Devise (Authentication)

• Useful for authentication needs (allowing for signing in, sending password recovery ...)
• Rails engine (rails app that belongs within another rails app)
  • contains its own set of views and controllers (but no models)

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Installation and Use

• Add to gemfile: gem 'devise
• Run bundle install
• Run the installer: rails generate devise:install
  • This creates a massive file in config/initializers/devise.rb
• Generate the User model with: rails g devise User
• Run rake routes
• Run rake db:migrate
• rails g controller Home
  • create home#index with views
• Head into config/routes.rb, add root 'home#index'
• Test out the authorization, place before_action :authenticate_user! above index action
  • Upon refresh, should take you to the login page
  • Preferrable to add this filter in ApplicationController to keep code dry instead of adding to every controller

Implementing a Sign Out Option

<%= link_to("Sign Out", destroy_user_session_path, :method => 'delete') %>

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Adding the user model migration Rails (5.x.x)

• rails g migration AddUserRefToTableName user:references (where TableName refers to the table that belongs_to a user)
• Add the following:

def change
  add_reference :posts, :user, foreign_key: true, index: true
  # add_foreign_key :posts, :users
end

• May not need the add_foreign_key part, error when migrating
• The example uses the users table
  • The add_foreign_key is used to ensure referential integrity
  • It adds a foreign_key to the user_id column of the posts table
  • The key then references the id column of the users table

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Helpers:

• before_action :authenticate_user!: authenticates the user to be able to access certain pages
  • If your model is not User, say Person, just replace _user with _person , generically _modelname
• user_signed_in: verifies if a user is signed in
• current_user: to find the currently signed in user

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Overriding Default Path for signing in and signing out

• Devise looks for a root_path to redirect to after signing in and signing out.
  • If using a User model, Devise will look for the path: user_root_path if it exists, otherwise, the default root_path will be used
• You can override this redirection by using: after_sign_in_path and after_sign_out_path

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Devise Password

• Devise's users table contains a field for encrypted_password
• Inside of database_authenticatable, password is also used as an attr_reader and setter method:

# Generates a hashed password based on the given value.
# For legacy reasons, we use `encrypted_password` to store
# the hashed password.
def password=(new_password)
  @password = new_password
  self.encrypted_password = password_digest(@password) if @password.present?
end

• You can refer to password in you DB seeding and encrypted_password will also be set!

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Using Omniauth

• Add this line to user.rb:

devise :omniauthable, :omniauth_providers => [:facebook]

• You'll need to set the callback url in facebook to your website/users/auth/facebook/callback
• You can add this line to the welcome view:

<%= link_to "Sign in with Facebook", user_facebook_omniauth_authorize_path %>

• Once this link is clicked, you'll need to add the following code to fix the error:

devise_for :users, :controllers => { :omniauth_callbacks => 'users/omniauth_callbacks' }

• Create a file in app/controllers/users/omniauth_callbacks_controller.rb

class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController
  def facebook
    @user = User.from_omniauth(request.env["omniauth.auth"])
    sign_in_and_redirect @user  
  end
end

# in the User model:
class User < ActiveRecord::Base
  def self.from_omniauth(auth)
    where(provider: auth.provider, uid: auth.uid).first_or_create do |user|
      user.email = auth.info.email
      user.password = Devise.friendly_token[0,20]
    end
  end
end

• the sign_in_and_redirect method, unfortunately doesn't tell devise where to redirect:

# in ApplicationController
def after_sign_in_path_for(resource)
  request.env['omniauth.origin'] || root_path
end

Editing Devise Views

• rails g devise:views
  • Installs views/devise to better customize forms