Examples of org.hibernate.collection.spi.PersistentCollection

org.hibernate.collection.spi.PersistentCollection
Persistent collections are treated as value objects by Hibernate. ie. they have no independent existence beyond the object holding a reference to them. Unlike instances of entity classes, they are automatically deleted when unreferenced and automatically become persistent when held by a persistent object. Collections can be passed between different objects (change "roles") and this might cause their elements to move from one database table to another.

Hibernate "wraps" a java collection in an instance of PersistentCollection. This mechanism is designed to support tracking of changes to the collection's persistent state and lazy instantiation of collection elements. The downside is that only certain abstract collection types are supported and any extra semantics are lost

Applications should never use classes in this package directly, unless extending the "framework" here.

Changes to structure of the collection are recorded by the collection calling back to the session. Changes to mutable elements (ie. composite elements) are discovered by cloning their state when the collection is initialized and comparing at flush time. @author Gavin King

          //    with the current Session
          //throw new AssertionFailure("bug loading unowned collection");
        }
      }


      PersistentCollection rowCollection = persistenceContext.getLoadContexts()
          .getCollectionLoadContext( rs )
          .getLoadingCollection( persister, collectionRowKey );


      if ( rowCollection != null ) {
        rowCollection.readFrom(
            rs,
            persister,
            descriptor,
            owner );
      }

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          MessageHelper.collectionInfoString( persister.getRole(), key ) );
    }
    final LoadingCollectionEntry loadingCollectionEntry = loadContexts.locateLoadingCollectionEntry( collectionKey );
    if ( loadingCollectionEntry == null ) {
      // look for existing collection as part of the persistence context
      PersistentCollection collection = loadContexts.getPersistenceContext().getCollection( collectionKey );
      if ( collection != null ) {
        if ( collection.wasInitialized() ) {
          LOG.trace( "Collection already initialized; ignoring" );
          // ignore this row of results! Note the early exit
          return null;
        }
        LOG.trace( "Collection not yet initialized; initializing" );
      }
      else {
        final Object owner = loadContexts.getPersistenceContext().getCollectionOwner( key, persister );
        final boolean newlySavedEntity = owner != null
            && loadContexts.getPersistenceContext().getEntry( owner ).getStatus() != Status.LOADING;
        if ( newlySavedEntity ) {
          // important, to account for newly saved entities in query
          // todo : some kind of check for new status...
          LOG.trace( "Owning entity already loaded; ignoring" );
          return null;
        }
        // create one
        LOG.tracev( "Instantiating new collection [key={0}, rs={1}]", key, resultSet );
        collection = persister.getCollectionType().instantiate(
            loadContexts.getPersistenceContext().getSession(), persister, key );
      }
      collection.beforeInitialize( persister, -1 );
      collection.beginRead();
      localLoadingCollectionKeys.add( collectionKey );
      loadContexts.registerLoadingCollectionXRef( collectionKey, new LoadingCollectionEntry( resultSet, persister, key, collection ) );
      return collection;
    }
    if ( loadingCollectionEntry.getResultSet() == resultSet ) {

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    // One thing to be careful of here is a "bare" original collection
    // in which case we should never ever ever reset the dirty flag
    // on the target because we simply do not know...
    if ( original instanceof PersistentCollection ) {
      if ( result instanceof PersistentCollection ) {
        final PersistentCollection originalPersistentCollection = (PersistentCollection) original;
        final PersistentCollection resultPersistentCollection = (PersistentCollection) result;


        preserveSnapshot( originalPersistentCollection, resultPersistentCollection, elemType, owner, copyCache, session );


        if ( ! originalPersistentCollection.isDirty() ) {
          resultPersistentCollection.clearDirty();
        }
      }
    }


    return result;

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    CollectionPersister persister = getPersister( session );
    final PersistenceContext persistenceContext = session.getPersistenceContext();
    final EntityMode entityMode = persister.getOwnerEntityPersister().getEntityMode();


    // check if collection is currently being loaded
    PersistentCollection collection = persistenceContext.getLoadContexts().locateLoadingCollection( persister, key );
    
    if ( collection == null ) {
      
      // check if it is already completely loaded, but unowned
      collection = persistenceContext.useUnownedCollection( new CollectionKey(persister, key, entityMode) );
      
      if ( collection == null ) {
        // create a new collection wrapper, to be initialized later
        collection = instantiate( session, persister, key );
        
        collection.setOwner(owner);
  
        persistenceContext.addUninitializedCollection( persister, collection, key );
  
