codehaus.groovy.grails.orm.hibernate.ConfigurableLocalSessionFactoryBean.newSessionFactory(ConfigurableLocalSessionFactoryBean.java:126)
    at org.springframework.orm.hibernate3.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:779)
    at org.springframework.orm.hibernate3.AbstractSessionFactoryBean.afterPropertiesSet(AbstractSessionFactoryBean.java:211)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1477)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1417)
    ... 461 more

This makes it seem like the error is in the Domain Classes (either the classes themselves or the Hibernate XML) that I just moved to src/groovy. I have both domain classes and hibernate xml in the project.

Here are a couple of links that I have found that show a similar stack trace. It definitely seems like something funky in开发者_如何学运维 the relationship between the Hibernate XML and the Domain Classes:

• Similar Stack Trace 1
• Similar Stack Trace 2

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Looks like you shouldn't use Hibernate mapping on non-domain classes. The exception says that there's a relationship configured that Grails can't find a target property for (see here, line 167). Namely, there's a null in some class' persistentProperties.

I have a very little idea why that bug occurs, but would start with moving all mapped classes to domain, then remove all XML mappings, then start running the app on HQL and adding XML configs back one-by-one. This would narrow the search pretty quickly.

You can also give a shot to debugging Grails itself - the source is available.

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Tough to diagnose this, since the stack trace doesn't really have any useful info. I would try increasing the logging to see if that gives any clues, and then start to disable plugins one by one to see if it gets you further.