我是NHibernate的新手。所以,我想在NHibernate框架中使用Isession更新数据库中的单个元素。
我不知道nhibernate中Update(Object obj,Object id)和Update(string entity,Object obj)之间有什么不同?
有谁知道吗?或者将元素更新为db的另一种方法?
答案 0 :(得分:0)
正如ISession.cs:
中所述/// <summary>
/// Update the persistent state associated with the given identifier.
/// </summary>
/// <remarks>
/// An exception is thrown if there is a persistent instance with the same identifier
/// in the current session.
/// </remarks>
/// <param name="obj">A transient instance containing updated state</param>
/// <param name="id">Identifier of persistent instance</param>
void Update(object obj, object id);
/// <summary>
/// Update the persistent instance with the identifier of the given detached
/// instance.
/// </summary>
/// <param name="entityName">The Entity name.</param>
/// <param name="obj">a detached instance containing updated state </param>
/// <remarks>
/// If there is a persistent instance with the same identifier,
/// an exception is thrown. This operation cascades to associated instances
/// if the association is mapped with <tt>cascade="save-update"</tt>.
/// </remarks>
void Update(string entityName, object obj);
也许Update(obj):
/// <summary>
/// Update the persistent instance with the identifier of the given transient instance.
/// </summary>
/// <remarks>
/// If there is a persistent instance with the same identifier, an exception is thrown. If
/// the given transient instance has a <see langword="null" /> identifier, an exception will be thrown.
/// </remarks>
/// <param name="obj">A transient instance containing updated state</param>
void Update(object obj);
第一种情况是关于使用提供的ID更新具有obj
状态的行。它的ID不是那么重要
第二个,期望,该会话未加载该对象。 entityName
有助于找出正确的持久性(与实体相关的hbm.xml映射)
最后,简单的Update(obj)
几乎与第一个一样,但是ID是从传递的obj
一般情况下,如果我们在会话中加载任何实体,则不必调用Update()
- 只需刷新()。更新有助于明确说:可能实例正在存在。最优选的方法是致电SaveOrUdpate(obj)
,请参阅