NHibernate的IPreUpdateEventListener，IPreInsertEventListener不保存到数据库

问题描述

我想实现我的实体简单的审计。审计实体实施 ITimestampable 接口，它定义了 DateAdded 和 DateModified 属性。

I'm trying to implement simple auditing on my entities. Auditable entities implement the ITimestampable interface which defines DateAdded and DateModified properties.

我创建并注册一个事件侦听器来填充这些值。这里是完整的代码

I created and registered a event listener to populate these values. Here is the complete code.

internal class TimeStampEventListener : IPreUpdateEventListener, IPreInsertEventListener
    {
        public bool OnPreUpdate(PreUpdateEvent e)
        {
            if (e.Entity is ITimestampable)
            {
                (e.Entity as ITimestampable).DateModified = DateTime.Now;
            }

            return false;
        }

        public bool OnPreInsert(PreInsertEvent e)
        {
            if (e.Entity is ITimestampable)
            {
                (e.Entity as ITimestampable).DateAdded = DateTime.Now;
            }

            return false;
        }

        public void Register(Configuration configuration)
        {
            configuration.SetListener(ListenerType.PreInsert, this);
            configuration.SetListener(ListenerType.PreUpdate, this);
        }
    }

现在，当我提出一个会话红晕，监听器被调用，审计属性都设置正确，但大多数时候他们不会保存到数据库。通过大部分时间我的意思是很少的价值真正得到坚持。我不知道，但它看起来像上的应用程序启动后的第一个插入/更新，这更加怪异。

Now, when I make a session flush, the listener gets called, audit properties are correctly set, but most of the time they are not saved to the DB. By "most of the time" I mean that very rarely the values actually get persisted. I'm not sure, but it looks like on the first insert/update after the app is started, which is even more weird.

当然，首先我做一个更改为实体的变化仍然存在，但审计属性不是。

Of course, first I make a change to the entity, the change is persisted, but the audit property is not.

当我看到在事件探查器生成的SQL我看到NULL是寄于查询，而不是当前的时间，所以我猜它不是一个DB的问题。顺便说一句。我使用MySQL和 DateAdded 和 DateModified 列是日期键入

When I look at the generated SQL in the profiler I see that NULL is send in the query instead of the current time, so I'm guessing it is not a DB issues. Btw. I'm using MySQL and DateAdded and DateModified column are DATE type.

在NHibernate的网站，这些属性映射仅作为<性> 。也许我错过了一些特殊的映射，这样的情况下...？

On the NHibernate site these properties are mapped only as <property>. Maybe I'm missing some "special" mapping for cases like these... ?

我完全停留在此。任何形式的帮助表示赞赏。

I'm completely stuck on this. Any kind of help is appreciated.

推荐答案

答案将被隐藏/这表明从Ayende的文章引用

The answer would be hidden/revealed in this cites from Ayende's article

• NHibernate IPreUpdateEventListener & IPreInsertEventListener

...这里说到的精妙，但是。我们不能只更新实体状态。这其中的原因很简单，是从实体状态实体和地方，任何更改，我们对实体状态将不会反映在实体本身中提取的实体状态。可能导致数据库行和走出去同步，并引起一大堆真的讨厌的问题，你不知道从哪里开始调试实体实例。

您必须更新两个在这两个事件侦听器实体和实体状态（这个不一定在其他听众的情况下，顺便说一句）。下面是使用这些事件侦听器的一个简单的例子：

You have to update both the entity and the entity state in these two event listeners (this is not necessarily the case in other listeners, by the way). Here is a simple example of using these event listeners:

这是显示的代码如何，从同一篇文章：

This is the code showing how to, from the same article:

public class AuditEventListener : IPreUpdateEventListener, IPreInsertEventListener
{
    public bool OnPreUpdate(PreUpdateEvent @event)
    {
        var audit = @event.Entity as IHaveAuditInformation;
        if (audit == null)
            return false;

        var time = DateTime.Now;
        var name = WindowsIdentity.GetCurrent().Name;

        Set(@event.Persister, @event.State, "UpdatedAt", time);
        Set(@event.Persister, @event.State, "UpdatedBy", name);

        audit.UpdatedAt = time;
        audit.UpdatedBy = name;

        return false;
    }

    public bool OnPreInsert(PreInsertEvent @event)
    {
        var audit = @event.Entity as IHaveAuditInformation;
        if (audit == null)
            return false;


        var time = DateTime.Now;
        var name = WindowsIdentity.GetCurrent().Name;

        Set(@event.Persister, @event.State, "CreatedAt", time);
        Set(@event.Persister, @event.State, "UpdatedAt", time);
        Set(@event.Persister, @event.State, "CreatedBy", name);
        Set(@event.Persister, @event.State, "UpdatedBy", name);

        audit.CreatedAt = time;
        audit.CreatedBy = name;
        audit.UpdatedAt = time;
        audit.UpdatedBy = name;

        return false;
    }

和这里是神奇的设置（）

private void Set(IEntityPersister persister, object[] state
       , string propertyName, object value)
{
    var index = Array.IndexOf(persister.PropertyNames, propertyName);
    if (index == -1)
        return;
    state[index] = value;
}

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