AR Breakout

breakout.rb

require 'pry'
require 'active_record'

ActiveRecord::Base.logger = Logger.new(STDOUT)

# Objects that we will be using

class Customer < ActiveRecord::Base
  has_many :invoices

  validates :first_name, presence: true
  validates :last_name,  presence: true
  validates :email,      presence: true,
                         uniqueness: true,
                         format: /\A([\w+\-].?)+@[a-z\d\-]+(\.[a-z]+)*\.[a-z]+\z/i

  before_validation { self.email = email.downcase }

  def self.find_by_email(email)
    find_by(email: email.downcase)
  end

  def name
    "#{first_name} #{last_name}"
  end
end

class Product < ActiveRecord::Base
  #has_and_belongs_to_many :invoices #for pure many-to-many relationship
  has_many :invoice_items
  has_many :invoices, through: :invoice_items # many-to-many relations using an itermediate table

  validates :name,        presence: true
  validates :description, presence: true
  validates :price_cents, numericality: { only_integer: true, greater_than_or_equal_to: 0 }
  validates :inventory,   numericality: { only_integer: true, greater_than_or_equal_to: 0 }
end

class Invoice < ActiveRecord::Base
  belongs_to :customer
  belongs_to :shipping_address, class_name: 'Address'
  belongs_to :billing_address, class_name: 'Address'

  has_many :invoice_items, autosave: true
  has_many :products, through: :invoice_items # many-to-many relations using an itermediate table

  def total_price
    invoice_items.reduce(0) { |total, x| total + x.price_cents }
  end
end

class InvoiceItem < ActiveRecord::Base
  belongs_to :invoice
  belongs_to :product

  after_create :update_inventory

  private

  def update_inventory
    product_inventory = product.inventory
    product.update(inventory: product_inventory - quantity)
  end
end

class Address < ActiveRecord::Base
  belongs_to :customer
end

puts "Establishing connection to Database"
ActiveRecord::Base.establish_connection(
  adapter: 'postgresql',
  database: 'ar_breakout',
  username: 'rob',
  encoding: 'unicode'
)

puts "Creating DB Schema"
ActiveRecord::Schema.define do
  drop_table :customers if ActiveRecord::Base.connection.table_exists?(:customers)
  drop_table :invoices if ActiveRecord::Base.connection.table_exists?(:invoices)
  drop_table :invoice_items if ActiveRecord::Base.connection.table_exists?(:invoice_items)
  drop_table :products if ActiveRecord::Base.connection.table_exists?(:products)
  drop_table :invoices_products if ActiveRecord::Base.connection.table_exists?(:invoices_products)

  create_table :customers do |t|
    t.string :first_name,  null: false
    t.string :last_name,   null: false
    t.string :email,       null: false, index: true, unique: true
  end

  create_table :products do |t|
    t.string  :name,        null: false
    t.integer :inventory,   null: false, default: 0
    t.text    :description, null: false, default: ''
    t.integer :price_cents, null: false, default: 0
  end

  create_table :addresses do |t|
    t.references :customer
    t.string :address_1
    t.string :city
  end

  create_table :invoices do |t|
    t.references :customer, index: true, foreign: true
    t.datetime :invoice_date, null: false
    t.references :shipping_address
    t.references :billing_address
  end

  # needed for a pure many-to-many relationship
  create_table :invoices_products do |t|
    t.references :product
    t.references :invoice
  end

  create_table :invoice_items do |t|
    t.references :product
    t.references :invoice
    t.integer :price_cents
    t.integer :quantity
  end
end

puts "SEED Database"

Customer.create!(first_name: 'Jane', last_name: 'Doe', email: '[email protected]')
Customer.create!(first_name: 'John', last_name: 'Smith', email: '[email protected]')

Product.create!(name: 'Beer', description: 'Best drink in the world', price_cents: 290,    inventory: 100)
Product.create!(name: 'Whiskey', description: 'The Scottish like it', price_cents: 100000, inventory: 50)
customer.invoices.create!(invoice_date: DateTime.now)
customer.invoices.create!(invoice_date: 1.month.ago)

puts "Running class code"

customer = Customer.find_by_email('[email protected]')

# Creating an Invoice with 1 item related to a product
product = Product.first
invoice = customer.invoices.build(invoice_date: DateTime.now)
item = invoice.invoice_items.build(product: product, price_cents: product.price_cents, quantity: 2)
invoice.save

# after the invoice is save the inventory of the product should decrease by two
# <model>.reload reloads the model (ie syncs) from the DB (used a lot in testing)
product.reload.inventory == product.inventory - item.quantity