为什么数据绑定不与工作的PropertyChanged？ [英] Why data binding is not working with PropertyChanged?

问题描述

我是新来的XAML和Windows 8手机的发展和学习有关数据绑定。 这里，有人建议我需要使用，

I am new to XAML and Windows 8 phone development and learning about data binding. Here, it is suggested that I need to use,

UpdateSourceTrigger=PropertyChanged

但是，当我尝试使用它在我的XAML中，它给错误为请求值的PropertyChanged找不到。相反，它与

But when I try to use it in my xaml, it is giving error as 'Requested value 'PropertyChanged' not found.' Instead it is working correctly with,

UpdateSourceTrigger=Default

我做错了什么，或者是在新版本中已过时。

I am doing something wrong, or it is deprecated in newer versions.

我的代码示例，

 <TextBox x:Name="txt1" Height="100" Width="100"></TextBox>

 <TextBlock Grid.Row="1" x:Name="txt2" Height="100" Width="100" 
    Text="{Binding Text,ElementName=txt1,
 UpdateSourceTrigger=PropertyChanged}"></TextBlock>

感谢。

Thanks.

推荐答案

UpdateSourceTrigger = PropertyChanged的未在Windows Phone的XAML支持。

UpdateSourceTrigger=PropertyChanged is not supported in Windows Phone XAML.

您可以使用 UpdateSourceTrigger =明确代替，
和处理后面的代码的源代码的更新：

You can use UpdateSourceTrigger=Explicit instead, and handle the source updating in the code behind:

private void OnTextBoxTextChanged( object sender, TextChangedEventArgs e )
{
  TextBox textBox = sender as TextBox;
  BindingExpression bindingExpr = textBox.GetBindingExpression( TextBox.TextProperty );
  bindingExpr.UpdateSource();
}

另一种方法是使用的 Coding4Fun图书馆 BindingHelper。在这种情况下，语法是：

Another alternative would be to use Coding4Fun's library BindingHelper. in that case, the syntax would be:

<TextBox   
  Text="{Binding FooBar, Mode=TwoWay}" 
  local:TextBinding.UpdateSourceOnChange="True" />

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