private bool CanSaveCommandExecute() { bool isCategoryNameUnique = true; if (categories.FirstOrDefault(a => a.CategoryName == CategoryName) != null && isAddition) { isCategoryNameUnique = false; } if (string.IsNullOrEmpty(CategoryName) || SelectedType == null || CategoryName.Any(a => char.IsDigit(a)) || !isCategoryNameUnique) { return(false); } else { return(true); } }