Set default val to meta

lib/shotengai/order.rb

@@ -124,6 +124,10 @@ module Shotengai
       end
     end
 
+    def meta
+      super || {}
+    end
+    
     class << self
       def inherited subclass
         # define Cart class

lib/shotengai/product.rb

@@ -63,6 +63,10 @@ module Shotengai
       Shotengai::Series.find_by_id(default_series_id) || series.first
     end
 
+    def meta
+      super || {}
+    end
+
     class << self
       def series_class
         Shotengai::Series

lib/shotengai/series.rb

@@ -30,7 +30,7 @@ module Shotengai
     
     delegate :title, :detail, :banners, :cover_image, :status, :status_zh, to: :product
     
-    # where(spec->'$.\"颜色\"' = ?  and spec->'$.\"大小\"' = ? ,红色,S)
+    # where("spec->'$.\"颜色\"' = ?  and spec->'$.\"大小\"' = ?" ,红色,S)
     scope :query_spec_with_product, ->(val, product) { 
       if val.keys.sort == product.spec.keys.sort 
         keys = []; values = []
@@ -72,6 +72,10 @@ module Shotengai
       read_attribute(:original_price) || price
     end
 
+    def meta
+      super || {}
+    end
+
     private 
       # spec 字段
       def check_spec_value

lib/shotengai/snapshot.rb

@@ -120,6 +120,10 @@ module Shotengai
 
     ######
     
+    def meta
+      super || {}
+    end
+
     private 
       # spec 字段
       def check_spec