Rails provides various ways of implementing authentication and authorization. But the simplest one is a new module, which has been added in Rails 2.0. This module is a great way to do API authentication over SSL.

To use this authentication, you will need to use SSL for traffic transportation. In our tutorial, we are going to test it without an SSL.

Let us start with our library example that we have discussed throughout the tutorial. We do not have much to do to implement authentication. We will add a few lines in blue in our ~library/app/controllers/book_controller.rb:

Finally, your book_controller.rb file will look as follows −

class BookController < ApplicationController

USER_ID, PASSWORD = "zara", "pass123"
 
# Require authentication only for edit and delete operation
   before_filter :authenticate, :only => [ :edit, :delete ]
  
def list
   @books = Book.find(:all)
end
   
def show
   @book = Book.find(params[:id])
end
   
def new
   @book = Book.new
   @subjects = Subject.find(:all)
end
   
def create
   @book = Book.new(params[:book])
   if @book.save
      redirect_to :action => ''list''
   else
      @subjects = Subject.find(:all)
      render :action => ''new''
   end
end
   
def edit
   @book = Book.find(params[:id])
   @subjects = Subject.find(:all)
end
   
def update
   @book = Book.find(params[:id])
   if @book.update_attributes(params[:book])
      redirect_to :action => ''show'', :id => @book
   else
      @subjects = Subject.find(:all)
      render :action => ''edit''
   end
end
   
def delete
   Book.find(params[:id]).destroy
   redirect_to :action => ''list''
end
   
def show_subjects
   @subject = Subject.find(params[:id])
end
   
private
   def authenticate
      authenticate_or_request_with_http_basic do |id, password| 
         id == USER_ID && password == PASSWORD
      end
   end
end

Let us explain these new lines −

• The first line is just to define the user ID and password to access various pages.

• In the second line, we have put before_filter, which is used to run the configured method authenticate before any action in the controller. A filter may be limited to specific actions by declaring the actions to include or exclude. Both options accept single actions (:only => :index) or arrays of actions (:except => [:foo, :bar]). So here we have put authentication for edit and delete operations only.

• Due to the second line, whenever you would try to edit or delete a book record, it will execute private authenticate method.

• A private authenticate method is calling uthenticate_or_request_with_http_basic method, which comprises of a block and displays a dialogue box to ask for User ID and Password to proceed. If you enter a correct user ID and password then it will proceed, otherwise it would display ‘access denied’.

Now, try to edit or delete any available record, to do so you would have to go through the authentication process using the following dialogue box.