为什么NHibernate会抛出一个;GenericADOException:无法初始化集合";ISession期间出现异常。在这种情况下是否刷新?
我在为什么NHibernate会抛出一个;GenericADOException:无法初始化集合";ISession期间出现异常。在这种情况下是否刷新?,nhibernate,nhibernate-mapping,lazy-loading,Nhibernate,Nhibernate Mapping,Lazy Loading,我在ISession.Refresh() 我有一个具有延迟加载的子集合的实体,以及一个命中此集合的只读属性,所有这些都包含在二级缓存中。 我在长会话中使用ISession.Refresh(),在将事务提交到DB后获取最新数据,并得到以下错误: NHibernate.Exceptions.GenericADOException : could not initialize a collection: [Test.NUnit.DBTest.TestModel.ParentTestEntity.Chi
ISession.Refresh()
我有一个具有延迟加载的子集合的实体,以及一个命中此集合的只读属性,所有这些都包含在二级缓存中。
我在长会话中使用ISession.Refresh()
,在将事务提交到DB后获取最新数据,并得到以下错误:
NHibernate.Exceptions.GenericADOException : could not initialize a collection: [Test.NUnit.DBTest.TestModel.ParentTestEntity.Children#d4251363-cf88-4684-b65a-9f330107afcf][SQL: SELECT children0_.ParentTestEntity_id as ParentTe4_1_, children0_.Id as Id1_, children0_.Id as Id42_0_, children0_.RowVersion as RowVersion42_0_, children0_.Parent_id as Parent3_42_0_ FROM "ChildTestEntity" children0_ WHERE children0_.ParentTestEntity_id=?]
----> System.NullReferenceException : Object reference not set to an instance of an object.
at NHibernate.Loader.Loader.LoadCollection(ISessionImplementor session, Object id, IType type)
at NHibernate.Loader.Collection.CollectionLoader.Initialize(Object id, ISessionImplementor session)
at NHibernate.Persister.Collection.AbstractCollectionPersister.Initialize(Object key, ISessionImplementor session)
at NHibernate.Event.Default.DefaultInitializeCollectionEventListener.OnInitializeCollection(InitializeCollectionEvent event)
at NHibernate.Impl.SessionImpl.InitializeCollection(IPersistentCollection collection, Boolean writing)
at NHibernate.Collection.AbstractPersistentCollection.Initialize(Boolean writing)
at NHibernate.Collection.AbstractPersistentCollection.ReadSize()
at NHibernate.Collection.PersistentBag.get_Count()
DBTest\TestModel\EntiteTestCacheCollectionsParent.cs(25,0): at Test.NUnit.DBTest.TestModel.ParentTestEntity.get_Count()
at (Object , GetterCallback )
at NHibernate.Bytecode.Lightweight.AccessOptimizer.GetPropertyValues(Object target)
at NHibernate.Tuple.Entity.PocoEntityTuplizer.GetPropertyValuesWithOptimizer(Object entity)
at NHibernate.Tuple.Entity.PocoEntityTuplizer.GetPropertyValues(Object entity)
at NHibernate.Persister.Entity.AbstractEntityPersister.GetPropertyValues(Object obj, EntityMode entityMode)
at NHibernate.Event.Default.AbstractVisitor.Process(Object obj, IEntityPersister persister)
at NHibernate.Event.Default.DefaultRefreshEventListener.OnRefresh(RefreshEvent event, IDictionary refreshedAlready)
at NHibernate.Event.Default.DefaultRefreshEventListener.OnRefresh(RefreshEvent event)
at NHibernate.Impl.SessionImpl.FireRefresh(RefreshEvent refreshEvent)
at NHibernate.Impl.SessionImpl.Refresh(Object obj)
DBTest\NHibernateBehaviorTests.cs(610,0): at Test.NUnit.DBTest.NHibernateBehaviorTests.Test()
--NullReferenceException
at NHibernate.Engine.Loading.CollectionLoadContext.AddCollectionToCache(LoadingCollectionEntry lce, ICollectionPersister persister)
at NHibernate.Engine.Loading.CollectionLoadContext.EndLoadingCollection(LoadingCollectionEntry lce, ICollectionPersister persister)
at NHibernate.Engine.Loading.CollectionLoadContext.EndLoadingCollections(ICollectionPersister persister, IList`1 matchedCollectionEntries)
at NHibernate.Engine.Loading.CollectionLoadContext.EndLoadingCollections(ICollectionPersister persister)
at NHibernate.Loader.Loader.EndCollectionLoad(Object resultSetId, ISessionImplementor session, ICollectionPersister collectionPersister)
at NHibernate.Loader.Loader.InitializeEntitiesAndCollections(IList hydratedObjects, Object resultSetId, ISessionImplementor session, Boolean readOnly)
at NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies)
at NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies)
at NHibernate.Loader.Loader.LoadCollection(ISessionImplementor session, Object id, IType type)
下面是一个单元测试,它显示了简化模型的问题:
[Test]
public void Test()
{
ISession session1 = NHibernateHelper.SessionFactory.OpenSession();
