我需要有“参考资料”吗？我的问题和答案模型中的列？
如果问题和答案之间存在 has_many 和 belongs_to 关系：
class Question < ActiveRecord::Base
has_many :answers
end
class Answer < ActiveRecord::Base
belongs_to :question
end
我是否还需要修改迁移文件以使用“引用”：
class CreateAnswers < ActiveRecord::Migration
def self.up
create_table :answers do |t|
t.text :body
t.references :question
t.timestamps
end
end
def self.down
drop_table :answers
end
end
class CreateQuestions < ActiveRecord::Migration
def self.up
create_table :questions do |t|
t.text :body
t.references :answer
t.timestamps
end
end
def self.down
drop_table :questions
end
end
If I have a has_many and belongs_to relationship between Questions and Answers:
class Question < ActiveRecord::Base
has_many :answers
end
class Answer < ActiveRecord::Base
belongs_to :question
end
Do I also need to modify the migration files to use "references":
class CreateAnswers < ActiveRecord::Migration
def self.up
create_table :answers do |t|
t.text :body
t.references :question
t.timestamps
end
end
def self.down
drop_table :answers
end
end
class CreateQuestions < ActiveRecord::Migration
def self.up
create_table :questions do |t|
t.text :body
t.references :answer
t.timestamps
end
end
def self.down
drop_table :questions
end
end
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外键仅出现在
属于另一个的模型中。The foreign key only goes in the model that
belongs_tothe other.