在以下模型中，地址不应该是值对象吗? [英] Shouldn't in the following model an Address be a Value Object?

问题描述

来自值对象如何存储在数据库中?

:

假定公司和个人都具有相同的邮件地址. 这些语句中的哪一个被认为是有效的?

Assume that a Company and Person both have the same mail Address. Which of these statements do consider valid?

1.如果我修改Company.Address，我希望Person.Address自动获得这些更改"

   1."If I modify Company.Address, I want Person.Address to automatically get those changes"

2.如果我修改Company.Address，则不得影响Person.Address"

   2."If I modify Company.Address, it must not affect Person.Address"

如果1为true，则地址应为实体

If 1 is true, Address should be an Entity

如果2为true，则Address应该是一个值对象.

If 2 is true, Address should be a Value Object.

在上述模型中，邮件Address不应是 Value对象，因为即使Company和Person具有相同的邮件，该邮件也没有概念性身份?

Shouldn't in the above model the mail Address be a Value Object, since even if Company and Person have same mail, this mail still doesn't have a conceptual identity?

换句话说，如果最初Company和Person共享 [e-mail] ，但随后又收到新邮件 [e-mail] ，那么我们可以说邮件地址 [e-mail] 本身没有更改，而是Company和Person替换为 [e-mail] 吗?

In other words, if initially Company and Person share [e-mail], but then get new mail [e-mail], then we can argue that mail address [e-mail] itself didn't changed, instead Company and Person replaced it by [e-mail] ?

据我所知，仅仅共享Address的事实不足以赋予其个性(即身份)吗?！

Thus to my understanding a mere fact that Address is shared shouldn't be enough to give it personality (ie identity)?!

谢谢

推荐答案

是的，您的理解是正确的. 地址几乎应该始终是一个值对象，因为在大多数域中，地址确实只是一个值.

Yes, your understanding is correct. Address should almost always be a value object, since in most domains, the address is indeed just a value.

今天 Company 和 Person 具有相同的 Address 的事实并不意味着如果一个改变，另一个也应该改变.如果存在这样的关系，则应通过显式约束对其进行建模，而不是通过使 Address 为实体.

The fact that a Company and a Person have the same Address today does not mean that if one changes, the other should change too. If such a relationship exists, it should be modeled through an explicit constraint rather than by making Address an entity.

埃里克·埃文斯(Eric Evans)在其，甚至提供了一个具体示例，其中 Address 可能是一个实体-邮政服务，其域围绕地址而行，而单个地址的身份很重要.

Eric Evans talks about this in his excellent book on Domain-Driven Design and even provides a specific example where Address might be an entity -- the postal service, whose domain revolves around addresses, and where the identity of individual addresses is important.

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