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>

config/routes.rb

@@ -9,6 +9,9 @@ Rails.application.routes.draw do
   get 'recover_password/:id/:recovery_password', to: 'users#recover_password_form'
   post 'recover_password', to: 'users#recover_password'
   post 'user/:id/block', to: 'users#block'
+  post 'book/:id/add_to_cart', to: 'books#add_to_cart'
+  get 'shopping_cart', to: 'books#shopping_cart'
+
   resources :books
   resources :authors
 end

db/migrate/20210322002803_create_books_users.rb

@@ -0,0 +1,10 @@
+class CreateBooksUsers < ActiveRecord::Migration[6.1]
+  def change
+    create_table :books_users do |t|
+      t.belongs_to :book
+      t.belongs_to :user
+
+      t.timestamps
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2021_03_21_235625) do
+ActiveRecord::Schema.define(version: 2021_03_22_002803) do
 
   create_table "audit_records", force: :cascade do |t|
     t.string "model"
@@ -47,6 +47,15 @@ ActiveRecord::Schema.define(version: 2021_03_21_235625) do
     t.index ["published"], name: "index_books_on_published"
   end
 
+  create_table "books_users", force: :cascade do |t|
+    t.integer "book_id"
+    t.integer "user_id"
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+    t.index ["book_id"], name: "index_books_users_on_book_id"
+    t.index ["user_id"], name: "index_books_users_on_user_id"
+  end
+
   create_table "users", force: :cascade do |t|
     t.string "email"
     t.string "password_digest"

db/seeds.rb

@@ -15,7 +15,13 @@ books = Book.create([
     title: 'Imaginary trip',
     price: 3600,
     published: true,
-    quantity: 0
+    quantity: 1
+  },
+  {
+    title: 'Winnie the Pooh',
+    price: 3700,
+    published: true,
+    quantity: 5
   },
 ])
 
@@ -32,12 +38,17 @@ authors = Author.create([
     first_name: 'Rick',
     last_name: 'Pickle'
   },
+  {
+    first_name: 'Alan',
+    last_name: 'Milne'
+  },
 ])
 
 books.first.authors << authors.first
 books.second.authors << authors.first
 books.third.authors << authors.second
 books.third.authors << authors.third
+books.fourth.authors << authors.fourth
 
 User.create([
   {

spec/models/audit_record_spec.rb

@@ -1,5 +0,0 @@
-require 'rails_helper'
-
-RSpec.describe AuditRecord, type: :model do
-  pending "add some examples to (or delete) #{__FILE__}"
-end