Improve order about amount & product_amount & product_original_amount

lib/generators/templates/views/share/_merchant_order.json.jbuilder

-json.extract! order, :id, :seq, :address,
+json.extract! order, :id, :seq, :address, :amount,
+  :product_amount, :product_original_amount, 
   :total_price, :total_original_price, 
   :pay_time, :delivery_time, :receipt_time, 
   :delivery_way, :delivery_cost, 

lib/generators/templates/views/share/_merchant_order_simple.json.jbuilder

-json.extract! order, :id, :seq, :address,
-  :total_price, :total_original_price, 
+json.extract! order, :id, :seq, :address, :amount
+  :product_amount, :product_original_amount, 
   :pay_time, :delivery_time, :receipt_time, 
   :delivery_way, :delivery_cost, 
   :merchant_remark, :mark, :customer_remark, 

lib/generators/templates/views/share/_order.json.jbuilder

-json.extract! order, :id, :seq, :total_price, :total_original_price, 
+json.extract! order, :id, :seq, :amount,
+  :product_amount, :product_original_amount, 
   :status_zh, :address,
   :pay_time, :delivery_time, :receipt_time, 
   :delivery_way, :delivery_cost, :customer_remark, 

lib/generators/templates/views/share/_order_simple.json.jbuilder

-json.extract! order, :id, :seq, :address, 
-  :total_price, :total_original_price, 
+json.extract! order, :id, :seq, :address, :amount,
+  :product_amount, :product_original_amount, 
   :pay_time, :delivery_time, :receipt_time, 
   :delivery_way, :delivery_cost, :customer_remark, 
   :status, :status_zh, :meta, :created_at
\ No newline at end of file

lib/shotengai/order.rb

@@ -98,10 +98,6 @@ module Shotengai
       update!(receipt_time: Time.now)
     end
 
-    def set_amount
-      self.update!(amount: product_amount + delivery_cost)
-    end
-
     def set_seq
       timestamp = Time.now.strftime("%Y%m%d-%H%M")
       no_length = 4
@@ -109,6 +105,14 @@ module Shotengai
       self.update!(seq: "#{timestamp}-#{no}}")
     end
 
+    def set_amount
+      self.update!(amount: product_amount + delivery_cost)
+    end
+    
+    def amount
+      read_attribute(:amount) || product_amount + delivery_cost
+    end
+    
     def product_amount
       snapshots.sum(&:total_price)
     end
@@ -117,6 +121,8 @@ module Shotengai
       snapshots.sum(&:total_original_price)
     end
 
+
+    
     # into order
     def incr_snapshot_ids= ids
       ActiveRecord::Base.transaction do