        // some collections are not lazy:
        if ( initializeImmediately() ) {
          session.initializeCollection( collection, false );
        }
        else if ( !persister.isLazy() ) {
          persistenceContext.addNonLazyCollection( collection );
        }
  
        if ( hasHolder() ) {
          session.getPersistenceContext().addCollectionHolder( collection );
        }
        
      }
      
      if ( LOG.isTraceEnabled() ) {
        LOG.tracef( "Created collection wrapper: %s",
            MessageHelper.collectionInfoString( persister, collection,
                key, session ) );
      }
      
    }
    
    collection.setOwner(owner);


    return collection.getValue();
  }

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          //    with the current Session
          //throw new AssertionFailure("bug loading unowned collection");
        }
      }


      PersistentCollection rowCollection = persistenceContext.getLoadContexts()
          .getCollectionLoadContext( rs )
          .getLoadingCollection( persister, collectionRowKey );


      if ( rowCollection != null ) {
        rowCollection.readFrom( rs, persister, descriptor, owner );
      }


    }
    else if ( optionalKey != null ) {
      // we did not find a collection element in the result set, so we

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          );
        }


        Object collectionOwner = findCollectionOwner( collectionRowKey, resultSet, context );


        PersistentCollection rowCollection = persistenceContext.getLoadContexts()
            .getCollectionLoadContext( resultSet )
            .getLoadingCollection( collectionReference.getCollectionPersister(), collectionRowKey );


        if ( rowCollection != null ) {
          rowCollection.readFrom(
              resultSet,
              collectionReference.getCollectionPersister(),
              aliases.getCollectionColumnAliases(),
              collectionOwner
          );

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      // (if the collection is uninitialized, hibernate has no way of
      // knowing if the collection is actually empty without querying the db)
      getPersister().remove( getKey(), getSession() );
    }
    
    final PersistentCollection collection = getCollection();
    if ( collection != null ) {
      getSession().getPersistenceContext().getCollectionEntry( collection ).afterAction( collection );
    }


    evict();

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  @Override
  public void execute() throws HibernateException {
    final Serializable id = getKey();
    final SessionImplementor session = getSession();
    final CollectionPersister persister = getPersister();
    final PersistentCollection collection = getCollection();
    final boolean affectedByFilters = persister.isAffectedByEnabledFilters( session );


    preUpdate();


    if ( !collection.wasInitialized() ) {
      if ( !collection.hasQueuedOperations() ) {
        throw new AssertionFailure( "no queued adds" );
      }
      //do nothing - we only need to notify the cache... 
    }
    else if ( !affectedByFilters && collection.empty() ) {
      if ( !emptySnapshot ) {
        persister.remove( id, session );
      }
    }
    else if ( collection.needsRecreate( persister ) ) {
      if ( affectedByFilters ) {
        throw new HibernateException(
            "cannot recreate collection while filter is enabled: " +
                MessageHelper.collectionInfoString( persister, collection, id, session )
        );

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  @Override
  public void execute() throws HibernateException {
    // this method is called when a new non-null collection is persisted
    // or when an existing (non-null) collection is moved to a new owner
    final PersistentCollection collection = getCollection();
    
    preRecreate();
    getPersister().recreate( collection, getKey(), getSession() );
    getSession().getPersistenceContext().getCollectionEntry( collection ).afterAction( collection );
    evict();

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          //    with the current Session
          //throw new AssertionFailure("bug loading unowned collection");
        }
      }


      PersistentCollection rowCollection = persistenceContext.getLoadContexts()
          .getCollectionLoadContext( rs )
          .getLoadingCollection( persister, collectionRowKey );


      if ( rowCollection != null ) {
        rowCollection.readFrom( rs, persister, descriptor, owner );
      }


    }
    else if ( optionalKey != null ) {
      // we did not find a collection element in the result set, so we

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Related Classes of org.hibernate.collection.spi.PersistentCollection

com.fasterxml.jackson.datatype.hibernate4.PersistentCollectionSerializer

org.hibernate.action.internal.CollectionRecreateAction

org.hibernate.action.internal.CollectionRemoveAction

org.hibernate.action.internal.CollectionUpdateAction

org.hibernate.action.internal.QueuedOperationCollectionAction

org.hibernate.engine.internal.StatefulPersistenceContext

org.hibernate.engine.loading.internal.CollectionLoadContext

org.hibernate.engine.spi.BatchFetchQueue

org.hibernate.event.internal.AbstractFlushingEventListener

org.hibernate.event.internal.DefaultInitializeCollectionEventListener

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