WPF强制重新绑定

Question

我有一个不能继承DependencyObject或使用NotifyPropertyChanged的对象，而且我已经将它绑定到了相当多的控件上，所以当属性发生变化时，我不想转到每个控件并更改它在代码上的值，所以我在想，一定有一种方法可以告诉XAML用一两行代码“重新绑定”它绑定到的所有内容，而不是：

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

等等，等等...

这是一个过于简单的示例：

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;
        }
    }
}

我找到了一种方法，但它一点也不优雅，不幸的是，我不能只是将DataContext设置为新的天气实例，它需要相同的引用(这就是为什么我将其设置为null，以便它发生变化)：

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;
}   

提前感谢！

Answer 1

如果您有权访问要更新绑定的元素，则可以显式更新绑定。您可以检索元素上的绑定表达式，然后使用UpdateTarget()刷新UI，或使用UpdateSource刷新支持属性(如果要绑定到可编辑的内容，如TextBox)。

这里有一个简单的例子来演示它：

<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();
    }
}

(如果可能的话，我会推荐使用INotifyPropertyChanged。这样您就可以从后面的代码中提取逻辑。)