使用会话和延迟加载(working with session and lazy loading)

 使用NHibernate和C＃，我遇到了删除加载了属性延迟加载的对象的问题。 
 
 对象是。 
 
public class Item
{
    public virtual Guid ItemID { get; set; }    
    public virtual string Name { get; set; }
    public virtual decimal Price { get; set; }
    public virtual string Image { get; set; }
    public virtual Iesi.Collections.Generic.ISet<Tax> Taxes { get; set; }
}
 
 “Taxes”Collection在这里加载了延迟加载。 所以我需要保持会话开放（据我所知）。 加载“Item”对象时，我使用以下查询。 
 
    public Item FindByID(Guid itemID)
    {
        //using(var session = NHibernateHelper.OpenSession())
        //using (var tr = session.BeginTransaction())
        //{
        //    return session.Get<Item>(itemID);
        //}

        var session = NHibernateHelper.OpenSession();
        return session.Get<Item>(itemID);
    }
 
 在上面的FindByID()代码中，您可以看到我已经注释掉了一些从数据库中提取对象后关闭会话的代码。 这是因为，我需要打开会话，因为我有Taxes对象集合可以被访问懒惰。 打开代码部分显示在返回找到的对象后会话仍处于打开状态。 
 
 当我使用上面加载的对象使用以下代码执行删除时为否。 
 
    public void RemoveItem(Item item)
    {            
        using(var session = NHibernateHelper.OpenSession())
        using (var tr = session.BeginTransaction())
        {
            try
            {
                session.Delete(item);
                tr.Commit();
            }
            catch (Exception Ex)
            {
                throw Ex;
            }
        }
    }
 
 我收到以下错误.. 
 
 
 
 非法尝试将集合与两个打开的会话相关联 
 
 
 错误很明显，获取的对象已打开会话，当我打开另一个会话以删除同一对象时，会产生此错误。 
 
 请有人指导我摆脱这个错误。 谢谢。 

Using NHibernate and C#, I am having an issue with deleting an object that is loaded with attribute lazy loading.
 
The object is.
 
public class Item
{
    public virtual Guid ItemID { get; set; }    
    public virtual string Name { get; set; }
    public virtual decimal Price { get; set; }
    public virtual string Image { get; set; }
    public virtual Iesi.Collections.Generic.ISet<Tax> Taxes { get; set; }
}
 
The "Taxes" Collection is here loaded with lazy loading. So I need to keep session open(As I learnt). When loading the "Item" object I use the following query.
 
    public Item FindByID(Guid itemID)
    {
        //using(var session = NHibernateHelper.OpenSession())
        //using (var tr = session.BeginTransaction())
        //{
        //    return session.Get<Item>(itemID);
        //}

        var session = NHibernateHelper.OpenSession();
        return session.Get<Item>(itemID);
    }
 
In the above code for FindByID() you can see I have commented out some code that is closing the session once the object is fetched from the DB. It was because, I need the session to be open as I have Taxes object collection sould be accessed lazy. The open code section show the session is still open after returning the found object.
 
No when I execute delete using following code with the above loaded object.
 
    public void RemoveItem(Item item)
    {            
        using(var session = NHibernateHelper.OpenSession())
        using (var tr = session.BeginTransaction())
        {
            try
            {
                session.Delete(item);
                tr.Commit();
            }
            catch (Exception Ex)
            {
                throw Ex;
            }
        }
    }
 
I am getting the following error..
 
 
 
Illegal attempt to associate a collection with two open sessions
 
 
The error is clear, The fetched object has opened session, when I open another session for deleting the same object, this error is produced.
 
Please someone guide me to get rid of this error. Thanks.

原文：https://stackoverflow.com/questions/14120300