has_many through same table Rails - ruby-on-rails

Question

I want to create a Rails app that allows "users" to follow other users. I am semi-new to more complex relationships and am attempting to set up has_many through for the first time. I want friends to be able to follow other users.
Here is my join table:
class Following < ApplicationRecord
belongs_to :user
belongs_to :follower, class_name: "User"
end
Here is my users table:
class User < ApplicationRecord
has_many :followings
has_many :followers, through: :followings
end
Here is my schema:
create_table "followings", force: :cascade do |t|
t.integer "user_id"
t.integer "follower_id"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
create_table "users", force: :cascade do |t|
t.string "name"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
I don't know how to set up a form to actually create the relationship. In a users view, I have this, but it doesn't work.
<%= form_for #following do |f| %>
<%= f.hidden_field :follower_id, :value => #user %>
<%= f.select :user_id, #users.collect { |u| [u.name, u.id] } %>
<%= f.submit %>
<% end %>
As I said, I am very new to this type of relationship. I need help. I don't know how to link records through a form.
I am following this tutorial: https://teamtreehouse.com/library/what-is-a-hasmany-through-association-in-ruby-on-rails

Answer 1

I am assuming you have a current_user method that returns the logged in user - like what Devise provides. If not you need to setup authentication first.
Create a nested route:
# config/routes.rb
resources :users, only: [] do
resources :followings, only: [:create, :destroy], shallow: true
end
Add a validation to Following to avoid duplicates:
class Following < ApplicationRecord
belongs_to :user
belongs_to :follower, class_name: "User"
validates_uniqueness_of :user_id, scope: 'follower_id'
end
Add a utility method to User to see if he is following another user:
class User < ApplicationRecord
has_many :followings
has_many :followers, through: :followings
def following?(user)
followings.exist?(user: user)
end
def find_following(user)
followings.find_by(user: user)
end
end
We can then add Follow and Unfollow buttons (they are actually forms) to the /users/show.html.erb view.
<% if current_user.following?(#user) %>
<%= button_to "Unfollow", current_user.find_following(#user), method: :delete %>
<% else %>
<%= button_to "Follow", [#user, #user.followings.new] %>
<% end %>
Note that we don't need any form params since we are using a nested route (POST /users/:user_id/followings) to pass the user id (who gets followed) and we are getting the current user from the session.
We can then setup our controller:
class FollowingsController < ApplicationController
# POST /users/:user_id/followings
def create
#user = User.find(params[:user_id])
#following = Following.new(user: #user, follower: current_user)
if #following.save
redirect_to #user, success: "You are now following #{ #user.name }"
else
redirect_to #user, error: "Could not create following"
end
end
# DELETE /followings/:id
def destroy
#following = Following.find(params[:id])
#following.destroy
redirect_to #following.user, success: "You are no longer following #{ #user.name }"
end
end