[英]UserControl Property Binding not Updating the DataContext
我創建了這個簡單的可重用控件來瀏覽文件。
然后我做了一個模型並實現了OnPropertyChanged並在MainWindow中使用了該控件。
當我單擊UserControl中的“瀏覽”按鈕時,DependencyProperty“FilePath”被正確設置(並且文本框獲取路徑字符串)但模型似乎不起作用。
附加信息:如果我使用普通文本框而不是UserControl廣告
<TextBox Text="{Binding InputFile}"/>
當我在框中輸入內容時,模型會正確更新。 如果我在UserControl中手動輸入內容(而不是通過“瀏覽”按鈕填充它,它無論如何都不起作用)
這是UserControl的代碼,該屬性在控件中正確設置:
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
}
}
}
這是XAML的摘錄:
<UserControl x:Class="DrumMapConverter.FileBrowserTextBox">
...
<Button Content=" ... " Click="BrowseButton_Click"/>
<TextBox Name="txtFilepath" Text="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}}, Path=FilePath}"/>
...
</UserControl>
這是我與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;
}
這是MainWindow類
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)
}
}
這是我如何使用2個控件(2個例子,它們都不起作用):
<cust:FileBrowserTextBox Label="Input File" FilePath="{Binding InputFile}"/>
<cust:FileBrowserTextBox Label="Input File" FilePath="{Binding Path=InputFile, Mode=TwoWay,
RelativeSource={RelativeSource FindAncestor,
AncestorType=Window}}"/>
任何幫助將非常感激。
更新和解決方案:
正如@AnatoliyNikolaev(感謝他對UpdareSourceTrigger的解釋)和用戶控件中的@Karuppasamy的建議,可以這樣做(明確使用UpdateSourceTrigger,因為它是一個文本框):
<TextBox Grid.Column="2" Name="txtFilepath" Text="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}}, Path=FilePath, UpdateSourceTrigger=PropertyChanged}"/>
然后DependencyProperty可以是這樣的(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我可以簡單地寫這個:
<cust:FileBrowserTextBox FilePath="{Binding Path=InputFile}" />
嘗試將依賴項屬性設置UpdateSourceTrigger
設置為PropertyChanged
:
默認值為Default ,它返回目標依賴項屬性的默認UpdateSourceTrigger值。 但是,大多數依賴項屬性的默認值是
PropertyChanged
,而Text屬性的默認值是LostFocus
。
例:
<local:FileBrowserTextBox FilePath="{Binding Path=InputFile,
Mode=TwoWay,
UpdateSourceTrigger=PropertyChanged}" />
希望我理解你的問題,
我嘗試過相同的操作,並在將UserControl的XAML代碼中的TextBox綁定時將UpdateSourceTrigger設置為PropertyChanged。 以下是我的代碼,
<TextBox Width="200" Name="txtFilepath" Text="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}}, Path=FilePath, UpdateSourceTrigger=PropertyChanged}"/>
<Button Width="40" Content=" ... " Click="BrowseButton_Click"/>
它正在發揮作用。
謝謝
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