onreplicatevisitor.cs

NHibernate NET开发者所需的

using NHibernate.Collection;
using NHibernate.Persister.Collection;
using NHibernate.Type;

namespace NHibernate.Event.Default
{
	/// <summary> 
	/// When an entity is passed to replicate(), and there is an existing row, we must
	/// inspect all its collections and
	/// 1. associate any uninitialized PersistentCollections with this session
	/// 2. associate any initialized PersistentCollections with this session, using the existing snapshot
	/// 3. execute a collection removal (SQL DELETE) for each null collection property or "new" collection 
	/// </summary>
	public class OnReplicateVisitor : ReattachVisitor
	{
		private readonly bool isUpdate;

		public OnReplicateVisitor(IEventSource session, object ownerIdentifier, object owner, bool isUpdate)
			: base(session, ownerIdentifier, owner)
		{
			this.isUpdate = isUpdate;
		}

		internal override object ProcessCollection(object collection, CollectionType type)
		{
			if (collection == CollectionType.UnfetchedCollection)
			{
				return null;
			}

			IEventSource session = Session;
			ICollectionPersister persister = session.Factory.GetCollectionPersister(type.Role);

			if (isUpdate)
			{
				RemoveCollection(persister, ExtractCollectionKeyFromOwner(persister), session);
			}
			IPersistentCollection wrapper = collection as IPersistentCollection;
			if (wrapper != null)
			{
				wrapper.SetCurrentSession(session);
				if (wrapper.WasInitialized)
				{
					session.PersistenceContext.AddNewCollection(persister, wrapper);
				}
				else
				{
					ReattachCollection(wrapper, wrapper.CollectionSnapshot);
				}
			}
			else
			{
				// otherwise a null or brand new collection
				// this will also (inefficiently) handle arrays, which
				// have no snapshot, so we can't do any better
				//processArrayOrNewCollection(collection, type);
			}

			return null;
		}
	}
}