Hi,

I have a bidirectional many-to-many mapping.

On one side collection of entities A is mapped to entity B collection.
I am using <set> mapping in my hbm.xml because I don't need indexed column.

I sort the order of entites A by using order-by attribute, and it is crucial that the order is perserved.

Can I use <set> in my mapping file, and java.util.List in my java class?

MB

I believe so. Someone else please correct me if I am wrong. You can do a simple check.

Hi, thanks for reply.

Actually I couldn't (yet at least).
The exception is:
java.lang.ClassCastException: java.util.ArrayList
at org.hibernate.type.SetType.wrap(Lorg/hibernate/engine/SessionImplementor;Ljava/lang/Object;)Lorg/hibernate/collection/PersistentCollection;(SetType.java:36)
at org.hibernate.event.def.WrapVisitor.processArrayOrNewCollection(Ljava/lang/Object;Lorg/hibernate/type/CollectionType;)Ljava/lang/Object;(WrapVisitor.java:83)
at org.hibernate.event.def.WrapVisitor.processCollection(Ljava/lang/Object;Lorg/hibernate/type/CollectionType;)Ljava/lang/Object;(WrapVisitor.java:50)
at org.hibernate.event.def.AbstractVisitor.processValue(Ljava/lang/Object;Lorg/hibernate/type/Type;)Ljava/lang/Object;(AbstractVisitor.java:104)
at org.hibernate.event.def.WrapVisitor.processValue(I[Ljava/lang/Object;[Lorg/hibernate/type/Type;)V(WrapVisitor.java:97)
at org.hibernate.event.def.AbstractVisitor.processEntityPropertyValues([Ljava/lang/Object;[Lorg/hibernate/type/Type;)V(AbstractVisitor.java:58)
at org.hibernate.event.def.AbstractSaveEventListener.visitCollectionsBeforeSave(Ljava/io/Serializable;[Ljava/lang/Object;[Lorg/hibernate/type/Type;Lorg/hibernate/engine/SessionImplementor;)Z(AbstractSaveEventListener.java:281)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(Ljava/lang/Object;Ljava/io/Serializable;Lorg/hibernate/persister/entity/EntityPersister;ZLjava/lang/Object;Lorg/hibernate/engine/SessionImplementor;)Ljava/io/Serializable;(AbstractSaveEventListener.java:222)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(Ljava/lang/Object;Ljava/io/Serializable;Lorg/hibernate/persister/entity/EntityPersister;ZLjava/lang/Object;Lorg/hibernate/engine/SessionImplementor;)Ljava/io/Serializable;(AbstractSaveEventListener.java:160)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(Ljava/lang/Object;Ljava/lang/String;Ljava/lang/Object;Lorg/hibernate/engine/SessionImplementor;)Ljava/io/Serializable;(AbstractSaveEventListener.java:95)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(Lorg/hibernate/event/SaveOrUpdateEvent;)Ljava/io/Serializable;(DefaultSaveOrUpdateEventListener.java:184)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(Lorg/hibernate/event/SaveOrUpdateEvent;)Ljava/io/Serializable;(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(Lorg/hibernate/event/SaveOrUpdateEvent;)Ljava/io/Serializable;(DefaultSaveOrUpdateEventListener.java:173)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(Lorg/hibernate/event/SaveOrUpdateEvent;)Ljava/io/Serializable;(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(Lorg/hibernate/event/SaveOrUpdateEvent;)Ljava/io/Serializable;(DefaultSaveOrUpdateEventListener.java:69)
at org.hibernate.impl.SessionImpl.save(Ljava/lang/String;Ljava/lang/Object;)Ljava/io/Serializable;(SessionImpl.java:481)
at org.hibernate.impl.SessionImpl.save(Ljava/lang/Object;)Ljava/io/Serializable;(SessionImpl.java:476)

Any ideas?

Thanks

MB

The explanation might be in the Hibernate reference, p 87, paragraph starting "If your table doesn't have an index column, and you still wish to use List as the property type..."

However, from your description, I don't see why you need Hibernate to know about the association at all. Your way of preserving the order by an order-by indicates that you always read the collection elements using an SQL statement you wrote yourself. Letting Hibernate fetch the associated elements wouldn't use your order-by clause, so your ordering wouldn't be preserved.

i must be blind :)