C# - Fluent NHibernate 映射问题

发布于 2024-10-07 19:40:17 字数 686 浏览 2 评论 0原文

有没有办法避免 Fluent NHibernate 中的显式 Id 映射？

我希望它以某种方式自动生成条目 ID，这样我就不必将它作为类的一部分引入。

public class HeyMapping
{
    public String Name { get; set; }
    public DateTime Timestamp { get; set; }
}

public class HeyMapping : ClassMap<HeyMapping>
{
    public HeyMapping()
    {
        Not.LazyLoad();

        // I'm not particularly sure how this line works, but
        // it fails the mapping unit test.
        CompositeId().KeyProperty(x => x.Name);

        Map(x => x.Name).Not.Nullable().Length(64);
        Map(x => x.Timestamp).Not.Nullable();
    }
}

原文

Is there a way to avoid the explicit Id mapping in Fluent NHibernate?

I want it to somehow generate the entry id automatically so that I wouldn't have to introduce it as a part of the class.

public class HeyMapping
{
    public String Name { get; set; }
    public DateTime Timestamp { get; set; }
}

public class HeyMapping : ClassMap<HeyMapping>
{
    public HeyMapping()
    {
        Not.LazyLoad();

        // I'm not particularly sure how this line works, but
        // it fails the mapping unit test.
        CompositeId().KeyProperty(x => x.Name);

        Map(x => x.Name).Not.Nullable().Length(64);
        Map(x => x.Timestamp).Not.Nullable();
    }
}

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坏尐絯 2024-10-14 19:40:17

如果您希望实体中没有 id，您仍然需要映射一个 Id，以便 NHibernate 知道要使用的数据库列。

您可以调用

Id<TColumnDataType>("column_name");

请注意，您将放弃一些 NHibernate 功能（特别是级联更新和调用 SaveOrUpdate() 的能力），并因仅拥有数据库身份而在数据库端产生性能损失（我相信NHibernate将不得不进行额外的查询来进行比较）。

我通常承认这一点，并允许将 Id 作为我的域类中的一个持久性关注点，因此我会这样做：

public class HeyMapping
{
    protected internal int Id { get; set; } // persistence concern

    public virtual String Name { get; set; }
    public virtual DateTime Timestamp { get; set; }
}

我意识到您可能不想这样做；我只是让你知道这是一个权衡。

If you want to have no id in your entity, you still have to map an Id so NHibernate knows the database column to use.

You can call

Id<TColumnDataType>("column_name");

Please note that you will give up some NHibernate functionality (specifically cascading updates and the ability to call SaveOrUpdate()) and incur a performance penalty on the database side for having database-only identity (I believe NHibernate will have to make extra queries for comparison).

I usually concede this point and allow the Id as the one persistence concern in my domain classes, so I would do this:

public class HeyMapping
{
    protected internal int Id { get; set; } // persistence concern

    public virtual String Name { get; set; }
    public virtual DateTime Timestamp { get; set; }
}

I realize you might not want to do this; I'm just letting you know that there is a tradeoff.

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