public void EditCategory(int id, Category newCategory)
 {
     if (newCategory == null)
     {
         throw new ServiceNullArgumentException("category was null");
     }
     try
     {
         categoryRepo.EditCategory(id, newCategory);
     }
     catch (DALException ex)
     {
         throw new ServiceException($"DAL exception : {ex.Message}");
     }
 }