Ruby-on-rails Rails 模型 has_many ，belongs_to 关系
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Rails model has_many , belongs_to relations
提问by lesce
I have 2 models
我有2个模型
class User < ActiveRecord::Base
has_many :products
end
class Product < ActiveRecord::Base
belongs_to :user
end
Do I need to add a column user_id to the Product table or does rails add it by default ?
我需要在 Product 表中添加列 user_id 还是 rails 默认添加它？
回答by Andre Bernardes
You do need to manually add the user_idcolumn to the Productmodel. If you haven't created your model yet, add the reference in the column list to the model generator. For example:
您确实需要手动将user_id列添加到Product模型中。如果您尚未创建模型，请将列列表中的引用添加到模型生成器。例如：
rails generate model Product name:string price:decimal user:references
rails generate model Product name:string price:decimal user:references
Or, if your Productmodel already exists what you have to do is:
或者，如果您的Product模型已经存在，您必须做的是：
rails g migration addUserIdToProducts user_id:integer
rails g migration addUserIdToProducts user_id:integer
That will generate a migration that properly add the user_idcolumn to the productstable. With the column properly named (user_id), Rails will know that's your foreign key.
这将生成一个迁移，将user_id列正确添加到products表中。正确命名列 (user_id) 后，Rails 将知道这是您的外键。
