tutorial.md

#Simple Authentication with Bcrypt in Rails 5

This tutorial is for adding authentication to a vanilla Ruby on Rails app using Bcrypt and has_secure_password. It is based on Ryan Bates's approach from Railscast #250 Authentication from Scratch (revised) and a gist by thebucknerlife (@thebucknerlife on Twitter).

For an example, see a WDI lab solution implementing auth in Rails.

##Steps

1. 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 named password_digest and some kind of attribute to identify the user (like an email or a username).

2. Run rake db:migrate in the command line to migrate the database.

3. Add the routes below to your config/routes.rb file.

   # config/routes.rb
   
   GifVault::Application.routes.draw do
   
       # These routes will be for signup. The first renders a form in the browser. 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

4. Create a users controller:

   # app/controllers/users_controller.rb
   
   class UsersController < ApplicationController
   
   end

5. 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

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

   <!-- app/views/users/new.html.erb -->
   
   <h1>Sign up!</h1>
   
   <%= form_for :user, url: '/users' do |f| %>
   
     Name: <%= f.text_field :name %><br>
     Email: <%= f.text_field :email %><br>
     Password: <%= f.password_field :password %><br>
     Password Confirmation: <%= f.password_field :password_confirmation %><br>
     <%= 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.

7. Add logic to create action and add the private user_params method to ensure we're only using intended input parameters from the form. You will need to adjust the parameters inside the .permit() method based on how you set up your User model - be sure to permit all the fields you expect to receive from your front end.

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 ```

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

   source 'https://rubygems.org'
   
   # ...
   
   # Use ActiveModel has_secure_password
   gem 'bcrypt'
   
   # ...

8. 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

   See has_secure_password's documentation and source code.

9. Run bundle install from the terminal, and then restart your rails server.

10. Create a sessions controller. This is where we create and destroy sessions (aka log in / log out).

    # app/controllers/sessions_controller.rb
    
    class SessionsController < ApplicationController
    
      def new
      end
    
      def create
      end
    
      def destroy
      end
    
    end

11. Create a form for users to log in 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 %>

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

    GifVault::Application.routes.draw do
    
      # ...
    
      # 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

13. 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

14. 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

15. 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

16. 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>

-- All done!