public with sharing class TruncateId {
    public TruncateId() {

    }

    @InvocableMethod(label='Truncate ID' description='Transaction Id on Opportunity Object' category='Opportunity')
    public static void Truncate(List<Opportunity> OppIds){

        ID oppID = OppIds[0].id;

        Opportunity opp = [SELECT id, TranscationId__c, name FROM Opportunity WHERE id = :oppID];

      
        String last6 = opp.TranscationId__c.right(6);
        if(opp.TranscationId__c != null){    
            if(last6 != opp.Name.right(6)){
                opp.name = opp.name + last6;
                update  opp;
            }
        }
      

    }

    public class GetOppId{
        @InvocableVariable(required=true label='Opportunity Id')
        public ID oppID;

    }

}