要设置属性null的NHibernate EventListener

public class NullPropertyEventListener : IPreUpdateEventListener, IPreInsertEventListener
{
    public bool OnPreUpdate(PreUpdateEvent @event)
    {
        // 获取实体对象
        var entity = @event.Entity;

        // 检查需要设置为null的属性，并将其设置为null
        if (entity is YourEntityClassName yourEntity)
        {
            yourEntity.YourProperty = null;
        }

        return false;
    }

    public bool OnPreInsert(PreInsertEvent @event)
    {
        // 获取实体对象
        var entity = @event.Entity;

        // 检查需要设置为null的属性，并将其设置为null
        if (entity is YourEntityClassName yourEntity)
        {
            yourEntity.YourProperty = null;
        }

        return false;
    }
}

<hibernate-configuration>
  <session-factory>
    <!-- 其他配置项 -->
    
    <!-- 注册自定义事件监听器 -->
    <event type="pre-insert">
      <listener class="YourNamespace.NullPropertyEventListener, YourAssemblyName" />
    </event>
    <event type="pre-update">
      <listener class="YourNamespace.NullPropertyEventListener, YourAssemblyName" />
    </event>
  </session-factory>
</hibernate-configuration>