为什么Rails隐藏id列的存在？ [英] Why Rails hides the existence of id column?

问题描述

我不太了解是否需要在Rails中隐藏 id 列的存在。
它既没有反映在 migration 文件中，也没有反映在 schema.rb 文件中。
对于新手来说，由于默认情况下已创建名为 id 的列作为主键。
除非他们去检查数据库中表的实际架构（ rails dbconsole ）。

I don't quite understand the need to hide the existence of id column in Rails. It is neither reflected in migration file nor the schema.rb file. There is no way for a newbie to know for the fact that a column named id has been created by default as a primary key. Unless they go and check the actual schema of the table in database (rails dbconsole).

我可以看到默认情况下，迁移文件以及 schema.rb 中包含的 timestamps 宏是两个字段， code> created_at 和 updated_at 。在这里，开发人员至少会有所了解。 Rails也可以对 id 列执行相同的操作。但事实并非如此。

I can see the timestamps macro included by default in the migration file as well as in schema.rb as two fields created_at and updated_at. Here, a developer at least gets a clue. Rails could have done the same for id column too. But it doesn't.

为什么围绕 id 列保密？它是否是著名的约定上的配置的一部分？还是在所有MVC框架中都是规范？

Why the secrecy around id column? Is it a part of the famous convention over configuration? Or is it a norm across all MVC frameworks?

推荐答案

在数据库设计中，通常接受首选数字ID，因为

In database design it is generally accepted that numeric id's are preferred, because

• 它们更易于索引，因此在创建链接（外键）时更易于关注或检查。


• 在编辑/更新记录时，您具有唯一（且有效的）标识符

因此，建议始终为所有表提供唯一的数字键。

So therefore it is advised to give all tables a unique numeric key, always.

现在，此数字键对您的应用程序毫无意义，它是数据库层的实现细节。还要确保每个表都有一个ID，除非您明确要求不要这样做。

Now this numeric key has no meaning whatsoever to your application, it is a "implementation detail" of your database layer. Also to make sure every table has an id, unless you explicitly ask not to.

我认为这确实属于常规配置之上的范畴：为什么要明确指定

I think this would indeed fall under the "convention over configuration" nomer: why explicitly specify an id for each table if you each table should have one.

时间戳是不同的：对于某些表来说这很有趣，但是对于相同的表则根本不重要。这也取决于您的应用程序。

The timestamps is different: this is interesting for some tables, but for same tables it is not important at all. It also depends on your application.

请注意，这与MVC根本无关。 MVC中的M是数据的容器，但是在MVC中，如何填充模型实际上并不重要。换句话说：ORM部分不是MVC的一部分。您会看到，在大多数MVC实现中，没有ORM，或者绝对没有与Rails紧密集成。

Note that this is not at all related to MVC. The M in MVC is a container for data, but in MVC it is actually not really important how the Model gets filled. In other words: the ORM part is not part of MVC. You will see that in most MVC implementations there is no ORM, or definitely not as tightly integrated as with Rails.

简而言之：恕我直言，从迁移中省略 id并不是秘密，它只是使生活更轻松，为您节省了更多打字时间，并且可以确保您遵循良好的约定，除非您明确不想要这样做。

So in short: imho ommitting the 'id' from the migration is not a secret, it is just to make life easier, saves you some more typing, and it makes sure you follow a good convention unless you explicitly do not want to.

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