java - Hibernate - Setting null in entity collection is automatically persisted at transaction commit -

due architecture requirements can't use our hibernate entities dtos, use dozer transform entities pojos.

our typical service looks this:

@transactional(readonly=true) @override public task loadtask(int taskid){     taskentity taske = taskdao.load(taskid);     if (taske != null){         taske.setattachments(null)         task task = objectmapper.convert(taske, task.class);         return task;     }else{         return null;     } } 

as can see, before transforming taskentity task set attachments null. because attachments lazy collection , don't want unnecessarily trigger loading of entities.

before updating spring 4.1.1 worked without problem. however, upgraded spring 3.2.7, leaving hibernate @ 3.6.10. then, when executing same code noticed hibernate executing statement after loadtask execution:

update taskattachment set taskid = null id= ? 

that say, because of setting null in taskentity.attachments, hibernate deletes foreign key in taskattachment.

configuration properties: spring.transactionmanager_class=org.springframework.transaction.jta.websphereuowtransactionmanager hibernate.transaction.manager_lookup_class=org.hibernate.transaction.websphereextendedjtatransactionlookup hibernate.current_session_context_class=jta hibernate.transaction.factory_class=org.hibernate.transaction.jtatransactionfactory jta.usertransaction=java:comp/usertransaction

session factory config

<bean id="mainsessionfactory" class="org.springframework.orm.hibernate3.annotation.annotationsessionfactorybean">     <property name="jtatransactionmanager" ref="jtatransactionmanager" />     <property name="datasource" ref="maindatasource" />     <property name="packagestoscan" ref="packages-mainsessionfactory" />     <property name="hibernateproperties" ref="properties-mainsessionfactory" /> </bean> 

the orm-related thing changed stopped using hibernatetemplate in favour sessionfactory.getcurrentsession().

our former basedao:

public abstract class basedao<entitytype extends baseentity<idtype>, idtype extends serializable> extends hibernatedaosupport      public basedao(hibernatetemplate hibernatetemplate, class<entitytype> clazz){         super();         super.sethibernatetemplate(hibernatetemplate);         this.clazz= clazz;     }      public entitytype load(idtype id){         return gethibernatetemplate().get(clazz, id);     } 

our current basedao:

@suppresswarnings("unchecked") public abstract class basedao<entitytype extends baseentity<idtype>, idtype extends serializable> implements ibasedao<entitytype, idtype>{      private class<entitytype> clazz;      private sessionfactory sessionfactory;      public basedao(sessionfactory sessionfactory, class<entitytype> clazz){         super();         this.clazz= clazz;         this.sessionfactory=sessionfactory;     }         public entitytype load(idtype id){         return (entitytype)getsession().get(clazz, id);     }      protected session getsession(){         return sessionfactory.getcurrentsession();     } 

update: it's not spring version related issue. have checked using hibernatetemplate.get() doesn't persist null, , sessionfactory.getcurrentsession().get() does, why?

@transactional(readonly=true) tells spring operation not modifying db, in such case sets connection read-only , hibernate not update entity. if remove readonly=true see using hibernatetemplate.get() change persisted.

if use sessionfactory.getcurrentsession() you're circumventing spring's initialization part sets session readonly , therefore changes persisted.

relying in readonly=true inhibit updates not practice because not supported dbs , orms. best course of action using session.evict() detach entity. anyway keep readonly=true because if db/orm supports db access optimized read-only operations.