更新DataTemplate中DataTemplate的綁定

Question

我有以下xaml;

<DataTemplate DataType="{x:Type NameSpace:Node}"> 
     <StackPanel Orientation="Horizontal"> 
      <TextBlock Text="{Binding Item.Value}"/> 
      <ContentControl Content="{Binding Item}"/> 
     </StackPanel> 
    </DataTemplate> 

    <DataTemplate DataType="{x:Type NameSpace:Item}"> 
     <TextBlock Text="{Binding Value}" /> 
    </DataTemplate> 

當我使用Node模板來顯示節點對象時，我得到兩個TextBlocks，它們都顯示相同的值。到現在爲止還挺好。項目更改時發生此問題。當Node類觸發INotifyPropertyChanged事件時，Node DataTemplate中的TextBlock會按預期更新，但Item DataTemplate中的TextBlock不會更新。

當Node類觸發IPropertyChanged事件時，如何獲取Item DataTemplate以更新其綁定？

更新 事實證明，上述工作適用於以下簡單場景;

的XAML

 <DataTemplate DataType="{x:Type DataTemplateExample:Node}"> 
      <StackPanel Orientation="Horizontal"> 
       <TextBlock Text="{Binding Item.Value}"/> 
       <ContentControl Content="{Binding Item}"/> 
      </StackPanel> 
     </DataTemplate> 

     <DataTemplate DataType="{x:Type DataTemplateExample:Item}"> 
      <TextBlock Text="{Binding Value}" /> 
     </DataTemplate> 
    </Window.Resources> 

    <Grid> 
     <StackPanel Orientation="Vertical"> 
      <ContentControl Content="{Binding MyNode}"/> 
      <Button Command="{Binding ChangeMyNodeItem}">Change Item</Button> 
     </StackPanel> 
    </Grid> 
</Window> 

C＃

public class MainViewModel 
{ 
    private readonly Node myNode; 
    private readonly DelegateCommand changeMyNodeItemCmd; 

    public MainViewModel() 
    { 
     myNode = new Node {Item = new Item("a")}; 
     changeMyNodeItemCmd = new DelegateCommand(()=> 
      myNode.Item = new Item("b")); 
    } 

    public Node MyNode { get { return myNode; } } 

    public ICommand ChangeMyNodeItem 
    { 
     get { return changeMyNodeItemCmd; } 
    } 
} 

public class Node : INotifyPropertyChanged 
{ 
    public event PropertyChangedEventHandler PropertyChanged; 

    private Item item; 
    public Item Item 
    { 
     set 
     { 
      item = value; 
      if (PropertyChanged != null) 
       PropertyChanged(this,new PropertyChangedEventArgs("Item")); 
     } 
     get { return item; } 
    } 
} 

public class Item 
{ 
    private readonly string value; 

    public Item(string value) 
    { 
     this.value = value; 
    } 

    public string Value 
    { 
     get { return value; } 
    } 
} 

在我真實的情景我使用代理服務器，我想這是什麼讓WPF困惑。項目實際上並沒有改變 - 它被重新映射。

最終我使用類似於ShadeOfGray提出的解決方案來解決問題。但我應該指出，除非您使用代理，否則這不是必需的。

Answer 1

從你發佈的內容我認爲你在錯誤的類中解僱NotifyPropertyChanged。類似的東西應該在你的場景中正常工作。

根據評論更新時間：

public class Node : INotifyPropertyChanged 
{ 
    private Item item; 

    public event PropertyChangedEventHandler PropertyChanged; 

    public Item Item 
    { 
     get 
     { 
      return item; 
     } 

     set 
     { 
      item = value; 

      this.NotifyPropertyChanged("Item"); 

      if (item != null) 
      { 
       item.ForcePropertyChanged("Value"); 
      } 
     } 
    } 

    protected void NotifyPropertyChanged(string propertyName) 
    { 
     if (PropertyChanged != null) 
     { 
      PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 
     } 
    } 
} 

public class Item : INotifyPropertyChanged 
{ 
    private string itemValue; 

    public Item() 
    { 
     this.Value = string.Empty; 
    } 

    public event PropertyChangedEventHandler PropertyChanged; 

    public string Value 
    { 
     get 
     { 
      return itemValue; 
     } 

     set 
     { 
      itemValue = value; 

      NotifyPropertyChanged("Value"); 
     } 
    } 

    public void ForcePropertyChanged(string propertyName) 
    { 
     if (PropertyChanged != null) 
     { 
      PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 
     } 
    } 

    protected void NotifyPropertyChanged(string propertyName) 
    { 
     if (PropertyChanged != null) 
     { 
      PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 
     } 
    } 
}