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Apress pro Silverlight 3 in C# phần 9

Phát hành Silverlight 1.1 lần đầu tiên có hỗ trợ .Net, gồm có các ngôn ngữ .Net cơ bản, C# và Visual Basic. Thêm vào đó theo Microsoft, Silverlight 1.1 sẽ có sự hỗ trợ .Net cho các ngôn ngữ động như Ruby, Python, dynamic Visual Basic và Jscript đã có. Theo quan điểm của chúng tôi, các ngôn ngữ quan trọng để Silverlight hỗ trợ là C# và Visual Basic vì chúng cho phép các chuyên gia phát triển .Net có thể tạo các ứng dụng Silverlight. . | CHAPTER 16 DATA BINDING while reader.Read Create a Product object that wraps the current record. Product product new Product string reader ModelNumber string reader ModelName Convert.ToDouble reader UnitCost string reader Description string reader CategoryName Add to collection products.Add product finally con.Close return products When the user clicks the Get Products button the event-handling code calls the GetProducts method asynchronously private void cmdGetProducts_Click object sender RoutedEventArgs e StoreDbClient client new StoreDbClient client.GetProductsCompleted client_GetProductsCompleted client.GetProductsAsync When the product list is received from the web service the code stores the collection as a member variable in the page class for easier access elsewhere in your code. The code then sets that collection as the ItemsSource for the list private ObservableCollection products private void client_GetProductsCompleted object sender GetProductsCompletedEventArgs e try products e.Result lstProducts.ItemsSource products catch Exception err lblError.Text Failed to contact service. 561 CHAPTER 16 DATA BINDING Note Keen eyes will notice one unusual detail in this example. Although the web service returned an array of Product objects the client applications receives them in a different sort of package the ObservableCollection. You ll learn why Silverlight performs this sleight of hand in the next section. This code successfully fills the list with Product objects. However the list doesn t know how to display a Product object so it calls the ToString method. Because this method hasn t been overridden in the Product class this has the unimpressive result of showing the fully qualified class name for every item see Figure 16-6 . Figure 16-6. An unhelpful bound list You have three options to solve this problem Set the list s DisplayMemberPath property. For example set it to ModelName to get the result shown in Figure 16-5. Override the Product.ToStringO method to