c# - UserControl 属性绑定(bind)不更新 DataContext

Question

我已经创建了这个简单的可重用控件来浏览文件。

然后我做了一个模型并实现了 OnPropertyChanged 并在 MainWindow 中使用了控件。

当我单击 UserControl 中的“浏览”按钮时，DependencyProperty“FilePath”已正确设置(并且文本框获取路径字符串)但模型似乎无法正常工作。

附加信息:如果我使用普通文本框而不是我使用的 UserControl 广告

<TextBox Text="{Binding InputFile}"/>

当我在框中输入内容时，模型会正确更新。如果我在 UserControl 中手动输入内容(而不是通过浏览按钮填充它，它无论如何都不起作用)

这是 UserControl 的代码，在控件中正确设置了属性:

public partial class FileBrowserTextBox : UserControl
{
    public FileBrowserTextBox()
    {
        InitializeComponent();
    }

    // FilePath
    public static readonly DependencyProperty FilePathProperty =
        DependencyProperty.Register("FilePath", typeof(string), typeof(FileBrowserTextBox), new FrameworkPropertyMetadata(string.Empty, new PropertyChangedCallback(OnFilePathPropertyChanged)));

    public string FilePath
    {
        get { return (string)GetValue(FilePathProperty); }
        set { SetValue(FilePathProperty, value); }
    }
    static void OnFilePathPropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
    {
        var obj = o as FileBrowserTextBox;
        if (obj == null)
            return;
    }
    private void BrowseButton_Click(object sender, RoutedEventArgs e)
    {
        // Create OpenFileDialog 
        Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();
        // Set filter for file extension and default file extension 
        dlg.DefaultExt = ".txt";
        dlg.Filter = "TXT Files (*.txt)|*.txt|All Files (*.*)|*.*";
        // Display OpenFileDialog by calling ShowDialog method 
        Nullable<bool> result = dlg.ShowDialog();
        // Get the selected file name and display in a TextBox 
        if (result == true)
        {
            // Open document 
            string filename = dlg.FileName;
            FilePath = filename; // this works and updates the textbox
        }
    }
}

这是 XAML 的摘录:

<UserControl x:Class="DrumMapConverter.FileBrowserTextBox">
        ...
        <Button Content=" ... " Click="BrowseButton_Click"/>
        <TextBox Name="txtFilepath" Text="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}}, Path=FilePath}"/>
        ...
</UserControl>

这是我与 INotifyPropertyChanged 一起使用的模型:

public class DrumMapConverterDataModel :INotifyPropertyChanged
{
    public string InputFile
    {
        get { return inputFile; }
        set
        {
            inputFile = value;
            OnPropertyChanged("InputFile");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    // Create the OnPropertyChanged method to raise the event 
    protected void OnPropertyChanged(string name)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(name));
        }
    }

    private string inputFile;
}

这是主窗口类

public partial class MainWindow : Window
{
    private DrumMapConverterDataModel model;
    public MainWindow()
    {
        InitializeComponent();
        model = new DrumMapConverterDataModel();
        DataContext = model;
    }

    private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        MessageBox.Show(model.InputFile); // if i break here the model has no data changed (InputFile is null)
    }
}

这就是我使用 2 个控件的方式(2 个示例都不起作用):

<cust:FileBrowserTextBox  Label="Input File" FilePath="{Binding InputFile}"/>
<cust:FileBrowserTextBox  Label="Input File" FilePath="{Binding Path=InputFile, Mode=TwoWay, 
                       RelativeSource={RelativeSource FindAncestor, 
                           AncestorType=Window}}"/>

非常感谢任何帮助。

更新和解决方案:

正如 @AnatoliyNikolaev(感谢他对 UpdareSourceTrigger 的解释)和用户控件中的@Karuppasamy 所建议的那样，可以这样做(明确使用 UpdateSourceTrigger，因为它是一个文本框):

<TextBox Grid.Column="2" Name="txtFilepath" Text="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}}, Path=FilePath, UpdateSourceTrigger=PropertyChanged}"/>

那么 DependencyProperty 可以是这样的(注意 BindsTwoWayByDefault):

public static readonly DependencyProperty FilePathProperty =
    DependencyProperty.Register("FilePath", typeof(string), typeof(FileBrowserTextBox), new FrameworkPropertyMetadata(string.Empty, new PropertyChangedCallback(OnFilePathPropertyChanged)) { BindsTwoWayByDefault = true });

所以最后在 MainWindow 中我可以简单地写这个:

<cust:FileBrowserTextBox  FilePath="{Binding Path=InputFile}" />

Answer 1

尝试为您的依赖属性集 UpdateSourceTrigger到 PropertyChanged:

The default is Default, which returns the default UpdateSourceTrigger value of the target dependency property. However, the default value for most dependency properties is PropertyChanged, while the Text property has a default value of LostFocus.

例子:

<local:FileBrowserTextBox FilePath="{Binding Path=InputFile, 
                                             Mode=TwoWay,
                                             UpdateSourceTrigger=PropertyChanged}" />