How to get a join table field?

Question

Ruby on Rails

There are two models - Member (participant) and Community (community).
Members can be in multiple communities. The migration and model data looks like this:

#models/member.rb
class Member < ActiveRecord::Base
  has_and_belongs_to_many :communities
end

#models/community.rb
class Community < ActiveRecord::Base
  has_and_belongs_to_many :members
end

#миграция
create_table :communities_members, id: false do |t|
      t.belongs_to :member, index: true
      t.belongs_to :community, index: true
      
      t.timestamps null: false #это важная строчка
end

The links work, I can easily get the members of the group by querying @community.members, etc., but I also need to see the time the link was created (when the person joined the group). To do this, I added the line t.timestamps - in theory, it should automatically add the created_at and updated_at columns.
But I don't understand how to get this value using the active record interface. Can you tell me?
Thanks in advance for your replies.

Answer 1

Just for such purposes, it is recommended to use has_many through instead of has_and_belongs_to_many:

Answer 2

@community.communities_members
Or with the help .joins
Or register scopein one of the existing models.
In fact, there are many ways to implement your idea.