Question

当我尝试删除具有多对一复合键的对象时，NHibernate会抛出异常。保存对象正常工作。这是一个例外：

[KeyNotFoundException: The given key was not present in the dictionary.]
System.ThrowHelper.ThrowKeyNotFoundException() +28
System.Collections.Generic.Dictionary`2.get_Item(TKey key) +7455516
NHibernate.Engine.StatefulPersistenceContext.RemoveEntity(EntityKey key) in d:\CSharp\NH\nhibernate\src\NHibernate\Engine\StatefulPersistenceContext.cs:434
NHibernate.Action.EntityDeleteAction.Execute() in d:\CSharp\NH\nhibernate\src\NHibernate\Action\EntityDeleteAction.cs:87
NHibernate.Engine.ActionQueue.Execute(IExecutable executable) in d:\CSharp\NH\nhibernate\src\NHibernate\Engine\ActionQueue.cs:136
NHibernate.Engine.ActionQueue.ExecuteActions(IList list) in d:\CSharp\NH\nhibernate\src\NHibernate\Engine\ActionQueue.cs:126
NHibernate.Engine.ActionQueue.ExecuteActions() in d:\CSharp\NH\nhibernate\src\NHibernate\Engine\ActionQueue.cs:174
NHibernate.Event.Default.AbstractFlushingEventListener.PerformExecutions(IEventSource session) in d:\CSharp\NH\nhibernate\src\NHibernate\Event\Default\AbstractFlushingEventListener.cs:241
NHibernate.Event.Default.DefaultFlushEventListener.OnFlush(FlushEvent event) in d:\CSharp\NH\nhibernate\src\NHibernate\Event\Default\DefaultFlushEventListener.cs:19
NHibernate.Impl.SessionImpl.Flush() in d:\CSharp\NH\nhibernate\src\NHibernate\Impl\SessionImpl.cs:1479

以下是我的域名：

public class Order : EntityBase {
    protected Order() {}
    public Order(Guid persistenceId) : base(persistenceId) {
        this.Lines = new List<OrderLine>();
    }
    public virtual int OrderId {get; private set;}
    IList<OrderLine> Lines {get; private set;}
}

public class OrderLine : EntityBase {
    protected OrderLine() {}
    public OrderLine(Guid persistenceId, Order order, int lineId) : base(persistenceId) {
        this.Order = order;
        this.LineId = lineId;
    }
    public virtual Order {get; private set;}
    public virtual LineId {get; private set;}
}

public abstart class EntityBase {
    protected EntityBase() {}
    protected EntityBase(Guid persistenceId) {
        this.PersistenceId = persistenceId;
    }
    public virtual Guid Persistenceid {get; private set;}
    public bool IsTransient {get {return Equals(this.PersistenceId, default(Guid)); }}
    public override bool Equals(object obj) {
        if(ReferenceEquals(null, obj))
            return false;
        if(ReferenceEquals(this, obj))
            return true;
        if(this.GetType() != obj.GetType())
            return false;
        return this.Equals((IEntity)obj);
    }
    public virtual bool Equals(IEntity other) {
        if(ReferenceEquals(null, other))
            return false;
        if(ReferenceEquals(this, other))
            return true;
        if(this.IsTransient || other.IsTransient)
            return false;
        return this.PersistenceId.Equals(other.PersistenceId);
    }
    public override int GetHashCode() {
        return this.IsTransient ? base.GetHashCode() : this.PersistenceId.GetHashCode();
    }
}

这是我的映射文件的样子：

public class OrderClassMap : ClassMap<Order> {
    public OrderClassMap() {
        this.Table("Orders");
        this.Id(x => x.OrderId).Generated.Identity();
        this.Map(x => x.PersistenceId);
        this.HasMany(x => x.Lines).Inverse().KeyColumn("OrderId").Cascade.AllDeleteOrphan();
    }
}

public class OrderLineClassMap : ClassMap<OrderLine> {
    public OrderLineClassMap() {
        this.Table("OrderLines");
        this.CompositeId()
            .KeyReference(x => x.Order, "OrderId")
            .KeyProperty(x => x.LineId);
        this.Map(x => x.PersistenceId);
    }
}

Answer 1

我弄清楚导致错误的原因。我的实体都有一个PersistenceId属性，它是唯一标识每个实体的GUID。在我的基类EntityBase中，我重写了GetHashCode方法并返回基于PersistenceId的哈希码。这对NHibernate来说是错误的，因为我没有提供基于Id NHibernate预期（OrderId）的哈希码。我为所有实体实现了一个新的GetHashCode和Equals方法，删除工作正常。

删除时NHibernate KeyNotFoundException

1 个答案: