如何通过 activerecord 以两种不同的方式关联两个模型？

Question

I'm making a basic forum like app using ruby on rails. I have users that can create groups. Each user has_many groups and each group belongs_to a user. The problem is that I also want a user to be able to subscribe to many groups and for groups to have many subscribed users. I can't figure out how to achieve this.

Here is the ideal code that I would like to be able to write:

class Group < ApplicationRecord
    #working code
    belongs_to :user
    has_many :subscriptions
    #Non working code
    has_many :subscribed_users, through: :subscriptions
end

class User < ApplicationRecord
    #working code
    has_many :groups
    has_many :subscriptions
    #Non working code
    has_many :subscribed_groups, through: :subscriptions
end

class Subscription < ApplicationRecord
   belongs_to :user
   belongs_to :group
end

Answer 1

Try something this:

class Group < ApplicationRecord
  belongs_to :user
  has_many :subscriptions

  has_many :subscribed_users, through: :subscriptions, source: :user
end

class User < ApplicationRecord
  has_many :groups
  has_many :subscriptions

  has_many :subscribed_groups, through: :subscriptions, source: :group
end

class Subscription < ApplicationRecord
  belongs_to :user
  belongs_to :group
end