public long GetId(SelectedItemViewModel selectedItemModel)
 {
     if (selectedItemModel == null)
     {
         return 0;
     }
     long id;
     long.TryParse(selectedItemModel.Id, out id);
     return id;
 }
 public SelectedItemViewModel GetTheme(string id)
 {
     long parseResult;
     if (long.TryParse(id, out parseResult))
     {
         return GetTheme(parseResult);
     }
     else if (!string.IsNullOrEmpty(id))
     {
         var theme = new SelectedItemViewModel()
         {
             Id = id,
             Text = SubjectIdPrefixHelper.Trim(id)
         };
         return theme;
     }
     return null;
 }
 private static long? GetSelectedId(SelectedItemViewModel viewModel)
 {
     long id;
     if (viewModel != null && long.TryParse(viewModel.Id, out id))
     {
         return id;
     }
     return null;
 }