Rails app

application_controller.rb

class ApplicationController < ActionController::Base
  before_action :authenticate!
end

auth_helper.rb

module AuthHelper

  def authenticate!
    error!('Unauthorized', 401) unless current_user
  end

  def current_user
    user = Rails.cache.fetch(cookies[:guid]) { User.find_by_guid(cookies[:guid]) } if cookies[:guid]
    if user.nil?
      Rails.cache.delete(cookies[:guid]) if cookies[:guid]
      return nil
    end
    Rails.cache.write("#{user.guid}_online", true, expires_in: 20.minutes)
    user.auth_updates
    User.current_user = user
    @current_user = user
  end

end

user.rb

class User < ApplicationRecord
  has_many :received_likes, class_name: 'Like', foreign_key: :to_user_id
  has_many :sended_likes, class_name: 'Like', foreign_key: :from_user_id

  has_many :activities
  has_many :photos, :foreign_key => 'guid', :primary_key => 'guid'

  belongs_to :city
  belongs_to :country

  cattr_accessor :current_user

  validates_presence_of :guid, :name
  validates_uniqueness_of :guid

  def online
    Rails.cache.read("#{guid}_online") || false
  end

  def all_photos
    Photo.where(guid: guid).order(:order_num).pluck(:name)
  end

  def json_response
    {id: id, name: name, city_id: city_id, country_id: country_id, gender: gender, photos: all_photos,
     online: online, liked: liked_from_current_user?, like_current_user: like_to_current_user?}
  end

  def liked_from_current_user?
    received_likes.where(from: User.current_user).exists?
  end

  def like_to_current_user?
    sended_likes.where(to: User.current_user).exists?
  end

  def unread_count
    unread_activities_count + unread_messages_count
  end

  def unread_activities_count
    activities.unread.count
  end

  def unread_messages_count
    Message.unread.where(to_user_id: id).group(:chat_id).count.size
  end
end

users_controller.rb

class UsersController < ApplicationController
  def me
    render json: current_user.json_response
  end
end