shopping cart

app/controllers/books_controller.rb

@@ -1,5 +1,5 @@
 class BooksController < ApplicationController
-  before_action :set_book, only: [:show, :edit, :update]
+  before_action :set_book, only: [:show, :edit, :update, :add_to_cart]
   before_action :ensure_admin, only: [:edit, :update]
 
   def index
@@ -23,6 +23,17 @@ class BooksController < ApplicationController
     end
   end
 
+  def add_to_cart
+    @book = Book.find(params[:id])
+    current_user.books << @book
+    @book.decrement!(:quantity)
+    redirect_to '/books', notice: 'Book added to your cart'
+  end
+
+  def shopping_cart
+    @books = current_user.books.map { |book| BooksPresenter.new(book) }
+  end
+
   private
 
   def set_book

app/models/application_record.rb

@@ -15,4 +15,9 @@ class ApplicationRecord < ActiveRecord::Base
     AuditRecord.create(model: self.class, action: 'create', params: result.to_json)
     result
   end
+  def decrement!(*args)
+    result = super(*args)
+    AuditRecord.create(model: self.class, action: 'decrement!', params: self.to_json)
+    result
+  end
 end

app/models/user.rb

@@ -1,4 +1,6 @@
 class User < ApplicationRecord
+  has_and_belongs_to_many :books
+
   has_secure_password
   has_secure_password :recovery_password, validations: false
   enum role: [:customer, :admin], _default: :customer

app/views/books/index.html.erb

@@ -24,8 +24,8 @@
         <%= book.quantity %>
       </div>
       <div class='col s2'>
-        <% if logged_in? && book.quantity.positive? %>
-          <%= link_to 'Add', edit_book_path(book), class: "btn" %>
+        <% if logged_in? && book.quantity.positive? && !current_user.books.exists?(book.id) %>
+          <%= link_to 'Add', "book/#{book.id}/add_to_cart", method: :post, class: "btn" %>
         <% end %>
       </div>
 

app/views/books/shopping_cart.erb

@@ -0,0 +1,22 @@
+<div class='container'>
+  <div class='row'>
+    <div class='col s2'>Title</div>
+    <div class='col s3'>Authors</div>
+    <div class='col s1'>Price</div>
+  </div>
+  <% @books.each do |book| %>
+    <div class='row'>
+      <div class='col s2'>
+        <%= link_to book.title, book %>
+      </div>
+
+      <div class='col s3'>
+        <%= book.authors %>
+      </div>
+
+      <div class='col s1'>
+        <%= book.price_with_currency %>
+      </div>
+    </div>
+  <% end %>
+</div>

app/views/layouts/application.html.erb

@@ -32,7 +32,7 @@
           <% end %>
           <% if logged_in? %>
             <div class='col s2'>
-              <%= link_to 'Shopping cart', '/authors', method: :get%>
+              <%= link_to 'Shopping cart', '/shopping_cart', method: :get%>
             </div>
           <% end %>
         </div>