Follow function (Ajax) implementation

I will put it together for myself.

Implementation

Modeling

$ rails g model Relationship follower_id:integer followed_id:integer
$ rails db:migrate

Migration file

20200723070930_create_relationships.rb

class CreateRelationships < ActiveRecord::Migration[5.2]
  def change
    create_table :relationships do |t|
      t.integer :follower_id, null: false
      t.integer :followed_id, null: false

      t.timestamps
    end
  end
end

relationship.rb

class Relationship < ApplicationRecord

  #Users to follow
  belongs_to :follower, class_name: 'User'
  #Users to be followed
  belongs_to :followed, class_name: 'User'

  validates :follower_id, presence: true
  validates :following_id, presence: true

end

** class_name:'User' **: means "both follower and followed are in User"

app/models/user.rb

class User < ApplicationRecord

  #Get follow
  has_many :follower, class_name: 'Relationship', foreign_key: 'follower_id', dependent: :destroy

  #Get followers
  has_many :followed, class_name: 'Relationship', foreign_key: 'followed_id', dependent: :destroy

  #The person you are following
  has_many :following_user, through: :follower, source: :followed

  #People who follow me (followers)
  has_many :follower_user, through: :followed, source: :follower


  #Follow users
  def follow(user_id)
    follower.create(followed_id: user_id)
  end

  #Unfollow users
  def unfollow(user_id)
    follower.find_by(followed_id: user_id).destroy
  end

  #Follow confirmation
  def following?(user)
    following_user.include?(user)
  end

end

Controller creation

$ rails g controller relationships

config/routes.rb

Rails.application.routes.draw do

  post 'follow/:id', to: 'relationships#follow', as: 'follow'
  post 'unfollow/:id', to: 'relationships#unfollow', as: 'unfollow'
  get 'users/following/:user_id', to: 'users#following', as: 'users_following'
  get 'users/follower/:user_id', to: 'users#follower', as: 'users_follower'

end

users_controller.rb

class UsersController < ApplicationController

  # @List of users that user is following
  def following
    @user = User.find(params[:user_id])
    @followings = @user.following_user
  end

  # @List of users following user
  def follower
    @user = User.find(params[:user_id])
    @followers = @user.follower_user
  end

end

relationship_controller.rb

class RelationshipsController < ApplicationController

    #To follow
    def follow
      @user = User.find(params[:id])
      current_user.follow(params[:id])
      render :create
    end
  
    #Unfollow
    def unfollow
      @user = User.find(params[:id])
      current_user.unfollow(params[:id])
      render :destroy
    end
    
end

By calling create.js.erb and destroy.js.erb with render, You will be able to follow / unfollow without page transitions.

ruby:users/show.html.slim

# create.js.erb and destroy.js.Description is required to rewrite with erb
div id="follow_form"

  #Partially skip the follow button part
  = render 'relationships/follow', user: @user 

Manually create the _follow.html.slim file under the relationships directory Paste the description of the follow button part that was skipped in the partial.

ruby:relationships/_follow.html.slim

- unless user == current_user
  - if current_user.following?(user)
  
    #remote to call js file:Add true
    = link_to unfollow_path(user), method: :post, remote: true, class: 'btn btn-outline-info m-0 btn-sm' do
      i.fas.fa-user following
  - else
  
    #remote to call js file:Add true
    = link_to follow_path(user), method: :post, remote: true, class: 'btn btn-outline-success m-0 btn-sm' do
      i.far.fa-user follow

Manually create the create.js.erb file under the relationships directory

ruby:relationships/create.js.erb

#　id="follow_form"Part_follow.html.Rewrite slim content without page transition
$('#follow_form').html("<%= j(render 'relationships/follow',{ user: @user }) %>");

Manually create the destroy.js.erb file under the relationships directory

ruby:relationships/destroy.js.erb

#　id="follow_form"Part_follow.html.Rewrite slim content without page transition
$('#follow_form').html("<%= j(render 'relationships/follow',{ user: @user }) %>");

Complete!