HowToSetup Mapping

creating.cs

public static tbl_Loss ToTblLoss(ImportLoss importLoss)
{
   var retVal = new tbl_Loss {
      dat_dateOfClaim = importLoss.DateOfLoss,
      txt_claimant = importLoss.Claimant,
      lok_policy = _helper.FindPolicyFromPolicyNumber(impotLoss.PolicyNumber).aut_id,
   };
   return retVal;
}

HelperClass.cs

public  class HelperClass  // Rename me
{
    private  Dictionary<string,tbl_Policy> PolicyCache = new Dictionary<string,tbl_Policy>();
    private  Dictionary<string,tbl_Client> ClientCache = new Dictionary<string,tbl_Client>();
    public  tbl_Policy FindPolicyFromPolicyNumber(string policyNumber) 
    {
       if (PolicyCache.ContainsKey(policyNumber)) {
         return PolicyCache[policyNumber];
       }
       var pol = ctx.tbl_Policy.Include("tbl_Client").Single(f => f.txt_policyNumber == policyNumber);
       PolicyCache.Add(policyNumber, pol);
       ClientCache.Add(policyNumber, pol.tbl_Client);
       return pol;
    }
    
    public  tbl_Client FindPolicyFromPolicyNumber(string policyNumber) 
    {
       if (ClientCache.ContainsKey(policyNumber)) {
         return ClientCache[policyNumber];
       }
       var client = ctx.tbl_Client.Single(f => f.tbl_Policy.Any(g => g.txt_policyNumber == policyNumber));
       ClientCache.Add(policyNumber, client);
       return client;
    }
}