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OrderStatus应作为值对象 #3

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chenyyyang opened this issue May 29, 2021 · 4 comments
Open

OrderStatus应作为值对象 #3

chenyyyang opened this issue May 29, 2021 · 4 comments

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@chenyyyang
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为何要把OrderStatus加上Id变成实体呢？
@banq
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banq commented May 30, 2021

OrderStatus是值对象，但是表现为数据层的实体，这是JPA技术限制。

@chenyyyang
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谢谢回复，可我还是不懂“但是表现为数据层的实体，这是JPA技术限制”这句的含义。回头我再看看视频哈

@banq
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banq commented May 30, 2021

这句话意思是：数据库是需要主键的，主键是标识，而值对象则是无标识的，那么值对象保存到数据库中是不是一定不能有主键呢，不一定，在DDD中是值对象，但是在数据库中可能就是一个实体数据表，由实体数据表转为的对象称为数据层的实体对象，这个实体对象是DTO或POJO，是贫血对象，与DDD中实体不是一个概念

@chenyyyang
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明白了。感谢

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@banq @chenyyyang