RoR - 通过关联创建的外键并迁移或“手动”创建（或脚手架）？
刚刚开始学习 Ruby on Rails。我正在使用 RoR 3。我已阅读以下内容： http://guides.rubyonrails.org/association_basics.html
但我想确保我完全理解。
创建新模型时（我现在通过脚手架进行），我应该在此时指定foreign_key字段，还是关联可以完全处理该字段？我相信关联仅在应用程序级别，而不是在数据库级别，对吗？
所以我认为我必须这样做：
rails generate scaffold post body:text title:string user_id:integer
所以总而言之，在创建博客应用程序时，我必须在帖子模型中指定 user_id 字段，还是用户模型的 has_many :posts 负责实际将其添加到我迁移时的数据库（我的是mysql）？
如果答案是我应该在首先创建模型时（通过脚手架或手动）执行这些操作，那么当我稍后决定要添加外键时会发生什么，我是否必须将其添加为 <在新迁移中执行 code>execute 语句？
Just starting to learn Ruby on Rails. I'm using RoR 3. I have read this: http://guides.rubyonrails.org/association_basics.html
But I want to make sure I understand completely.
When creating a new model (I'm doing via scaffold for now), should I specify foreign_key fields at that point, or does the association handle that completely? I believe that association is only at app level, not at the db level, correct?
So I think I must do:
rails generate scaffold post body:text title:string user_id:integer
So in summary, when creating a blog application, must I specify the user_id field in the post model, or does the user model's has_many :posts take care of actually adding that to the db (mine is mysql) when I migrate?
And if the answer is that I should do them when I create the model in the first place (via scaffold or by hand), what happens when I decide later on that I want to add a foreign key, must I add that as an execute statement in a new migration?
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你是对的。您需要在创建脚手架/模型/迁移时指定外键，如您所说，以使数据库正确，并且 has_many 会为您处理模型。
因此，对于支架（或模型）的初始生成，只需执行：
如您所述，并为模型本身添加
has_many。对于稍后的添加，您将构建一个新的迁移，例如（假设您想使用生成，但您可以编写自己的迁移）：
这样，您可以运行
rake db:migrate，然后使用has_many或您需要的任何关联更新您的模型。You're correct. You need to specify the foreign key when you create your scaffold/model/migration as you stated to get the DB to be correct, and the has_many takes cares of the model for you.
So for initial generation of a scaffold (or model), just do:
as you stated, and add the
has_manyfor the model itself.For additions later on, you would make up a new migration, something like (assuming you want to use generation, but you could write your own migration):
With that, you can run a
rake db:migrate, and then update your model with ahas_manyor whatever association you need.