private void DeleteButtonOnToolBarItemClick(object sender, ItemClickEventArgs e) { if (CategoryTreeListControl.SelectedItem is Category category) { if (MessageBoxService.AskForDelete(category.Title) == true) { using (var dbContext = new FarnahadManufacturingDbContext()) { var categoryInDb = dbContext.Categories.First(item => item.Id == category.Id); if (dbContext.Categories.Any(item => item.ParentCategoryId == categoryInDb.Id)) { MessageBoxService.CannotDeleteParent(categoryInDb.Title); } else { dbContext.Categories.Remove(categoryInDb); dbContext.SaveChanges(); LoadCategories(); LoadCategoriesTreeList(); } } } } else { // No Valid Item Selected } }