Question

我有一些非规范化数据用于性能原因，我试图用NHibernate事件监听器而不是触发器来维护数据。我不相信这是最好的方法，但我深入研究它，我想在继续前进之前想出来。我收到了以下错误：

System.InvalidOperationException : Collection was modified; enumeration operation may not execute. 
    System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource) 
    System.Collections.Generic.List`1.Enumerator.MoveNextRare() 
    System.Collections.Generic.List`1.Enumerator.MoveNext() 
    NHibernate.Engine.ActionQueue.ExecuteActions(IList list) 
    NHibernate.Engine.ActionQueue.ExecuteActions() 
NHibernate.Event.Default.AbstractFlushingEventListener.PerformExecutions (IEventSource session) 
    NHibernate.Event.Default.DefaultFlushEventListener.OnFlush(FlushEvent event) 
    NHibernate.Impl.SessionImpl.Flush() 
    NHibernate.Transaction.AdoTransaction.Commit()

以下是要实现的代码：

using (var tx = session.BeginTransaction()) 
{ 
    var business = session 
        .Get<Business>(1234) 
        .ChangeZipCodeTo("92011"); 
    session.Update(business); 
    tx.Commit(); // error happens here 
}

和事件监听器：

public void OnPostUpdate(PostUpdateEvent @event) 
{ 
    var business = @event.Entity as Business; 
    if (business != null) 
    { 
        var links = @event.Session 
            .CreateQuery("select l from BusinessCategoryLink as l where l.Business.BusinessId = :businessId") 
            .SetParameter("businessId", business.BusinessId) 
            .List<BusinessCategoryLink>();

        foreach (var link in links) 
        { 
            link.Location = business.Location; 
            @event.Session.Update(link); 
        } 
    } 
}

Answer 1

这看起来与NHibernate无关，而是C＃处理迭代器的方式，特别是Enumerations。我有点猜测，但我认为这是因为你在这一行修改了枚举的值：link.Location = business.Location;。快速谷歌搜索告诉我Enumerator.Current属性是只读的（这是使用foreach构造时使用的属性）。我打赌使用常规的for循环可以解决这个问题。

使用NHibernate EventListener维护非规范化数据

1 个答案: