Ruby on rails 你自己也经历过一些事情吗

所以，我有一个系统，用户可以跟随作者（其他用户）

用户型号：

  class User < ActiveRecord::Base
    has_many :author_following, class_name: 'Following'
    has_many :following, through: :author_following, source: :author
    has_many :followers, foreign_key: 'author_id', through: :author_following, source: :user
  end

  class Following < ActiveRecord::Base
    belongs_to :user
    belongs_to :author, foreign_key: 'author_id', class_name: "User"
  end

  class User < ActiveRecord::Base
    has_many :author_following, class_name: 'Following'
    has_many :following, through: :author_following, source: :author
    has_many :author_followers, foreign_key: 'author_id', class_name: 'Following'
    has_many :followers, through: :author_followers, source: :user
  end

  class Following < ActiveRecord::Base
    belongs_to :user
    belongs_to :author, class_name: "User"
  end

这是正确的

u.followers

生成以下SQL：

    SELECT "users".* FROM "users" INNER JOIN "followings" ON "users"."id" = "followings"."user_id" WHERE "followings"."user_id" = $1  [["user_id", 1]]

这是错误的

---

理想情况下这个SQL应该是

其中的“followers”。“author_id”=$1

当然，在发布问题后，我认为这是您的权利。但是，如果您认为有一种更优雅的方法可以做到这一点，请评论：）

为了解决这个问题，我改变了：

用户型号：

  class User < ActiveRecord::Base
    has_many :author_following, class_name: 'Following'
    has_many :following, through: :author_following, source: :author
    has_many :followers, foreign_key: 'author_id', through: :author_following, source: :user
  end

  class Following < ActiveRecord::Base
    belongs_to :user
    belongs_to :author, foreign_key: 'author_id', class_name: "User"
  end

  class User < ActiveRecord::Base
    has_many :author_following, class_name: 'Following'
    has_many :following, through: :author_following, source: :author
    has_many :author_followers, foreign_key: 'author_id', class_name: 'Following'
    has_many :followers, through: :author_followers, source: :user
  end

  class Following < ActiveRecord::Base
    belongs_to :user
    belongs_to :author, class_name: "User"
  end

class用户

以下型号：

  class User < ActiveRecord::Base
    has_many :author_following, class_name: 'Following'
    has_many :following, through: :author_following, source: :author
    has_many :followers, foreign_key: 'author_id', through: :author_following, source: :user
  end

  class Following < ActiveRecord::Base
    belongs_to :user
    belongs_to :author, foreign_key: 'author_id', class_name: "User"
  end

  class User < ActiveRecord::Base
    has_many :author_following, class_name: 'Following'
    has_many :following, through: :author_following, source: :author
    has_many :author_followers, foreign_key: 'author_id', class_name: 'Following'
    has_many :followers, through: :author_followers, source: :user
  end

  class Following < ActiveRecord::Base
    belongs_to :user
    belongs_to :author, class_name: "User"
  end

类后面的

另一种方法是使用

has\u和\u属于\u many

。不需要第二个模型

class User < ActiveRecord::Base
  has_and_belongs_to_many :followers, class_name: 'User', foreign_key: 'follower_id'
  has_and_belongs_to_many :followees, class_name: 'User', foreign_key: 'followee_id'
end

# Migration
create_table :followees_followers do |t|
  t.belongs_to :followee
  t.belongs_to :follower
end

class用户

---

这很简单，但是验证部分（比如验证某人是作者）需要在用户模型中完成

@上面Billy Chan的答案很接近，但是您还需要指定关系的另一面以及“关联外键”，并在我们这边将followee\u id与followee\u id切换。此外，联接表实际上是用户

class User < ActiveRecord::Base
  has_and_belongs_to_many :followers, class_name: 'User', 
     foreign_key: 'followee_id', association_foreign_key: 'follower_id'
  has_and_belongs_to_many :followees, class_name: 'User', 
     foreign_key: 'follower_id', association_foreign_key: 'followee_id'
end

  # Migration
    create_table :users_users do |t|
       t.belongs_to :followee
       t.belongs_to :follower
    end

class用户

---

现在User.followers和User.followeres按预期工作

非常简单。我喜欢它：D@MichaelLynch，我的荣幸。从理论上讲，它应该可以工作，虽然没有经过验证：）这不会工作，rails会在另一种关系上寻找用户id。6年后，你救了我一天，想不出更好的方法用rails 6实现这一点