如何调试Groovy元类添加中的错误？

Question

我有一个grails应用程序在保存期间失败。从域对象保存方法中抛出异常。

是否可以调试并逐步执行元类方法实现？如果没有，调查此类问题的推荐方法是什么？

EDIT 以下是有关我所遇到的具体问题的更多信息：

a different object with the same identifier value was already associated with the session: [package.DomainObject#1]. Stacktrace follows:
Message: a different object with the same identifier value was already associated with the session: [package.DomainObject#1]
    Line | Method
->>  638 | checkUniqueness                 in org.hibernate.engine.StatefulPersistenceContext
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    255 | performSaveOrReplicate          in org.codehaus.groovy.grails.orm.hibernate.support.ClosureEventTriggeringInterceptor
|    203 | performSave . . . . . . . . . . in org.hibernate.event.def.AbstractSaveEventListener
|    129 | saveWithGeneratedId             in     ''
|    210 | saveWithGeneratedOrRequestedId  in org.hibernate.event.def.DefaultSaveOrUpdateEventListener
|    195 | entityIsTransient               in     ''
|    117 | performSaveOrUpdate . . . . . . in     ''
|     93 | onSaveOrUpdate                  in     ''
|    108 | onSaveOrUpdate . . . . . . . .  in org.codehaus.groovy.grails.orm.hibernate.support.ClosureEventTriggeringInterceptor
|    685 | fireSaveOrUpdate                in org.hibernate.impl.SessionImpl
|    677 | saveOrUpdate . . . . . . . . .  in     ''
|    673 | saveOrUpdate                    in     ''
|     58 | doInHibernate . . . . . . . . . in org.codehaus.groovy.grails.orm.hibernate.metaclass.SavePersistentMethod$1
|    406 | doExecute                       in org.springframework.orm.hibernate3.HibernateTemplate
|    339 | execute . . . . . . . . . . . . in     ''
|     56 | performSave                     in org.codehaus.groovy.grails.orm.hibernate.metaclass.SavePersistentMethod
|    215 | doInvokeInternal . . . . . . .  in org.codehaus.groovy.grails.orm.hibernate.metaclass.AbstractSavePersistentMethod
|     63 | invoke                          in org.codehaus.groovy.grails.orm.hibernate.metaclass.AbstractDynamicPersistentMethod
|     -2 | invoke0 . . . . . . . . . . . . in sun.reflect.NativeMethodAccessorImpl
|     57 | invoke                          in     ''
|     43 | invoke . . . . . . . . . . . .  in sun.reflect.DelegatingMethodAccessorImpl
|    601 | invoke                          in java.lang.reflect.Method
|   1243 | jlrMethodInvoke . . . . . . . . in org.springsource.loaded.ri.ReflectiveInterceptor
|    189 | invoke                          in org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoCachedMethodSite
|     53 | call . . . . . . . . . . . . .  in org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite
|     45 | defaultCall                     in org.codehaus.groovy.runtime.callsite.CallSiteArray
|     55 | call . . . . . . . . . . . . .  in org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite
|    124 | call                            in org.codehaus.groovy.runtime.callsite.AbstractCallSite
|    911 | save . . . . . . . . . . . . .  in org.codehaus.groovy.grails.orm.hibernate.HibernateGormInstanceApi
|     -1 | save                            in package.DomainObject

控制器中调用的代码是：

def save() {
  def domainInstance = new DomainObject(params)
  if (!domainInstance.save(flush: true)) {      //<!-- Fails here
    render(view: "create", model: [domainInstance: DomainObject])
    return
  }
  atachUploadedFilesTo(domainInstance)
  flash.message = message(code: 'default.created.message', args: [message(code: 'domainObject.label', default: 'DomainObject'), domainInstance.id])
  redirect(action: "show", id: domainInstance.id)
}

在调用save时，数据库中不存在新实例。它表明在某处保存被调用两次，因此我想调试它。