test sum

app/models/cash_balance.rb

@@ -42,11 +42,11 @@ class CashBalance < ActiveRecord::Base
     end
   end
   @total=0
-  @list=[]
+  list=[]
   def get_happen_total
-    @list.append(self.id)
+    list.append(self.id)
 
-    total =  CashBalance.where(id: @list).sum("count")
+    total =  CashBalance.where(id: list).sum("count")
 
     return total
   end