UserControl属性绑定没有更新DataContext
本文关键字:更新 DataContext 属性 绑定 UserControl | 更新日期: 2023-09-27 17:50:44
我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,实现了OnPropertyChanged,并使用了MainWindow中的控件。
当我单击UserControl中的Browse按钮时,DependencyProperty"FilePath"被正确设置(并且文本框获得路径字符串),但模型似乎不起作用。
附加信息:如果我使用一个普通的文本框而不是UserControl,那么
<TextBox Text="{Binding InputFile}"/>
当我在框中输入一些东西时,模型被正确更新。如果我在UserControl中手动输入一些东西(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>
这是我使用INotifyPropertyChanged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MainWindow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)
}
}
这是我如何使用2个控件(2个例子,他们都没有工作):
<cust:FileBrowserTextBox Label="Input File" FilePath="{Binding InputFile}"/>
<cust:FileBrowserTextBox Label="Input File" FilePath="{Binding Path=InputFile, Mode=TwoWay,
RelativeSource={RelativeSource FindAncestor,
AncestorType=Window}}"/>
任何帮助都将非常感激。
更新和解决方案:
根据@AnatoliyNikolaev的建议(感谢他对UpdareSourceTrigger的解释)和@Karuppasamy在用户控制中可以这样做(使用UpdateSourceTrigger明确地,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可以像这样(注意BindsTwoWayByDefault):
public static readonly DependencyProperty FilePathProperty =
DependencyProperty.Register("FilePath", typeof(string), typeof(FileBrowserTextBox), new FrameworkPropertyMetadata(string.Empty, new PropertyChangedCallback(OnFilePathPropertyChanged)) { BindsTwoWayByDefault = true });
所以最后在主窗口中我可以简单地这样写:
<cust:FileBrowserTextBox FilePath="{Binding Path=InputFile}" />
尝试将您的依赖属性设置为UpdateSourceTrigger
到PropertyChanged
:
默认值是 default ,它返回目标依赖属性的默认UpdateSourceTrigger值。但是,大多数依赖属性的默认值是
PropertyChanged
,而Text属性的默认值是LostFocus
。
的例子:
<local:FileBrowserTextBox FilePath="{Binding Path=InputFile,
Mode=TwoWay,
UpdateSourceTrigger=PropertyChanged}" />
希望我理解你的问题,
我也尝试过,并将UpdateSourceTrigger设置为PropertyChanged,同时在UserControl的XAML代码中绑定TextBox。下面是我的代码
<TextBox Width="200" Name="txtFilepath" Text="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}}, Path=FilePath, UpdateSourceTrigger=PropertyChanged}"/>
<Button Width="40" Content=" ... " Click="BrowseButton_Click"/>
它正在工作。
谢谢