设计是否可以更合理一点?——关于ORM中业务实体的讨论
今天看到David Hayden写的Castle ActiveRecord - Active Record Pattern Built on NHibernate - Rapid Application Development文章,其中他的实体类设计如下:
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注意到出现了下面这样的两个属性:
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在这个业务实体中,对于Article对象来说,更直观的应该说它属于哪一个Blog,哪一个Category,而不是指定一个整型的值,这种用ID的设计其实是把把数据库结构带入到了业务实体中。我们知道引入ORM,使得我们可以用面向对象的思维来考虑实体间的关系,如果继续使用ID来解决,引入ORM的作用可能就大打折扣了,因此,是否把实体类修改为如下这样更合理一些呢?
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即用这里的两个属性来代替整型的ID:
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估计也有很多朋友会这样去用,下午跟一个朋友讨论时,他说修改前加载Article对象时,加载的仅仅是2个ID,而修改后却要加载Blog,Category对象所有的属性,是否存在性能上的下降?欢迎大家就这个问题说出你的看法。
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