Follow user- logic

Question

I'm working on Ruby on rails 2.3.8, and I'd like to build a functionality to follow users.

For this purpose, I've created 2 tables: users and followings, with their respective models:

class User < ActiveRecord::Base
  has_and_belongs_to_many :followings, :foreign_key => "follower_id"
end

class Following < ActiveRecord::Base
  has_and_belongs_to_many :users, :foreign_key => "follower_id", :class_name => "User"
end

Now, when I try to execute current_user.followings.all (with a valid current_user, of course), it throws me the following exception:

'followings_users' doesn't exist: SELECT 'followings'.* FROM `followings`  INNER JOIN 'followings_users' ON 'followings'.id = 'followings_users'.following_id WHERE ('followings_users'.follower_id = 1 )

I can't make this work. I don't know why it asks me for a "followings_users" table. What if I want to call it just "followings"?

What am I doing wrong here?

Answer 1

When using habtm, Rails will try to get the associations from a join table. It tries to guess the name of the table by joining the two names (followings_users), or you can specify the name of the table as an option. But you have to explicitely create this table in your migrations.

See documentation here

Answer 2

You can also do this using the newer syntax has_many :through:

class User < ActiveRecord::Base
  has_many :user_followings
  has_many :followings, :through => :user_followings
end

class UserFollowing < ActiveRecord::Base
  belongs_to :users
  belongs_to :followings
end

class Following < ActiveRecord::Base
end

This requires a join table called :user_followings with columns user_id and following_id.

The new syntax is generally preferred over HABTM because it allows you to define methods on the join model, which can be useful, although HABTM still works fine as well.

Answer 3

Well, I've found a great solution here: http://railstutorial.org/chapters/following-users?version=2.3#top

Thanks for your answers though.