WPF TwoWay数据绑定限制

时间:2009-10-29 04:07:03

标签: c# wpf data-binding

假设WPF TwoWay数据绑定 Wont 对没有焦点的控件有效是否安全?

例如,在以下代码中。

 <Window.Resources>
        <XmlDataProvider x:Key="TestBind1" XPath="/BindTest1">
            <x:XData>
                <BindTest1 xmlns="">
                    <Value1>True</Value1>
                </BindTest1>
            </x:XData>
        </XmlDataProvider>
    </Window.Resources>
    <StackPanel>
        <GroupBox>
            <StackPanel>
                <RadioButton Content="Value1" IsChecked="{Binding Source={StaticResource TestBind1},Mode=TwoWay, XPath=Value1}"/>
                <RadioButton Content="Value2"/>
            </StackPanel>
         </GroupBox>
        <Button Content="Analyse" Click="OnAnalyseClicked"/>

    </StackPanel>

当我点击radiobutton Value2时,BindTest1 / Value1的值将保持 true ,因为radiobutton Value1在没有焦点的情况下改变了吗?

这是WPF的正常行为吗?我知道我可以通过使用各种技术来避免这种情况,但我想问这是否正常,或者我的Xaml缺少一些导致此问题的参数。

2 个答案:

答案 0 :(得分:1)

绑定更新,无论控件是否具有焦点。我的猜测是你的XAML还有其他错误。

答案 1 :(得分:1)

最后,我找到了答案。基本上,RadioButtons的绑定会中断,因为每次更改绑定时,radiobuttons都会更改组中其他按钮的选中状态

我找到了答案here,它专门用于RadioButton并防止绑定被更改。

我用来修复绑定的示例类。

 /// <summary>
    /// data bound radio button
    /// </summary>
    public class DataBoundRadioButton : RadioButton
    {
        /// <summary>
        /// Called when the <see cref="P:System.Windows.Controls.Primitives.ToggleButton.IsChecked"/> property becomes true.
        /// </summary>
        /// <param name="e">Provides data for <see cref="T:System.Windows.RoutedEventArgs"/>.</param>
        protected override void OnChecked(RoutedEventArgs e)
        {
            // Do nothing. This will prevent IsChecked from being manually set and overwriting the binding.
        }

        /// <summary>
        /// Called by the <see cref="M:System.Windows.Controls.Primitives.ToggleButton.OnClick"/> method to implement a <see cref="T:System.Windows.Controls.RadioButton"/> control's toggle behavior.
        /// </summary>
        protected override void OnToggle()
        {
            BindingExpression be = GetBindingExpression(RadioButton.IsCheckedProperty);
            Binding bind = be.ParentBinding;

            Debug.Assert(bind.ConverterParameter != null, "Please enter the desired tag as the ConvertParameter");

            XmlDataProvider prov = bind.Source as XmlDataProvider;
            XmlNode node = prov.Document.SelectSingleNode(bind.XPath);
            node.InnerText = bind.ConverterParameter.ToString();

        }
    }