order_static add if nil

app/models/order_static_detail.rb

@@ -6,10 +6,14 @@ class OrderStaticDetail < ActiveRecord::Base
 
   STATUS_ENUM = [["处理中,已完成,待收货",""],["未支付","unpay"],["已关闭","closed"],["待确认","unconfirmed"],["处理中","processing"],["已完成","complete"],["待收货","dispatch"],["已退款","refunded"]]
   def begin_date_fomat
-    return self.begin_date.strftime
+    if !self.begin_date.nil?
+      return self.begin_date.strftime
+    end
   end
   def end_date_fomat
-    return self.end_date.strftime
+    if !self.end_date.nil?
+      return self.end_date.strftime
+    end
   end
   rails_admin do
     navigation_label '销售汇总明细'