数据绑定在XAML的SelectedItem

Question

请看看这个：

<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}" 
      DataContext="{StaticResource vm}"> 
     <Grid.ColumnDefinitions> 
      <ColumnDefinition Width="194*"/> 
      <ColumnDefinition Width="489*"/> 
     </Grid.ColumnDefinitions> 
     <ListView HorizontalAlignment="Left" 
        ItemsSource="{Binding Path=Places}" 
        SelectedItem="{Binding Path=SelectedPlace, Mode=TwoWay}" Margin="0,96,0,0"> 
      <ListView.ItemTemplate> 
       <DataTemplate> 
        <StackPanel Orientation="Horizontal"> 
         <TextBlock Text="{Binding Path=Title}"/> 
        </StackPanel> 
       </DataTemplate> 
      </ListView.ItemTemplate> 
     </ListView> 

     <StackPanel Grid.Column="0" HorizontalAlignment="Left"> 

     <TextBlock 
     VerticalAlignment="Top" 
     Text="{Binding SelectedPlace.Title}" Margin="0,64,0,0"/> 
     </StackPanel> 


    </Grid> 

我在路过的地方名单，其做工精细和列表被显示在视图中。问题是selectedItem。智能感知在这里找到属性

Text="{Binding SelectedPlace.Title}" 

但它不显示在视图中。 当我把一个断点在我的视图模型，我可以看到，该值的变化：

public class MainViewModel : ViewModelBase 
    { 
     public ObservableCollection<Place> Places { get; set; } 

     public Place _selectedPlace { get; set; } 

     public Place SelectedPlace 
     { 
      get { return _selectedPlace; } 
      set { _selectedPlace = value; } 
     } 

     public MainViewModel() 
     { 
      Places = new ObservableCollection<Place>() 
      { 
       new Place() {Title = "London", Description = "London is a nice..."}, 
       new Place() {Title = "Dublin", Description = "Dublin is a ...."} 
      }; 
     } 
    } 

有谁知道我缺少什么？谢谢

Answer 1

您需要调用RaisePropertyChanged。

 public Place SelectedPlace 
     { 
      get { return _selectedPlace; } 
      set 
      { _selectedPlace = value; 
       RaisePropertyChanged("SelectedPlace")} 
      } 
     } 

而且你应该也可能初始化此属性：

public MainViewModel() 
    { 
     Places = new ObservableCollection<Place>() 
     { 
      new Place() {Title = "London", Description = "London is a nice..."}, 
      new Place() {Title = "Dublin", Description = "Dublin is a ...."} 
     }; 
     SelectedPlace = Places[0]; 
    } 

并且通过使SelectedPlace属性的支持字段私有字段请你帮个忙。你可能想改变它，因为这：

public Place _selectedPlace { get; set; } 

到

private Place _selectedPlace;