# How to call a domain logic function inside pre-condition?

1. Define a reference variable to the domain logic inside the command-set.

   
   

    

   
   
   
   

   command-set Lottery {
   	domain-logic-ref lotteryDomainLogicRef:Lottery
     ...
   }
   

2. Call the respective domain function using the reference variable inside the pre condition

   
   
   
   
   
   

    

   
   
   
   
   
   
   

   command-set Lottery {
   	domain-logic-ref lotteryDomainLogicRef:Lottery
     command create{
         input(lotteryName:String,amount:Int)
         pre{
           condition NewLotteryName => !(lotteryDomainLogicRef.lotteryNameExists(input.lotteryName)) failing "Lottery Name Already Exists !"
           ...
         }
         ...
   	}
   }