Some dirty business is happening in the AMF Servlet...
Im calling a DAO method that is supused to retrieve a list of DTO without any children through a remote object from java to flex:
public List<NivelesPlantillasDto> getList()throws HibernateException{
logger.info("getList()");
List<NivelesPlantillasDto> list = new ArrayList<NivelesPlantillasDto>();
Session session = null;
try{
session = SessionFactory.getInstance().openSession();
list=(List<NivelesPlantillasDto>)session.createQuery("from NivelesPlantillasDto").list();
}catch(HibernateException HE){
logger.info(HE.getMessage(),HE);
if (session!=null && session.isConnected())
session.close();
throw HE;
}
if (session.isConnected())
session.close();
return list;
}
And this is the hbm.xml
<hibernate-mapping>
<class name="architecture.dto.NivelesPlantillasDto" table="nivelesplantillas">
<id name="pkNivelPlantilla" type="int">
<column name="PKNIVELPLANTILLA" />
<generator class="identity" />
</id>
<property name="plantilla" type="java.lang.String">
<column name="PLANTILLA" />
</property>
<set name="habilidadesList" table="habilidades" inverse="true" lazy="true">
<key foreign-key="FKNIVELESPLANTILLAS" not-null="true">
<column name="FKNIVELESPLANTILLAS" sql-type="int"/>
</key>
<one-to-many class="architecture.dto.HabilidadesDto"/>
</set>
<set name="nivelesList" table="niveles" inverse="true" cascade="merge,delete-orphan" order-by="indice" lazy="true">
<key foreign-key="FKNIVELESPLANTILLAS" not-null="true">
<column name="FKNIVELESPLANTILLAS" sql-type="int"/>
</key>
<one-to-many class="architecture.dto.NivelesDto"/>
</set>
<property name="activo" type="boolean">
<column name="ACTIVO" />
</property>
</class>
</hibernate-mapping>
This error comes up after closing the session, because, Hibernate tries to load all the children of this class when the object is being deserialized on the AMF Servlet, I can see the query of every children by leaving the session open. So there are 2 fixes for this error to go away, one is to set lazy="false"
in both one-to-many relations, and the second is leaving the session open until AMF finishes to load all the children, but that's not what I want. Why am I forced to load every child?
Edit: Ok, i just fixed this in an ugly way... I did a clone of the list retrieved, so when this one gets deserialized, it doesn't trigger any Hibernate query. Is there a way to tell LCDS wich collections are being lazy loaded?
Is there a way to tell LCDS wich collections are being lazy loaded?
Not that I know of. I think you should consider implementing the "Open Session in View" pattern - yours is an appropriate use case for that.
Update
Based on the "answer" provided by the OP I'd like to point that there may be a better approach to lazy loading and the size
operation. Hibernate supports extra-lazy collections which only issue a select count(...
statement against the database instead of loading the entire collection if all you need is to get the size of it. Just add this annotation:
@LazyCollection(LazyCollectionOption.EXTRA)
See http://www.frightanic.com/2010/11/21/extra-lazy-one-to-many-mapping-with-hibernate/ for details.