public static void UpdateItem(APISalesOnlinePrinciple postedItem)
        {
            var editedModel = SalesOnlinePrincipleList.GetData().First(i => i.ID == postedItem.ID);

            editedModel.DebitAccount       = postedItem.DebitAccount;
            editedModel.DebitPostingActor  = postedItem.DebitPostingActor;
            editedModel.CreditAccount      = postedItem.CreditAccount;
            editedModel.CreditPostingActor = postedItem.CreditPostingActor;
            editedModel.Amount             = postedItem.Amount;
            editedModel.Description        = postedItem.Description;
        }
 public static void AddItem(APISalesOnlinePrinciple postedItem)
 {
     SalesOnlinePrincipleList.GetData().Add(postedItem);
 }