了解Rails关联(Understanding Rails associations)

 我正在学习Rails，我正在尝试将Ruby与创建关联时正在发生的事情联系起来。 例如： 
 
class Post < ActiveRecord::Base
  belongs_to :user
end

class User < ActiveRecord::Base
  has_many :posts
end
 
 我在网上阅读了一篇解释，其中将belongs_to和has_many的使用与Ruby中的attr_accessor联系起来。 这有点令人困惑......怎么会这样？ 据我所知，这设置了Post和User之间的1：M关联，特别是Post有一个包含用户ID的外键。 在rails控制台中，我可以执行以下操作： 
 
user = User.first
user.posts 
user2 = User.create(username: 'some guy').save
post2 = Post.new(title: 'stuff', body: 'some more stuff')
user2.posts << post2 
 
 那些类似'getter'和'setter'的方法，其中每个类的对象对应于数据库中的特定行，我可以使用这些方法，因为它们的关联/关系？ 

I'm learning Rails and I'm trying to connect the dots between Ruby and what's going on when creating associations. For example:
 
class Post < ActiveRecord::Base
  belongs_to :user
end

class User < ActiveRecord::Base
  has_many :posts
end
 
I've read an explanation online that relates the use of belongs_to and has_many here to attr_accessor in Ruby. This is a tad confusing ... how is that so? I understand this sets up the 1:M association between Post and User, specifically Post has a foreign key containing a user id. In the rails console, I can do something like:
 
user = User.first
user.posts 
user2 = User.create(username: 'some guy').save
post2 = Post.new(title: 'stuff', body: 'some more stuff')
user2.posts << post2 
 
So are these kind of like 'getter' and 'setter' methods where an object of each class corresponds to a specific row in the database and I can use these methods because of their association/relationship?

原文：https://stackoverflow.com/questions/27498071