迁移has_one和has_many

Question

class Post < ActiveRecord::Base
  has_one :owner, class_name: "User", foreign_key: "owner_id" #creator post
  has_many :users #followers post
end

class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
     :recoverable, :rememberable, :trackable, :validatable

 has_many :posts 
 end

为了在用户表和Post表之间执行这些不同的关系，我需要执行哪些命令行来迁移？谢谢

Answer 1

belong_to:owner，应该是Post，因为posts表有外键。而且，它的#users和User#posts的名字有点太模糊了。

这是你们的模特：

class Post < ActiveRecord::Base
  belongs_to :owner, class_name: 'User', inverse_of: :owned_posts # foreign_key: :owner_id will be inferred
  has_many :subscriptions
  has_many :followers, through: :subscriptions, source: :user, class_name: 'User', inverse_of: :followed_posts
end

class Subscription < ActiveRecord::Base
  belongs_to :post
  belongs_to :user
end

class User < ActiveRecord::Base
  has_many :owned_posts, class_name: 'Post', inverse_of: :owner
  has_many :subscriptions
  has_many :followed_posts, through: :subscriptions, source: :post, class_name: 'Post', inverse_of: :followers
end

以下是支持他们的迁徙：

class CreateUsers < ActiveRecord::Migration
  def change
    create_table :users do |t|
      # ...
    end
  end
end

class CreatePosts < ActiveRecord::Migration
  def change
    create_table :posts do |t|
      t.integer :owner_id
      # ...
    end
  end
end

class CreateSubscriptions < ActiveRecord::Migration
  def change
    create_table :subscriptions do |t|
      t.integer :post_id
      t.integer :user_id
    end
  end
end

如果不是因为“所有权”关系，那么可以使用has_and_belongs_to_many关系：

1. 将subscriptions迁移重命名为posts_users (必须按字母顺序为复数)，
2. 完全废除它的模式，并且
3. 有Post.has_and_belongs_to_many :users和User.has_and_belongs_to_many :posts。

实际上，从技术上讲，您可以做到这一点，但是使用这样的模糊名称是一种糟糕的做法。