WPF Force rebind

Question

我有一個對象不能繼承DependencyObject，或者使用NotifyPropertyChanged，我將它綁定到了很多控件上，所以當屬性發生變化時，我不想去每個控件並改變它是在代碼值，所以我想必須有一個方法來告訴XAML爲「重新綁定」所有，它的綁定到的代碼的一個或兩行，而不是去：那麼在

label1.Content = myObject.DontNotifyThis; 
label2.Content = myObject.DontNotifyThisEither; 
label3.Content = myObject.DontEvenThinkOfNotifyingThis; 
label4.Content = myObject.NotSoFastPal; 

，等等...

這是一個過於簡單的例子：

XAML：

<Window x:Class="StackOverflowTests.Window1" 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Title="Window1" x:Name="window1" Height="300" Width="300" Loaded="window1_Loaded"> 
    <Grid x:Name="gridMain"> 
     <Grid.RowDefinitions> 
      <RowDefinition Height="Auto" /> 
      <RowDefinition Height="Auto" /> 
      <RowDefinition Height="Auto" /> 
     </Grid.RowDefinitions> 
     <Label Grid.Row="0" Content="{Binding Status}" ContentStringFormat="Today's weather: {0}" /> 
     <Label Grid.Row="2" Content="{Binding Temperature}" ContentStringFormat="Today's temperature: {0}" /> 
     <Label Grid.Row="1" Content="{Binding Humidity}" ContentStringFormat="Today's humidity: {0}" /> 
    </Grid> 
</Window> 

C＃：

using System.Windows; 

namespace StackOverflowTests 
{ 
    /// <summary> 
    /// Interaction logic for Window1.xaml 
    /// </summary> 
    public partial class Window1 : Window 
    { 
     Weather weather = new Weather("Cloudy", "60F", "25%"); 

     public Window1() 
     { 
      InitializeComponent(); 
      this.DataContext = weather; 
     } 

     private void window1_Loaded(object sender, RoutedEventArgs e) 
     { 
      weather.Status = "Sunny"; 
      weather.Temperature = "80F"; 
      weather.Humidity = "3%"; 
     }  
    } 

    class Weather 
    { 
     public string Status { get; set; } 
     public string Temperature { get; set; } 
     public string Humidity { get; set; } 

     public Weather(string status, string temperature, string humidity) 
     { 
      this.Status = status; 
      this.Temperature = temperature; 
      this.Humidity = humidity; 
     } 
    } 
} 

我找到了一種方法來做到這一點，但它不是優雅可言的，可惜的是，我不能只是設置的DataContext天氣的一個新實例，它需要是相同的（這就是爲什麼我將它設置爲null，所以它的變化）：

private void window1_Loaded(object sender, RoutedEventArgs e) 
{ 
    weather.Status = "Sunny"; 
    weather.Temperature = "80F"; 
    weather.Humidity = "3%"; 

    // bad way to do it 
    Weather w = (Weather)this.DataContext; 
    this.DataContext = null; 
    this.DataContext = w; 
} 

提前感謝！

Answer 1

如果您有權訪問要更新綁定的元素，則可以顯式更新綁定。您可以檢索元素上的綁定表達式，然後使用UpdateTarget（）刷新UI，或使用UpdateSource刷新支持屬性（如果要綁定到像TextBox一樣可編輯的內容）。

這裏有一個簡單的例子，演示了：

<StackPanel> 
    <TextBlock x:Name="uiTextBlock" Text="{Binding MyString}" /> 
    <Button Click="Button_Click" 
      Content="Rebind" /> 
</StackPanel> 

public partial class Window1 : Window 
{ 
    public string MyString { get; set; } 

    public Window1() 
    { 
     MyString = "New Value"; 

     InitializeComponent(); 
     this.DataContext = this; 
    } 
    int count = 0; 
    private void Button_Click(object sender, RoutedEventArgs e) 
    { 
     MyString = "Rebound " + ++count + " times"; 

     var bindingExpression = uiTextBlock.GetBindingExpression(TextBlock.TextProperty); 
     bindingExpression.UpdateTarget(); 
    } 
} 

（。我會建議使用INotifyPropertyChanged的，雖然如果在所有可能的方式，你可以從代碼中提取背後的邏輯）