C# 自定义UserControl的WPF数据绑定问题

我在UserControl的DependencyProperty和TextBlock的DependencyProperty上使用数据绑定。我将这些绑定到属性TestValue。 首先，我用TestValue=“TestValue set First time！”初始化TestValue有效同时更新用户控件和文本块。
然后，通过Dispatcher，我每秒向TestValue写入一个随机值，而这个不起作用。TextBlock会更新，但UserControl不会更新

以下是我的主窗口代码：

//MainWindow.cs
public partial class MainWindow : Window
{
    private MainWindowViewModel viewModel;

    public MainWindow()
    {
        InitializeComponent();

        this.DataContext = this.viewModel = new MainWindowViewModel()
        {
            TestValue = "TestValue set first time!",
        };
    }
}

//MainWindow.xaml
<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local ="clr-namespace:RhinoTouchUIwpf;assembly="
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" x:Class="RhinoTouchUIwpf.MainWindow"
    SizeToContent="WidthAndHeight">
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="auto"/>
        <RowDefinition Height="auto"/>
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="auto"/>
    </Grid.ColumnDefinitions>
    <local:UserControl1 OperationName="{Binding TestValue, Mode=OneWay}" Grid.Row="0"/>
    <TextBlock Text="{Binding TestValue, Mode=OneWay}" FontSize="15" Grid.Row="1" />
</Grid>

TextBlock的文本每秒都会更改，UserControl1的文本不会更改。

---

我做错了什么？

您遇到的问题是

属性ChangedCallback中的这行代码：

((UserControl1)sender).OperationName = (String)e.NewValue;

这里的问题是，事件处理程序将通知您对同一属性的新更改。当您输入此功能时，它来自：

set { this.SetValue(MyDependencyProperty, value); }

有效地进入无限循环（依赖属性系统检测并停止对该函数的进一步调用）。去掉那条线就能解决你的问题

另一方面，如果您在XAML中定义了
属性changedCallback
，则可以完全取消该属性：

// On your UserControl element, add a x:Name="uc"
<TextBlock x:Name="NumberLabel" FontSize="20"  
           Text="{Binding OperationName, ElementName=uc, FallbackValue=0}" 
           Grid.Column="0" Grid.Row="1" HorizontalAlignment="Center" 
           VerticalAlignment="Center"/>

//在UserControl元素上添加一个x:Name=“uc”

这是完整的UserControl1.xaml

<UserControl x:Class="WpfApplication1.UserControl1"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" x:Name="uc"
             d:DesignHeight="300" d:DesignWidth="300">
    <Border BorderThickness="1" BorderBrush="Blue" x:Name="ControlBorder">
        <Grid Background="AliceBlue">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>
            <TextBlock x:Name="NumberLabel" FontSize="20"  
                        Text="{Binding OperationName, ElementName=uc, FallbackValue=0}" 
                        Grid.Column="0" Grid.Row="1" HorizontalAlignment="Center" 
                        VerticalAlignment="Center"/>
        </Grid>
    </Border>
</UserControl>



// On your UserControl element, add a x:Name="uc"
<TextBlock x:Name="NumberLabel" FontSize="20"  
           Text="{Binding OperationName, ElementName=uc, FallbackValue=0}" 
           Grid.Column="0" Grid.Row="1" HorizontalAlignment="Center" 
           VerticalAlignment="Center"/>

<UserControl x:Class="WpfApplication1.UserControl1"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" x:Name="uc"
             d:DesignHeight="300" d:DesignWidth="300">
    <Border BorderThickness="1" BorderBrush="Blue" x:Name="ControlBorder">
        <Grid Background="AliceBlue">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>
            <TextBlock x:Name="NumberLabel" FontSize="20"  
                        Text="{Binding OperationName, ElementName=uc, FallbackValue=0}" 
                        Grid.Column="0" Grid.Row="1" HorizontalAlignment="Center" 
                        VerticalAlignment="Center"/>
        </Grid>
    </Border>
</UserControl>