SO: Adding StandingLineItem model

app/models/standing_line_item.rb

@@ -0,0 +1,8 @@
+class StandingLineItem < ActiveRecord::Base
+  belongs_to :standing_order
+  belongs_to :variant, class_name: 'Spree::Variant'
+
+  validates :standing_order, presence: true
+  validates :variant, presence: true
+  validates :quantity, { presence: true, numericality: { only_integer: true } }
+end

db/migrate/20160824013751_create_standing_line_items.rb

@@ -0,0 +1,16 @@
+class CreateStandingLineItems < ActiveRecord::Migration
+  def change
+    create_table :standing_line_items do |t|
+      t.references :standing_order, null: false
+      t.references :variant, null: false
+      t.integer :quantity, null: false
+      t.timestamps
+    end
+
+    add_index :standing_line_items, :standing_order_id
+    add_index :standing_line_items, :variant_id
+
+    add_foreign_key :standing_line_items, :standing_orders, name: 'oc_standing_line_items_standing_order_id_fk'
+    add_foreign_key :standing_line_items, :spree_variants, name: 'oc_standing_line_items_variant_id_fk', column: :variant_id
+  end
+end

db/schema.rb

@@ -1063,6 +1063,17 @@ ActiveRecord::Schema.define(:version => 20170921065259) do
     t.integer  "zone_members_count", :default => 0
   end
 
+  create_table "standing_line_items", :force => true do |t|
+    t.integer  "standing_order_id", :null => false
+    t.integer  "variant_id",        :null => false
+    t.integer  "quantity",          :null => false
+    t.datetime "created_at",        :null => false
+    t.datetime "updated_at",        :null => false
+  end
+
+  add_index "standing_line_items", ["standing_order_id"], :name => "index_standing_line_items_on_standing_order_id"
+  add_index "standing_line_items", ["variant_id"], :name => "index_standing_line_items_on_variant_id"
+
   create_table "standing_orders", :force => true do |t|
     t.integer  "shop_id",            :null => false
     t.integer  "customer_id",        :null => false
@@ -1309,6 +1320,9 @@ ActiveRecord::Schema.define(:version => 20170921065259) do
 
   add_foreign_key "spree_zone_members", "spree_zones", name: "spree_zone_members_zone_id_fk", column: "zone_id"
 
+  add_foreign_key "standing_line_items", "spree_variants", name: "oc_standing_line_items_variant_id_fk", column: "variant_id"
+  add_foreign_key "standing_line_items", "standing_orders", name: "oc_standing_line_items_standing_order_id_fk"
+
   add_foreign_key "standing_orders", "customers", name: "oc_standing_orders_customer_id_fk"
   add_foreign_key "standing_orders", "enterprises", name: "oc_standing_orders_shop_id_fk", column: "shop_id"
   add_foreign_key "standing_orders", "schedules", name: "oc_standing_orders_schedule_id_fk"

spec/models/standing_line_item_spec.rb

@@ -0,0 +1,17 @@
+require 'spec_helper'
+
+describe StandingLineItem, model: true do
+  describe "validations" do
+    it "requires a standing_order" do
+      expect(subject).to validate_presence_of :standing_order
+    end
+
+    it "requires a variant" do
+      expect(subject).to validate_presence_of :variant
+    end
+
+    it "requires a integer for quantity" do
+      expect(subject).to validate_numericality_of(:quantity).only_integer
+    end
+  end
+end

spec/models/standing_order_spec.rb

@@ -1,31 +1,29 @@
 require 'spec_helper'
 
 describe StandingOrder, type: :model do
-  let!(:standing_order) { create(:standing_order) }
-
   describe "validations" do
     it "requires a shop" do
-      expect(standing_order).to validate_presence_of :shop
+      expect(subject).to validate_presence_of :shop
     end
 
     it "requires a customer" do
-      expect(standing_order).to validate_presence_of :customer
+      expect(subject).to validate_presence_of :customer
     end
 
     it "requires a schedule" do
-      expect(standing_order).to validate_presence_of :schedule
+      expect(subject).to validate_presence_of :schedule
     end
 
     it "requires a payment_method" do
-      expect(standing_order).to validate_presence_of :payment_method
+      expect(subject).to validate_presence_of :payment_method
     end
 
     it "requires a shipping_method" do
-      expect(standing_order).to validate_presence_of :shipping_method
+      expect(subject).to validate_presence_of :shipping_method
     end
 
     it "requires a begins_at date" do
-      expect(standing_order).to validate_presence_of :begins_at
+      expect(subject).to validate_presence_of :begins_at
     end
   end
 end