如何以編程方式綁定DataTemplate內的控件的（依賴項）屬性？

Question

TextBlock駐留在DataTemplate，因此我不能用它的名字來引用它。那麼如何以編程方式將其（例如）Text屬性綁定？

XAML：

<UserControl x:Class="MyNameSpace.MyCustomControl" ... > 
    ... 
    <ListBox ItemsSource="{Binding Path=ItemsSource}"> 
     <ListBox.ItemTemplate> 
      <DataTemplate> 
       <StackPanel Orientation="Horizontal"> 
        <TextBlock/> 
       </StackPanel> 
      </DataTemplate> 
     </ListBox.ItemTemplate> 
    </ListBox> 
    ... 
</UserControl> 

代碼：

public partial class MyCustomControl : UserControl { 
    ... 

    public static readonly DependencyProperty DataSourceProperty = 
     DependencyProperty.Register("DataSource", typeof (IEnumerable), 
            typeof (MyCustomControl), 
            new PropertyMetadata(default(IEnumerable))); 

    public IEnumerable DataSource { 
     get { return (IEnumerable) GetValue(DataSourceProperty); } 
     set { SetValue(DataSourceProperty, value); } 
    } 

    public static readonly DependencyProperty MemberPathProperty = 
     DependencyProperty.Register("MemberPath", typeof (string), 
            typeof (MyCustomControl), 
            new PropertyMetadata(default(string))); 

    public string MemberPath { 
     get { return (string) GetValue(MemberPathProperty); } 
     set { SetValue(MemberPathProperty, value); } 
    } 
    ... 
    public MyCustomControl() { 
     InitializeComponent(); 

     var binding = new Binding(MemberPath); 
     BindingOperations.SetBinding(/*how do I refer to the TextBlock here ???*/, 
            TextBox.TextProperty, binding); 
    } 
    ... 
} 

預期用法例如：

<my:MyCustomControl DataSource="{Binding Path=SomeModelCollection}" MemberPath="Name" 

哪裏SomeModelCollection就像ObservableCollection<SomeModel>一些數據模型屬性（SomeModel有一個名爲Name屬性）

Answer 1

您可以使用VisualTreeHelper獲取TextBlock。這種方法將讓你出現在一個ListBoxItem的視覺樹所有TextBlockes：

public IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj) 
      where T : DependencyObject 
{ 
    if(depObj != null) 
    { 
     for(int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++) 
     { 
      DependencyObject child = VisualTreeHelper.GetChild(depObj, i); 
      if(child != null && child is T) 
      { 
       yield return (T)child; 
      } 

      foreach(T childOfChild in FindVisualChildren<T>(child)) 
      { 
      yield return childOfChild; 
      } 
     } 
    } 
} 

用法：

TextBlock textBlock = FindVisualChildren<TextBlock>(listBoxItem) 
         .FirstOrDefault(); 

但我還是建議做在代碼中做背後的XAML綁定來代替。

如果ItemSource爲ObservableCollection<MyModel>和MyModel包含財產Name，它可以在XAML做過這樣的：

<DataTemplate> 
    <StackPanel Orientation="Horizontal"> 
     <TextBlock Text="{Binding Name}"/> 
    </StackPanel> 
</DataTemplate> 

由於ListBoxItemDataContext將MyModel，因此你可以直接像提到綁定到Name屬性以上。