Question

我有一个Silverlight 2应用程序，用于验证数据OnTabSelectionChanged。我立即开始希望UpdateSourceTrigger不仅允许LostFocus，因为如果单击选项卡而不选择控件，则在验证之前不会更新LINQ对象。

我通过将焦点设置为另一个控件然后返回OnTextChanged解决了TextBoxes的问题：

Private Sub OnTextChanged(ByVal sender As Object, ByVal e As TextChangedEventArgs)
    txtSetFocus.Focus()
    sender.Focus()
End Sub

现在我试图在DataGrid中完成同样的黑客攻击。我的DataGrid使用在运行时为CellTemplate和CellEditingTemplate生成的DataTemplates。我尝试将TextChanged =“OnTextChanged”写入DataTemplate中的TextBox，但不会触发它。

有人有什么想法吗？

Answer 1

You can do it with a behavior applied to the textbox too

// xmlns:int is System.Windows.Interactivity from System.Windows.Interactivity.DLL)
// xmlns:behavior is your namespace for the class below
<TextBox Text="{Binding Description,Mode=TwoWay,UpdateSourceTrigger=Explicit}">
    <int:Interaction.Behaviors>
       <behavior:TextBoxUpdatesTextBindingOnPropertyChanged />
    </int:Interaction.Behaviors>
</TextBox>


public class TextBoxUpdatesTextBindingOnPropertyChanged : Behavior<TextBox>
{
    protected override void OnAttached()
    {
        base.OnAttached();

        AssociatedObject.TextChanged += new TextChangedEventHandler(TextBox_TextChanged);
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        AssociatedObject.TextChanged -= TextBox_TextChanged;
    }

    void TextBox_TextChanged(object sender, TextChangedEventArgs e)
    {
        var bindingExpression = AssociatedObject.GetBindingExpression(TextBox.TextProperty);
        bindingExpression.UpdateSource();
    }
}

Answer 2

此博客文章介绍了如何使用附加属性显式更新文本框的来源： http://www.thomasclaudiushuber.com/blog/2009/07/17/here-it-is-the-updatesourcetrigger-for-propertychanged-in-silverlight/

您可以轻松修改它以与其他控件一起使用...

Answer 3

我使用MVVM和Silverlight 4遇到了同样的问题。问题是绑定在文本框失去焦点之前不会更新源，但是将焦点设置在另一个控件上并不起作用。

我找到了一个使用两个不同博客文章组合的解决方案。我使用了Patrick Cauldwell的DefaultButtonHub概念代码，以及来自SmallWorkarounds.net的一个“SmallWorkaround”

http://www.cauldwell.net/patrick/blog/DefaultButtonSemanticsInSilverlightRevisited.aspx

www.smallworkarounds.net/2010/02/elementbindingbinding-modes.html

我的更改导致DefaultButtonHub类的以下代码：

public class DefaultButtonHub
{
    ButtonAutomationPeer peer = null;

    private void Attach(DependencyObject source)
    {
        if (source is Button)
        {
            peer = new ButtonAutomationPeer(source as Button);
        }
        else if (source is TextBox)
        {
            TextBox tb = source as TextBox;
            tb.KeyUp += OnKeyUp;
        }
        else if (source is PasswordBox)
        {
            PasswordBox pb = source as PasswordBox;
            pb.KeyUp += OnKeyUp;
        }
    }

    private void OnKeyUp(object sender, KeyEventArgs arg)
    {
        if (arg.Key == Key.Enter)
            if (peer != null)
            {
                if (sender is TextBox)
                {
                    TextBox t = (TextBox)sender;
                    BindingExpression expression = t.GetBindingExpression(TextBox.TextProperty);
                    expression.UpdateSource();
                }
                ((IInvokeProvider)peer).Invoke();
            }
    }

    public static DefaultButtonHub GetDefaultHub(DependencyObject obj)
    {
        return (DefaultButtonHub)obj.GetValue(DefaultHubProperty);
    }

    public static void SetDefaultHub(DependencyObject obj, DefaultButtonHub value)
    {
        obj.SetValue(DefaultHubProperty, value);
    }

    // Using a DependencyProperty as the backing store for DefaultHub.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty DefaultHubProperty =
        DependencyProperty.RegisterAttached("DefaultHub", typeof(DefaultButtonHub), typeof(DefaultButtonHub), new PropertyMetadata(OnHubAttach));

    private static void OnHubAttach(DependencyObject source, DependencyPropertyChangedEventArgs prop)
    {
        DefaultButtonHub hub = prop.NewValue as DefaultButtonHub;
        hub.Attach(source);
    }

}

这应包含在Silverlight的某些文档中：）

Answer 4

我知道这是个老消息......但我这样做是为了解决这个问题：

Text =“{Binding Path = newQuantity，UpdateSourceTrigger = PropertyChanged}”

Silverlight Datagrid上UpdateSourceTrigger LostFocus的解决方法？

4 个答案: