module Notifications
  module Model
    included do
      belongs_to :actor, class_name: Notifications.config.user_class
      belongs_to :user, class_name: Notifications.config.user_class

      belongs_to :target, polymorphic: true
      belongs_to :second_target, polymorphic: true
      belongs_to :third_target, polymorphic: true

      scope :unread, -> { where(read_at: nil) }
    end
  end
end

Error: Command 'notifications:install:migrations' not recognized
Did you mean: `$ rake notifications:install:migrations` ?

ActionView::MissingTemplate in Notifications::Notifications#index
Showing /home/daniel/jexts/app/views/notifications/notifications/_notification.html.erb where line #11 raised:

Missing partial notifications/_comment with {:locale=>[:en], :formats=>[:html], :variants=>[], :handlers=>[:raw, :erb, :html, :builder, :ruby, :coffee, :jbuilder]}. Searched in:
  * "/home/daniel/jexts/app/views"
  * "/home/daniel/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/kaminari-core-1.1.1/app/views"
  * "/home/daniel/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/notifications-0.6.0/app/views"
  * "/home/daniel/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/mailboxer-0.15.1/app/views"
  * "/home/daniel/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/devise-4.4.1/app/views"

StandardError: An error has occurred, this and all later migrations canceled:

Directly inheriting from ActiveRecord::Migration is not supported. Please specify the Rails release the migration was written for:

  class CreateNotifications < ActiveRecord::Migration[4.2]

2019-08-11T07:27:05.920574+00:00 heroku[web.1]: State changed from crashed to starting
2019-08-11T07:27:10.246313+00:00 heroku[web.1]: Starting process with command `bin/rails server -p 23752 -e production`
2019-08-11T07:27:15.427833+00:00 heroku[web.1]: State changed from starting to crashed
2019-08-11T07:27:15.409030+00:00 heroku[web.1]: Process exited with status 1
2019-08-11T07:27:15.316165+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/notifications-0.6.1/app/controllers/notifications/application_controller.rb:5:in `alias_method': undefined method `current_user' for class `Notifications::ApplicationController' (NameError)

private

def create_notifications
    Notification.create do |notification|
        notification.notify_type = 'chapter'
        notification.actor = self.book.user
        notification.user = self.user.followers
        notification.target = self
        notification.second_target = self.book
    end
end

   after_commit :create_notifications, on: :create

    def create_notifications
        Notification.create do |notification|
            notification.notify_type = 'new_review'
            notification.actor = self.user
            notification.user = self.book.user
            notification.target = self
            notification.second_target = self.book
        end
    end

class Comment < ApplicationRecord
  belongs_to :commentable, polymorphic: true
  belongs_to :user
  belongs_to :parent, class_name: 'Comment', optional: true
  has_many :replies, class_name: 'Comment', foreign_key: :parent_id, dependent: :destroy

  validates :content, presence: true, length: { maximum: 255 }

  after_commit :notify_comment_created, on: [:create]
  def notify_comment_created
    return if self.commentable.blank?
    receiver_id = self.commentable&.user_id
    return if receiver_id.blank?
    # notified_user_ids = self.mentioned_user_ids || []
    # return if notified_user_ids.include?(receiver_id)

    Notification.create(
      notify_type: "comment",
      target: self,
      second_target: self.commentable,
      actor_id: self.user_id,
      user_id: receiver_id
    )
  end
end

  has_many :books, dependent: :destroy
  has_many :chapters, dependent: :destroy
  has_many :reviews, dependent: :destroy
  has_many :genres
  has_many :ratings

belongs_to :book
belongs_to :user

after_commit :create_notifications, on: :create

private

def create_notifications
   Notification.create do |notification|
       notification.notify_type = 'book'
       notification.actor = self.user
       notification.user = self.book.user
       notification.target = self
       notification.second_target = self.book
    end
end

<div class=''>
 <%= link_to notification.actor.username, main_app.profile_path(notification.actor.username) %> reviewed
<%= link_to notification.second_target.title, main_app.book_path(notification.second_target) %>
</div>

<div class=''>
   <% unless notification.target.blank? %>
      <div class="review-rating" data-score="<%= notification.target.rating %>"></div>
      <%= notification.target.comment %>
  <% end %>
</div>

belongs_to :user
has_many :chapters, dependent: :destroy

after_commit :create_notifications, on: :create

def create_notifications
    self.user.followers.each do |follower|
      Notification.create(notify_type: 'book', 
                          actor: self.user,
                          user: follower, 
                          target: self, 
                          second_target: self.book)

    end
end

has_many :follower_relationships, foreign_key: :following_id, class_name: 'Follow'
  has_many :followers, through: :follower_relationships, source: :follower

  has_many :following_relationships, foreign_key: :follower_id, class_name: 'Follow'
  has_many :following, through: :following_relationships, source: :following

  def follow(user_id)
    following_relationships.create(following_id: user_id)
  end

  def unfollow(user_id)
    following_relationships.find_by(following_id: user_id).destroy
  end

class RelationshipsController < ApplicationController
  def follow_user
    @user = User.find_by! username: params[:username]
    if current_user.follow @user.id
      respond_to do |format|
        format.html { redirect_to root_path }
        format.js
      end
    end
  end

  def unfollow_user
    @user = User.find_by! username: params[:username]
    if current_user.unfollow @user.id
      respond_to do |format|
        format.html { redirect_to root_path }
        format.js
      end
    end
  end
end

class Follow < ApplicationRecord
	belongs_to :follower, foreign_key: 'follower_id', class_name: 'User'
  	belongs_to :following, foreign_key: 'following_id', class_name: 'User'
end

after_commit :create_notifications, on: :follow

  private

  def create_notifications
    self.user.following.each do |follower|
      Notification.create(notify_type: 'new_follower', actor: self, user: user)
 
    end
  end

  after_commit :create_notifications, on: :follow

  private

# Auto generate with notifications gem.
class Notification < ActiveRecord::Base
  include Notifications::Model

  def self.notify_follow(user_id, follower_id)
    opts = {
      notify_type: "follow",
      user_id: user_id,
      actor_id: follower_id
    }
    return if Notification.where(opts).count > 0
    Notification.create opts
  end
end