Add scope :in_order & :in_cart to Snapshot

lib/shotengai/cart.rb

@@ -28,7 +28,13 @@ module Shotengai
   class Cart < ::ActiveRecord::Base
     self.table_name = 'shotengai_orders'
     default_scope { where(status: 'cart') } 
-
+    #
+    #  class Order < Shotengai::Order
+    #     can_by 'Product'
+    #  end
+    #
+    #  Would let Product belongs to :order & order_cart
+    # 
     class << self
       def can_buy *good_class_names
         good_classes = good_class_names.map { |name| Object.const_get(name) }

lib/shotengai/order.rb

@@ -30,7 +30,8 @@ module Shotengai
   
   class Order < ActiveRecord::Base
     self.table_name = 'shotengai_orders'
-    belongs_to :buyer, polymorphic: true
+    belongs_to :buyer, polymorphic: true, optional: true
+    
     default_scope { where.not(status: 'cart') } 
 
     include AASM_DLC

lib/shotengai/snapshot.rb

@@ -31,7 +31,23 @@ module Shotengai
     validate :check_spec, if: :spec
     validates :count, numericality: { only_integer: true, greater_than: 0 }
 
-    belongs_to :shotengai_order, optional: true
+    belongs_to :shotengai_order, foreign_key: :shotengai_order_id, 
+      class_name: 'Shotengai::Order', optional: true
+    
+    scope :in_order, ->{ 
+      joins("
+        INNER JOIN shotengai_orders ON 
+          shotengai_snapshots.shotengai_order_id = shotengai_orders.id AND 
+          shotengai_orders.status <> 'cart'
+      ")
+    }
+    scope :in_cart, ->{ 
+      joins("
+        INNER JOIN shotengai_orders ON 
+          shotengai_snapshots.shotengai_order_id = shotengai_orders.id AND 
+          shotengai_orders.status = 'cart'
+      ")
+    }
 
     class << self
       def inherited subclass