ISession session2 = NHibernateHelper.SessionFactory.OpenSession();
// Create a new entity tree and persist it
ParentTestEntity parentSession1 = new ParentTestEntity();
parentSession1.AddChild(new ChildTestEntity());
session1.Save(parentSession1);
session1.Flush();
// Load the saved object into another session
ParentTestEntity parentSession2 = session2.Get<ParentTestEntity>(parentSession1.Id);
session2.Refresh(parentSession2); // Throws here
}
[测试]
公开无效测试()
{
ISession session1=NHibernateHelper.SessionFactory.OpenSession();
ISession session2=NHibernateHelper.SessionFactory.OpenSession();
//创建一个新的实体树并将其持久化
ParentTestEntity parentSession1=新的ParentTestEntity();
parentSession1.AddChild(newChildTestEntity());
session1.Save(parentSession1);
session1.Flush();
//将保存的对象加载到另一个会话中
ParentTestEntity parentSession2=session2.Get(parentSession1.Id);
session2.Refresh(parentSession2);//在此处抛出
}
以下是涉及的实体:
public class ParentTestEntity
{
public virtual Guid Id { get; private set; }
public virtual long RowVersion { get; private set; }
public virtual IList<ChildTestEntity> Children { get; protected set; }
public ParentTestEntity()
{
this.Children = new List<ChildTestEntity>();
}
public virtual int Count
{
get
{
return Children.Count;
}
set { }
}
public virtual void AddChild(ChildTestEntity child)
{
if (this.Children == null)
{
this.Children = new List<ChildTestEntity>();
}
this.Children.Add(child);
child.Parent = this;
}
}
public class ChildTestEntity
{
public virtual Guid Id { get; private set; }
public virtual long RowVersion { get; private set; }
public virtual ParentTestEntity Parent { get; set; }
}
公共类ParentTestEntity
{
公共虚拟Guid Id{get;private set;}
公共虚拟长行版本{get;private set;}
公共虚拟IList子项{get;protected set;}
公共ParentTestEntity()
{
this.Children=新列表();
}
公共虚拟整数计数
{
得到
{
返回儿童。计数;
}
集合{}
}
公共虚拟void AddChild(ChildTestEntity子项)
{
if(this.Children==null)
{
this.Children=新列表();
}
this.Children.Add(child);
child.Parent=this;
}
}
公营儿童福利机构
{
公共虚拟Guid Id{get;private set;}
公共虚拟长行版本{get;private set;}
公共虚拟ParentTestEntity父项{get;set;}
}
及其映射:
public class ParentTestEntityMap : ClassMap<ParentTestEntity>
{
public ParentTestEntityMap()
{
Cache.ReadWrite();
Id(x => x.Id)
.GeneratedBy.GuidComb();
Version(x => x.RowVersion);
HasMany(x => x.Children)
.Inverse()
.Cascade.All()
.Cache.ReadWrite();
Map(x => x.Count);
}
}
public class ChildTestEntityMap : ClassMap<ChildTestEntity>
{
public ChildTestEntityMap()
{
Cache.ReadWrite();
Id(x => x.Id)
.GeneratedBy.GuidComb();
Version(x => x.RowVersion);
References(x => x.Parent)
.Not.Nullable();
}
}
公共类ParentTestEntityMap:ClassMap
{
公共ParentTestEntityMap()
{
Cache.ReadWrite();
Id(x=>x.Id)
.GeneratedBy.GuidComb();
版本(x=>x.RowVersion);
有很多(x=>x个孩子)
.Inverse()
.Cascade.All()
.Cache.ReadWrite();
Map(x=>x.Count);
}
}
公共类ChildTestEntityMap:ClassMap
{
公共儿童测试地图()
{
Cache.ReadWrite();
Id(x=>x.Id)
.GeneratedBy.GuidComb();
版本(x=>x.RowVersion);
引用(x=>x.Parent)
.Not.Nullable();
}
}
在我的测试中,我发现:
- 正在删除
属性的映射Count
- 正在删除
映射缓存.ReadWrite()
- 在刷新之前枚举集合
刷新
正常工作
有人知道我能做些什么来更新工作吗
注:
- 我可以在NHibernate 2.1.2和3.1.0中重现这种行为
- 我知道
中的空setter很难看,它在这里只是为了反映真实模型中实体的映射Count
- 请参阅。我不会在这里详述所有细节,因为你可以在那里阅读
简单的回答是,您正在访问构造函数中的虚拟属性,这是不允许的。下面的更改应该可以解决这个问题。更换这些线路
public virtual IList<ChildTestEntity> Children { get; protected set; }
public ParentTestEntity()
{
this.Children = new List<ChildTestEntity>();
}
public虚拟IList子项{get;protected set;}
公共ParentTestEntity()
{
this.Children=新列表();
}
。。。以下几行:
private IList<ChildTestEntity> _children;
public virtual IList<ChildTestEntity> Children
{
get { return _children; }
protected set { _children = value; }
}
public ParentTestEntity()
{
_children = new List<ChildTestEntity>();
}
private IList\u儿童;
公共虚拟现实主义儿童
{
获取{return\u children;}
受保护集{u children=value;}
}
公共ParentTestEntity()
{
_children=新列表();
}
FxCop和ReSharper是两种不同的工具,可以自动识别此问题。使用Load()
替换Get()
cirucmv解决此问题
这不是一个通用的解决方案,因为Load()
的语义稍有不同,如果对应的行不存在,就会抛出
不过,这在我们的体系结构中是一个可接受的约束,因为我们知道加载的实体存在于数据库中
但是,仍然欢迎使用
Get()
的任何解决方案。没错,这是模型中一个糟糕的设计疏忽(我知道规则,但当时没有想到,谢谢提醒我)。然而,这与问题无关;测试失败的方式与您的更改完全相同。它似乎更多地与计数的getter相关联,如堆栈跟踪所示。