[Informa-developer] hibernate lazy initialization PersistenceManager.getGroups

[Scott D. <sc...@sw...>]

Informa 0.6.0
MySQL Connector/J 3.1.8

I've written a very simple application to poll feeds and store them.

There's no problem with creating the persistent channels and persisting
their items using a Poller and PersistenceObserver.

However, when I start my application a 2nd time, I don't want to
recreate the group and channels. 

So, I'm trying to use PersistenceManager.getGroups(). However this
doesn't work.
--------------------------------------------------------
//First, try to get channels from DB.
    try {
      groups = manager.getGroups();     // <-- BLAM! Hibernate exception
here!!!
      for (ChannelGroupIF group: groups) {
        logger.info("Loading channels from group: " +
group.getTitle());// <-- NEVER get to this line.
        Collection<ChannelIF> c = group.getAll();
        channels.addAll(c);
      }
      
      ///If we don't have any chanel groups, build them
      if (groups.length == 0) {
--------------------------------------------------------
The heinous stack trace is below.  I've stepped through the code with a
debugger (using Netbeans 4.1...) and I see that my group is successfully
created, but the exception occurs when trying to get the Collection of
Channels.

I've read the thread on this list about some column's being used to
store serialized object, but I've looked at the ddl and the schema in
MySQL and I don't see any such columns. It looks to me like the "default
null" for the link column in the ITEM table is there, and that in fact
all the rows have NULL value for that column. So, I don't think that's
the problem. 

If anyone knows a way to successfully retrieve Channels from the DB,
please let me know! 

Thanks,

Scott
---------------------------------------------------------------------

(collection.PersistentCollection     198 ) Failed to lazily initialize a
collection
net.sf.hibernate.type.SerializationException: could not deserialize
        at
net.sf.hibernate.util.SerializationHelper.deserialize(SerializationHelper.java:197)
        at
net.sf.hibernate.util.SerializationHelper.deserialize(SerializationHelper.java:220)
        at
net.sf.hibernate.type.SerializableType.fromBytes(SerializableType.java:73)
        at
net.sf.hibernate.type.SerializableType.get(SerializableType.java:38)
        at
net.sf.hibernate.type.NullableType.nullSafeGet(NullableType.java:62)
        at
net.sf.hibernate.type.NullableType.nullSafeGet(NullableType.java:53)
        at
net.sf.hibernate.type.AbstractType.hydrate(AbstractType.java:66)
        at net.sf.hibernate.loader.Loader.hydrate(Loader.java:611)
        at
net.sf.hibernate.loader.Loader.loadFromResultSet(Loader.java:552)
Aug 29, 2005 9:49:15 AM feedcatcher.FeedCatcher2 createChannels
        at
net.sf.hibernate.loader.Loader.instanceNotYetLoaded(Loader.java:511)
        at net.sf.hibernate.loader.Loader.getRow(Loader.java:426)
        at net.sf.hibernate.loader.Loader.doQuery(Loader.java:209)
        at
net.sf.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:133)
        at net.sf.hibernate.loader.Loader.loadEntity(Loader.java:836)
        at net.sf.hibernate.loader.Loader.loadEntity(Loader.java:856)
        at
net.sf.hibernate.loader.EntityLoader.load(EntityLoader.java:59)
        at
net.sf.hibernate.loader.EntityLoader.load(EntityLoader.java:51)
        at
net.sf.hibernate.persister.EntityPersister.load(EntityPersister.java:419)
        at
net.sf.hibernate.impl.SessionImpl.doLoad(SessionImpl.java:2106)
        at
net.sf.hibernate.impl.SessionImpl.doLoadByClass(SessionImpl.java:1980)
        at
net.sf.hibernate.impl.SessionImpl.internalLoad(SessionImpl.java:1942)
        at
net.sf.hibernate.type.ManyToOneType.resolveIdentifier(ManyToOneType.java:68)
        at
net.sf.hibernate.type.EntityType.resolveIdentifier(EntityType.java:232)
SEVERE: Problem getting Channel Group from db!
net.sf.hibernate.LazyInitializationException: Failed to lazily
initialize a collection
        at
net.sf.hibernate.type.EntityType.nullSafeGet(EntityType.java:154)
        at
net.sf.hibernate.collection.AbstractCollectionPersister.readElement(AbstractCollectionPersister.java:363)
        at net.sf.hibernate.collection.Set.readFrom(Set.java:233)
        at
net.sf.hibernate.loader.Loader.readCollectionElement(Loader.java:305)
        at net.sf.hibernate.loader.Loader.doQuery(Loader.java:219)
        at
net.sf.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:133)
        at
net.sf.hibernate.loader.Loader.loadCollection(Loader.java:915)
        at
net.sf.hibernate.loader.Loader.loadCollection(Loader.java:890)
        at
net.sf.hibernate.loader.CollectionLoader.initialize(CollectionLoader.java:83)
        at
net.sf.hibernate.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:284)
        at
net.sf.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:3259)
        at
net.sf.hibernate.collection.PersistentCollection.initialize(PersistentCollection.java:195)
        at
net.sf.hibernate.collection.PersistentCollection.read(PersistentCollection.java:71)
        at net.sf.hibernate.collection.Set.toArray(Set.java:146)
        at
de.nava.informa.utils.manager.hibernate.NonCachingPersistenceManager.initGroupCollections(NonCachingPersistenceManager.java:522)
        at
de.nava.informa.utils.manager.hibernate.NonCachingPersistenceManager.getGroups(NonCachingPersistenceManager.java:504)
        at
de.nava.informa.utils.manager.hibernate.NonCachingPersistenceManager.getGroups(NonCachingPersistenceManager.java:170)
        at
de.nava.informa.utils.manager.hibernate.PersistenceManager.getGroups(PersistenceManager.java:122)
        at feedcatcher.FeedCatcher2.createChannels(FeedCatcher2.java:88)
        at feedcatcher.FeedCatcher2.<init>(FeedCatcher2.java:58)
        at feedcatcher.FeedCatcher2.main(FeedCatcher2.java:79)