Marketplace: Refactor to turn Checkout into a Command

#831

This "Demotes" `Checkout` from an Active Record and makes it serve more
as a Command object than a Domain Model. It's still ActiveModel'y so it
can be rendered using `render checkout` or routed to using `redirect_to
checkout.location`, but otherwise it's not holding any data or what not.

app/furniture/marketplace/cart.rb

@@ -1,30 +1,27 @@
 # frozen_string_literal: true
 
 class Marketplace
-  class Cart < ApplicationRecord
+  class Cart < Record
     self.table_name = "marketplace_carts"
-    include WithinLocation
     self.location_parent = :marketplace
 
+    default_scope { where(status: :pre_checkout) }
+
     belongs_to :marketplace, inverse_of: :carts
-    belongs_to :shopper, inverse_of: :carts
     delegate :space, :room, to: :marketplace
+
+    belongs_to :shopper, inverse_of: :carts
+
     has_many :cart_products, dependent: :destroy, inverse_of: :cart
     has_many :products, through: :cart_products, inverse_of: :carts
-    has_one :checkout, inverse_of: :cart
-    has_one :order, inverse_of: :cart
 
     enum status: {
       pre_checkout: "pre_checkout",
-      checked_out: "check_out"
+      paid: "paid"
     }
 
-    def self.model_name
-      @_model_name ||= ActiveModel::Name.new(self, ::Marketplace)
-    end
-
     def price_total
-      cart_products.sum do |cart_product|
+      cart_products.sum(0) do |cart_product|
         cart_product.product.price * cart_product.quantity
       end
     end

app/furniture/marketplace/cart_product.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class Marketplace
-  class CartProduct < ApplicationRecord
+  class CartProduct < Record
     self.table_name = "marketplace_cart_products"
 
     belongs_to :cart, inverse_of: :cart_products
@@ -14,14 +14,10 @@ class CartProduct < ApplicationRecord
 
     attribute :quantity, :integer, default: 0
 
-    def self.model_name
-      @_model_name ||= ActiveModel::Name.new(self, ::Marketplace)
-    end
-
     private
 
     def editable_cart
-      return unless cart&.checked_out?
+      return if cart&.pre_checkout?
 
       errors.add(:base, "Can't edit a checked-out cart!")
     end

app/furniture/marketplace/carts/_footer.html.erb

@@ -7,7 +7,7 @@
 <tfoot id="cart-footer-<%= cart.id%>" class="bg-gray-50">
   <tr>
     <td></td>
-    <th> <%= button_to("checkout", [space, room, marketplace, :checkouts], data: { turbo: false }) %> </th>
+    <th> <%= button_to("checkout", cart.location(child: :checkout), data: { turbo: false }) %> </th>
     <th scope="row" class="text-right px-1 py-3.5">Total: </th>
     <td class="text-left px-3 py-3.5 font-bold">
       <%= render "marketplace/carts/total", cart: cart %>

app/furniture/marketplace/checkout.rb

@@ -1,53 +1,41 @@
 class Marketplace
-  class Checkout < ApplicationRecord
-    self.table_name = "marketplace_checkouts"
-    include WithinLocation
-    self.location_parent = :marketplace
-
-    belongs_to :cart, inverse_of: :checkout
-    delegate :marketplace, to: :cart
-
-    has_many :ordered_products, through: :cart, source: :cart_products, class_name: "Marketplace::OrderedProduct"
-
-    belongs_to :shopper, inverse_of: :checkouts
+  class Checkout < Model
+    self.location_parent = :cart
+    include ActiveModel::Validations
+    attr_accessor :cart
+    delegate :shopper, :marketplace, to: :cart
 
     # It would be nice to validate instead the presence of :ordered_products, but my attempts at this raise:
     #  ActiveRecord::HasManyThroughCantAssociateThroughHasOneOrManyReflection:
     #   Cannot modify association 'Marketplace::Checkout#ordered_products' because the source reflection class 'CartProduct' is associated to 'Cart' via :has_many.
     validates :stripe_line_items, presence: true
 
-    enum status: {
-      pre_checkout: "pre_checkout",
-      paid: "paid"
-    }
-
-    def self.model_name
-      @_model_name ||= ActiveModel::Name.new(self, ::Marketplace)
-    end
-
     def create_stripe_session(success_url:, cancel_url:)
       Stripe::Checkout::Session.create({
         line_items: stripe_line_items,
         mode: "payment",
         success_url: success_url,
         cancel_url: cancel_url,
         payment_intent_data: {
-          transfer_group: id
+          transfer_group: cart.id
         }
       }, {
         api_key: marketplace.stripe_api_key
       })
     end
 
     def complete(stripe_session_id:)
-      update!(status: :paid, stripe_session_id: stripe_session_id)
-      cart.update!(status: :checked_out)
+      cart.update!(status: :paid, stripe_session_id: stripe_session_id)
+    end
+
+    def persisted?
+      true
     end
 
     private
 
     def stripe_line_items
-      return [] unless cart.present?
+      return [] if cart.blank?
 
