rails-api & Warden

authentication_token_strategy.rb

# lib/strategies/authentication_token_strategy.rb
class AuthenticationTokenStrategy < ::Warden::Strategies::Base
  def valid?
    authentication_token
  end

  def authenticate!
    user = User.find_by_authentication_token(authentication_token)
    user.nil? ? fail!('strategies.authentication_token.failed') : success!(user)
  end

  private
  def authentication_token
    params['authentication_token']
  end
end

create_users.rb

class CreateUsers < ActiveRecord::Migration
  def change
    create_table :users do |t|
      t.string :username
      t.string :authentication_token
      t.string :password_digest

      t.timestamps null: false

      t.index :authentication_token, unique: true
    end
  end
end

routes.rb

# config/routes.rb
Rails.application.routes.draw do
  get 'welcome/index'.
  root 'welcome#index'
end

unauthorized_controller.rb

# app/controllers/unauthorized_controller.rb
class UnauthorizedController < ActionController::Metal
  def self.call(env)
    @respond ||= action(:respond)
    @respond.call(env)
  end

  def respond
    self.response_body = "Unauthorized Action"
    self.status = :unauthorized
  end
end

user.rb

# app/models/user.rb
class User < ActiveRecord::Base
  after_create :generate_authentication_token!

  has_secure_password

  private
  # Generate a session token
  def generate_authentication_token!
    self.authentication_token = Digest::SHA1.hexdigest("#{Time.now}-#{self.id}-#{self.created_at}")
    self.save
  end
end

warden_helper.rb

# app/controllers/concerns/warden_helper.rb
module WardenHelper
  extend ActiveSupport::Concern

  included do
    helper_method :warden, :signed_in?, :current_user

    prepend_before_filter :authenticate!
  end

  def signed_in?
    !current_user.nil?
  end

  def current_user
    warden.user
  end

  def warden
    request.env['warden']
  end

  def authenticate!
    warden.authenticate!
  end
end

welcome_controller.rb

# app/controllers/welcome_controller.rb
class WelcomeController < ApplicationController
  def index
    render text: "Welcome guest, it's #{Time.now}"
  end
end