增加订单导入功能

app/models/order.rb

@@ -30,12 +30,16 @@ class Order < ActiveRecord::Base
     end
 
     def before_save
-        if self.express_company.length>0
-            express = ExpressCompany.where("express_company = ?", self.express_company).first
-            if !express.blank?
-                self.express_code = express.express_code
+
+        unless  self.express_company.nil?
+            if self.express_company.length>0
+                express = ExpressCompany.where("express_company = ?", self.express_company).first
+                if !express.blank?
+                    self.express_code = express.express_code
+                end
             end
         end
+
         if !self.wx_user.blank?
             self.errors.add("微信ID不存在")
         end