WPF——TargetNullValue(如何在绑定空值显示默认字符)

说明：在数据绑定时，如果有些字段为空值，那么在数据绑定时可以用默认值来显示为空的字段。

 1  <Grid>
 2         <ListBox x:Name="lstPeople" Width="400">
 3             <ListBox.ItemTemplate>
 4                 <DataTemplate>
 5                     <StackPanel Orientation="Horizontal">
 6                         <TextBlock Text="{Binding Path=FirstName}" />
 7                         <TextBlock Text=" " />
 8                         <TextBlock Text="{Binding LastName}" />
 9                         <TextBlock Text=", " />
10                         <TextBlock Text="{Binding Age, TargetNullValue='Age Unknown'}" />
11                     </StackPanel>
12                 </DataTemplate>
13             </ListBox.ItemTemplate>
14         </ListBox>
15     </Grid>

 1  public partial class MainWindow : Window
 2     {
 3         List<Person> lst;
 4 
 5         public MainWindow()
 6         {
 7             InitializeComponent();
 8             lst = new List<Person>();
 9             lst.Add(new Person() {FirstName="John", LastName="Doe", Age=34});
10             lst.Add(new Person() { FirstName = "Jane", LastName = "Doe" });
11             lst.Add(new Person() { FirstName = "Jack", LastName = "Frost", Age = 300 });
12         }
13 
14         private void Window_Loaded(object sender, RoutedEventArgs e)
15         {
16             lstPeople.ItemsSource = lst;
17         }
18     }
19 
20     public class Person
21     {
22         public string FirstName { get; set; }
23         public string LastName { get; set; }
24         public int? Age { get; set; }
25     }