Simple Authentication in Rail 4 Using Bcrypt

#Simple Authentication with Bcrypt

This tutorial is for adding authentication to a vanilla Ruby on Rails app using Bcrypt and has_secure_password.

The steps below are based on Ryan Bates's approach from Railscast #250 Authentication from Scratch (revised).

You can see the final source code here: repo. I began with a stock rails app using rails new gif_vault

##Steps

Create a user model with a name, email and password_digest (all strings) by entering the following command into the command line: rails generate model user name email password_digest.

Note: If you already have a user model or you're going to use a different model for authentication, that model must have an attribute names password_digest and some kind of attribute to identify the user (like an email or a username).
Run rake db:migrate in the command line to migrate the database.

Add these routes below to your routes.rb file. Notice I also deleted all the comments inside that file. Don't forget to leave the trailing end, though.

# config/routes.rb

GifVault::Application.routes.draw do
    
    # This route sends requests to our naked url to the *cool* action in the *gif* controller.
    root to: 'gif#cool'
    
    # I've created a gif controller so I have a page I can secure later. 
    # This is optional (as is the root to: above).
    get '/cool' => 'gif#cool'
    get '/sweet' => 'gif#sweet'

    # These routes will be for signup. The first renders a form in the browse, the second will 
    # receive the form and create a user in our database using the data given to us by the user.
    get '/signup' => 'users#new'
    post '/users' => 'users#create'

end

Create a users controller:

# app/controllers/users_controller.rb

class UsersController < ApplicationController

end

Add a new action (for rendering the signup form) and a create action (for receiving the form and creating a user with the form's parameters.):

# app/controllers/users_controller.rb

class UsersController < ApplicationController

    def new
    end

    def create
    end   

end

Now create the view file where we put the signup form.
```


<h1>Signup!</h1>

<%= form_for :user, url: '/users' do |f| %>

  Name: <%= f.text_field :name %>
  Email: <%= f.text_field :email %>
  Password: <%= f.password_field :password %>
  Password Confirmation: <%= f.password_field :password_confirmation %>
  <%= f.submit "Submit" %>

<% end %>
```
A note on Rail's conventions: This view file is for the new action of the users controller. As a result, we save the file here: /app/views/users/new.html.erb. The file is called new.html.erb and it is saved inside the views folder, in a folder we created called users.

That's the convention: view files are inside a folder with the same name as the controller and are named for the action they render.
Add logic to create action and add the private user_params method to sanitize the input from the form (this is a new Rails 4 thing and it's required). You might need to adjust the parameters inside the .permit() method based on how you setup your User model.

class UsersController < ApplicationController

def new
end

def create
  user = User.new(user_params)
  if user.save
    session[:user_id] = user.id
    redirect_to '/'
  else
    redirect_to '/signup'
  end
end

private

def user_params
  params.require(:user).permit(:name, :email, :password, :password_confirmation)
end

end ```

Go to your Gemfile and uncomment the 'bcrypt' gem. We need bcrypt to securely store passwords in our database.

source 'https://rubygems.org'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.0.4'

# Use sqlite3 as the database for Active Record
gem 'sqlite3'

...

# Use ActiveModel has_secure_password
gem 'bcrypt', '~> 3.1.7'

...

Go to the User model file and add has_secure_password. This is the line of code that gives our User model authentication methods via bcrypt.
```
# app/models/user.rb
    
class User < ActiveRecord::Base

  has_secure_password

end
```
Run bundle install from the terminal then restart your rails server.

Note: Windows users might have issues with bcrypt. If so, copy the error into Google and look for answers on Stack Overflow. There is documentation online for how to fix Windows so the bcrypt works.

Create a sessions controller. This is where we create (aka login) and destroy (aka logout) sessions.

# app/controllers/sessions_controller.rb

class SessionsController < ApplicationController

  def new
  end

  def create
  end

  def destroy
  end

end

Create a form for user's to login with.

<!-- app/views/sessions/new.html.erb -->

<h1>Login</h1>

<%= form_tag '/login' do %>

  Email: <%= text_field_tag :email %>
  Password: <%= password_field_tag :password %>
  <%= submit_tag "Submit" %>

<% end %>

Update your routes file to include new routes for the sessions controller.

GifVault::Application.routes.draw do

  root to: 'gif#cool'

  # these routes are for showing users a login form, logging them in, and logging them out.
  get '/login' => 'sessions#new'
  post '/login' => 'sessions#create'
  get '/logout' => 'sessions#destroy'

  get '/signup' => 'users#new'
  post '/users' => 'users#create'
  
end

Update the sessions_controller with the logic to log users in and out.

  # app/controllers/sessions_controller.rb

  def create
    user = User.find_by_email(params[:email])
    # If the user exists AND the password entered is correct.
    if user && user.authenticate(params[:password])
      # Save the user id inside the browser cookie. This is how we keep the user 
      # logged in when they navigate around our website.
      session[:user_id] = user.id
      redirect_to '/'
    else
    # If user's login doesn't work, send them back to the login form.
      redirect_to '/login'
    end
  end

  def destroy
    session[:user_id] = nil
    redirect_to '/login'
  end

Update the application controller with new methods to look up the user, if they're logged in, and save their user object to a variable called @current_user. The helper_method line below current_user allows us to use @current_user in our view files. Authorize is for sending someone to the login page if they aren't logged in - this is how we keep certain pages our site secure... user's have to login before seeing them.

# app/controllers/application_controller.rb

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception

  def current_user
    @current_user ||= User.find(session[:user_id]) if session[:user_id]
  end
  helper_method :current_user

  def authorize
    redirect_to '/login' unless current_user
  end

end

Add a before_filter to any controller that you want to secure. This will force user's to login before they can see the actions in this controller. I've created a gif controller below which I'm going to secure. The routes for this controller were added to the routes.rb in the beginning of this tutorial.
```
# app/controllers/gif_controller.rb

class GifController < ApplicationController

  before_filter :authorize

  def cool
  end

  def free
  end

end
```

You can update your application layout file to show the user's name if they're logged in and some contextual links.

<!-- app/views/layout/application.html.erb -->

<!DOCTYPE html>
<html>
<head>
  <title>GifVault</title>
  <%= stylesheet_link_tag    "application", media: "all", "data-turbolinks-track" => true %>
  <%= javascript_include_tag "application", "data-turbolinks-track" => true %>
  <%= csrf_meta_tags %>
</head>
<body>

# added these lines.
<% if current_user %>
  Signed in as <%= current_user.name %> | <%= link_to "Logout", '/logout' %>
<% else %>
  <%= link_to 'Login', '/login' %> | <%= link_to 'Signup', '/signup' %>
<% end %>

<%= yield %>

</body>
</html>

##Things Missing

Adding flash messages would be simple and provide feedback to the user if things go wrong.

-- All done! Feel free to fork and update this. Reach me at @thebucknerlife on Twitter.

b-ggs/authentication_with_bcrypt_in_rails_4.md