       cart.cart_products.map do |cart_product|
         {

app/furniture/marketplace/checkouts_controller.rb

@@ -6,13 +6,13 @@ def show
         checkout.complete(stripe_session_id: params[:stripe_session_id])
         flash[:notice] = t(".success")
       end
-      redirect_to checkout.becomes(Order).location
+      redirect_to order.location
     end
 
     def create
       authorize(checkout)
 
-      if checkout.save
+      if checkout.valid?
         stripe_session = checkout.create_stripe_session(
           success_url: "#{polymorphic_url(checkout.location)}?stripe_session_id={CHECKOUT_SESSION_ID}",
           cancel_url: polymorphic_url(marketplace.location)
@@ -28,15 +28,19 @@ def create
     end
 
     helper_method def checkout
-      @checkout ||= if params[:id]
-        Checkout.find(params[:id])
+      @checkout ||= Checkout.new(cart: cart)
+    end
+
+    helper_method def cart
+      @cart ||= if params[:cart_id]
+        marketplace.carts.find(params[:cart_id])
       else
-        cart.checkout || cart.build_checkout(shopper: shopper)
+        marketplace.carts.find_or_create_by(shopper: shopper)
       end
     end
 
-    helper_method def cart
-      @cart ||= marketplace.carts.find_or_create_by(shopper: shopper, status: :pre_checkout)
+    def order
+      @order ||= cart.becomes(Order)
     end
   end
 end

app/furniture/marketplace/marketplace.rb

@@ -6,7 +6,7 @@ class Marketplace < FurniturePlacement
 
     has_many :products, inverse_of: :marketplace, dependent: :destroy
     has_many :carts, inverse_of: :marketplace, dependent: :destroy
-    has_many :orders, through: :carts
+    has_many :orders, inverse_of: :marketplace
 
     # The Secret Stripe API key belonging to the owner of the Marketplace
     def stripe_api_key=(key)

app/furniture/marketplace/model.rb

@@ -0,0 +1,10 @@
+class Marketplace
+  class Model
+    include ActiveModel::Model
+    include WithinLocation
+
+    def self.model_name
+      @_model_name ||= ActiveModel::Name.new(self, ::Marketplace)
+    end
+  end
+end

app/furniture/marketplace/order.rb

@@ -1,5 +1,24 @@
 class Marketplace
-  class Order < Checkout
+  class Order < Record
+    self.table_name = "marketplace_carts"
     self.location_parent = :marketplace
+
+    belongs_to :marketplace, inverse_of: :orders
+    delegate :space, :room, to: :marketplace
+
+    belongs_to :shopper, inverse_of: :orders
+
+    has_many :ordered_products, inverse_of: :order, foreign_key: :cart_id
+    has_many :products, through: :ordered_products, inverse_of: :orders
+
+    enum status: {
+      paid: "paid"
+    }
+
+    def price_total
+      ordered_products.sum(0) do |ordered_product|
+        ordered_product.product.price * ordered_product.quantity
+      end
+    end
   end
 end

app/furniture/marketplace/ordered_product.rb

@@ -1,8 +1,12 @@
 class Marketplace
-  class OrderedProduct < CartProduct
-    include WithinLocation
-    self.location_parent = :checkout
+  class OrderedProduct < Record
+    self.table_name = "marketplace_cart_products"
 
-    has_one :checkout, through: :cart
+    self.location_parent = :order
+
+    belongs_to :order, inverse_of: :ordered_products, foreign_key: :cart_id
+
+    belongs_to :product, inverse_of: :ordered_products
+    delegate :name, :description, :price, :price_cents, to: :product
   end
 end

app/furniture/marketplace/orders/_order.html.erb

@@ -23,7 +23,7 @@
         <td></td>
         <th scope="row" class="text-right px-1 py-3.5">Total: </th>
         <td class="text-left px-3 py-3.5 font-bold">
-          <%= render "marketplace/carts/total", cart: order.cart %>
+          <%= humanized_money_with_symbol(order.price_total) %>
         </td>
       </tr>
     </tfoot>

app/furniture/marketplace/product.rb

@@ -1,9 +1,8 @@
 # frozen_string_literal: true
 
 class Marketplace
-  class Product < ApplicationRecord
+  class Product < Record
     self.table_name = "marketplace_products"
-    include WithinLocation
     self.location_parent = :marketplace
 
     extend StripsNamespaceFromModelName
@@ -14,6 +13,9 @@ class Product < ApplicationRecord
     has_many :cart_products, inverse_of: :product, dependent: :destroy
     has_many :carts, through: :cart_products, inverse_of: :products
 
