假设您有一个纯POCO对象(例如Customer
),您已在业务层中创建该对象,然后调用context.Add(customer)
。您传入并引用的Customer
对象是否会被更改跟踪?换句话说:您传递的对象是ObjectStateManager
跟踪的同一个对象还是不同的对象?
如果它们不是同一个对象,那么不会导致大量内存消耗,因为有两个对象图一直被维护:一个由业务层中的(开发人员)和另一个由{{ DAL中的1}}
答案 0 :(得分:0)
上下文的理念是不要让它变得太大。甚至有多个具有不同数据视图的上下文。甚至可以使用每个工作单元的新上下文。 所以是的它可以变大。关于这个主题的一些好的阅读 搜索有界上下文和Luw模式。例如来自Julie Lerman。
以下是EF管理的反编译IEntityWrapper(来自EF5.0 / Net 4.0) 将Entity放入ObjectContext时使用IENtityWrapper。
我让你决定它是否很大。
如Millimetric所述,参考是object Entity { get; } // see below inside wrapper
internal interface IEntityWrapper
{
void EnsureCollectionNotNull(RelatedEnd relatedEnd);
EntityKey GetEntityKeyFromEntity();
void AttachContext(ObjectContext context, EntitySet entitySet, MergeOption mergeOption);
void ResetContext(ObjectContext context, EntitySet entitySet, MergeOption mergeOption);
void DetachContext();
void SetChangeTracker(IEntityChangeTracker changeTracker);
void TakeSnapshot(EntityEntry entry);
void TakeSnapshotOfRelationships(EntityEntry entry);
void CollectionAdd(RelatedEnd relatedEnd, object value);
bool CollectionRemove(RelatedEnd relatedEnd, object value);
object GetNavigationPropertyValue(RelatedEnd relatedEnd);
void SetNavigationPropertyValue(RelatedEnd relatedEnd, object value);
void RemoveNavigationPropertyValue(RelatedEnd relatedEnd, object value);
void SetCurrentValue(EntityEntry entry, StateManagerMemberMetadata member, int ordinal, object target, object value);
void UpdateCurrentValueRecord(object value, EntityEntry entry);
RelationshipManager RelationshipManager { get; }
bool OwnsRelationshipManager { get; }
object Entity { get; }
EntityEntry ObjectStateEntry { get; set; }
EntityKey EntityKey { get; set; }
ObjectContext Context { get; set; }
MergeOption MergeOption { get; }
Type IdentityType { get; }
bool InitializingProxyRelatedEnds { get; set; }
bool RequiresRelationshipChangeTracking { get; }
}
/// <summary>
/// Adds an object to the object context.
/// </summary>
/// <param name="entitySetName">Represents the entity set name, which may optionally be qualified by the entity container name. </param><param name="entity">The <see cref="T:System.Object"/> to add.</param><exception cref="T:System.ArgumentNullException">The <paramref name="entity"/> parameter is null. -or-The <paramref name="entitySetName"/> does not qualify.</exception>
public void AddObject(string entitySetName, object entity)
{
EntityUtil.CheckArgumentNull<object>(entity, "entity");
EntityEntry existingEntry;
IEntityWrapper wrappedEntity = EntityWrapperFactory.WrapEntityUsingContextGettingEntry(entity, this, out existingEntry);
if (existingEntry == null)
this.MetadataWorkspace.ImplicitLoadAssemblyForType(wrappedEntity.IdentityType, (Assembly) null);
EntitySet entitySet;
bool isNoOperation;
this.VerifyRootForAdd(false, entitySetName, wrappedEntity, existingEntry, out entitySet, out isNoOperation);
if (isNoOperation)
return;
System.Data.Objects.Internal.TransactionManager transactionManager = this.ObjectStateManager.TransactionManager;
transactionManager.BeginAddTracking();
try
{
RelationshipManager relationshipManager = wrappedEntity.RelationshipManager;
bool flag = true;
try
{
this.AddSingleObject(entitySet, wrappedEntity, "entity");
flag = false;
}
finally
{
if (flag && wrappedEntity.Context == this)
{
EntityEntry entityEntry = this.ObjectStateManager.FindEntityEntry(wrappedEntity.Entity);
if (entityEntry != null && entityEntry.EntityKey.IsTemporary)
{
relationshipManager.NodeVisited = true;
RelationshipManager.RemoveRelatedEntitiesFromObjectStateManager(wrappedEntity);
RelatedEnd.RemoveEntityFromObjectStateManager(wrappedEntity);
}
}
}
relationshipManager.AddRelatedEntitiesToObjectStateManager(false);
}
finally
{
transactionManager.EndAddTracking();
}
}