+    has_many :ordered_products, inverse_of: :product, dependent: :destroy
+    has_many :orders, through: :ordered_products, inverse_of: :products
+
     attribute :name, :string
     validates :name, presence: true
 

app/furniture/marketplace/record.rb

@@ -0,0 +1,9 @@
+class Marketplace
+  class Record < ApplicationRecord
+    self.abstract_class = true
+
+    def self.model_name
+      @_model_name ||= ActiveModel::Name.new(self, ::Marketplace)
+    end
+  end
+end

app/furniture/marketplace/routes.rb

@@ -6,8 +6,8 @@ def self.append_routes(router)
         router.resources :products
         router.resources :carts do
           router.resources :cart_products
+          router.resource :checkout, only: [:show, :create]
         end
-        router.resources :checkouts, only: [:show, :create]
       end
     end
   end

app/furniture/marketplace/shopper.rb

@@ -1,11 +1,11 @@
 # frozen_string_literal: true
 
 class Marketplace
-  class Shopper < ApplicationRecord
+  class Shopper < Record
     self.table_name = "marketplace_shoppers"
 
     belongs_to :person, optional: true
     has_many :carts, inverse_of: :shopper
-    has_many :checkouts, inverse_of: :shopper
+    has_many :orders, inverse_of: :shopper
   end
 end

app/models/application_record.rb

@@ -1,3 +1,4 @@
 class ApplicationRecord < ActiveRecord::Base
   self.abstract_class = true
+  include WithinLocation
 end

db/migrate/20230120234526_drop_checkouts_table.rb

@@ -0,0 +1,16 @@
+class DropCheckoutsTable < ActiveRecord::Migration[7.0]
+  def change
+    drop_table "marketplace_checkouts", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
+      t.uuid "cart_id"
+      t.uuid "shopper_id"
+      t.datetime "created_at", null: false
+      t.datetime "updated_at", null: false
+      t.string "status", default: "pre_checkout", null: false
+      t.string "stripe_session_id"
+      t.index ["cart_id"], name: "index_marketplace_checkouts_on_cart_id"
+      t.index ["shopper_id"], name: "index_marketplace_checkouts_on_shopper_id"
+    end
+
+    add_column "marketplace_carts", :stripe_session_id, :string
+  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[7.0].define(version: 2023_01_19_014621) do
+ActiveRecord::Schema[7.0].define(version: 2023_01_20_234526) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pgcrypto"
   enable_extension "plpgsql"
@@ -22,12 +22,12 @@
     "expired",
     "ignored",
     "revoked",
-    "sent",
+    "sent"
   ], force: :cascade
 
   create_enum :membership_status, [
     "active",
-    "revoked",
+    "revoked"
   ], force: :cascade
 
   create_table "active_storage_attachments", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
@@ -140,21 +140,11 @@
     t.datetime "updated_at", null: false
     t.uuid "shopper_id"
     t.string "status", default: "pre_checkout", null: false
+    t.string "stripe_session_id"
     t.index ["marketplace_id"], name: "index_marketplace_carts_on_marketplace_id"
     t.index ["shopper_id"], name: "index_marketplace_carts_on_shopper_id"
   end
 
-  create_table "marketplace_checkouts", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
-    t.uuid "cart_id"
-    t.uuid "shopper_id"
-    t.datetime "created_at", null: false
-    t.datetime "updated_at", null: false
-    t.string "status", default: "pre_checkout", null: false
-    t.string "stripe_session_id"
-    t.index ["cart_id"], name: "index_marketplace_checkouts_on_cart_id"
-    t.index ["shopper_id"], name: "index_marketplace_checkouts_on_shopper_id"
-  end
-
   create_table "marketplace_products", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|
     t.uuid "marketplace_id"
     t.string "name"

spec/factories/marketplace/checkouts.rb

@@ -1,19 +1,13 @@
 FactoryBot.define do
   factory :marketplace_checkout, class: "Marketplace::Checkout" do
-    trait :with_shopper do
-      transient do
-        person { nil }
-      end
-
-      shopper { build(:marketplace_shopper, person: person) }
-    end
-
     trait :with_cart do
       transient do
         marketplace { nil }
+        person { nil }
       end
-      before(:build) do |checkout, evaluator|
-        build(:marketplace_cart, marketplace: marketplace, checkout: checkout, shopper: checkout.shopper)
+      after(:build) do |checkout, evaluator|
+        shopper = build(:marketplace_shopper, person: evaluator.person)
+        checkout.cart = build(:marketplace_cart, marketplace: evaluator.marketplace, shopper: shopper)
       end
     end
   end