使用 mode=twoway 进行数据绑定时出错
全部， 我在这里用头撞墙。我需要的很简单，而且我确信有一个简单的答案，但我似乎找不到它。 情况：我有一个 Silver light 4.0 应用程序，目前正在将字符串列表绑定到 Items 控件。在数据模板中，我有一个简单的文本框，我正在执行非常基本的绑定“{Binding}”。我需要将绑定更新为双向，以便编辑自动推回我的数据上下文。
这是更新绑定之前的项目控件：
<ItemsControl x:Name="spLiftHeader" ItemsSource="{Binding Path=WeekLabels}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel x:Name="spLiftHeader" Orientation="Horizontal" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
**<TextBox x:Name="txtWeekLbl" Text="{Binding}" Foreground="Black" Width="125" TextAlignment="Center"/>**
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
这是绑定更改之后的项目控件：
<ItemsControl x:Name="spLiftHeader" ItemsSource="{Binding Path=WeekLabels}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel x:Name="spLiftHeader" Orientation="Horizontal" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
**<TextBox x:Name="txtWeekLbl" Text="{Binding Mode=TwoWay}" Foreground="Black" Width="125" TextAlignment="Center"/>**
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
我只是简单地将“Mode=TwoWay”添加到绑定中。 更新后，我收到了令人惊讶的无用错误 4004 “System.Windows.Markup.XamlParseException：在“System.Windows.Data.Binding”上提供值引发异常”并且行/位置参考点正确执行我更新的绑定。 如何将双向模式添加到简单绑定中？ 提前致谢。 缺口
All,
I'm pounding my head against the wall here. What I need is simple, and I'm sure there is a simple answer, but I can't seem to find it.
Situation: I have a Silver light 4.0 app and I'm currently binding a list of strings to an Items control. In the data template for that I have a simple text box that I was doing very basic Binding "{Binding}". I need to update the binding to be twoway so the edits are automatically pushed back to my datacontext.
Here is the Items control before I update the binding:
<ItemsControl x:Name="spLiftHeader" ItemsSource="{Binding Path=WeekLabels}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel x:Name="spLiftHeader" Orientation="Horizontal" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
**<TextBox x:Name="txtWeekLbl" Text="{Binding}" Foreground="Black" Width="125" TextAlignment="Center"/>**
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
Here is the items control after the binding change:
<ItemsControl x:Name="spLiftHeader" ItemsSource="{Binding Path=WeekLabels}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel x:Name="spLiftHeader" Orientation="Horizontal" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
**<TextBox x:Name="txtWeekLbl" Text="{Binding Mode=TwoWay}" Foreground="Black" Width="125" TextAlignment="Center"/>**
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
I've just simply added the "Mode=TwoWay" to the binding.
After updating that, I get the amazingly useless error 4004
"System.Windows.Markup.XamlParseException: Provide value on 'System.Windows.Data.Binding' threw an exception" and the Line/Position reference points right do my updated Binding.
How does one add the Two Way mode to the simple binding?
Thanks in advance.
Nick
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到整个对象（在本例中为字符串）的双向绑定对于 Silverlight 来说没有任何意义，因此抛出异常是正确的。遗憾的是，这不是一个更有用的错误消息:)
当绑定中没有 Path 时，ItemsControl 可以使用 Object.ToString() 获取值，但它将把结果存储回哪里？它无法替换字符串，因为这需要将新的字符串对象放回集合中。双向绑定是通过针对对象属性的反射来完成的。
使用包含字符串属性并显式绑定到该属性的某些新对象的列表，而不是简单的字符串列表。这将使一切变得更加容易。 （确保您的新类和属性实现 INotifyPropertyChanged）。
Two-way binding to an entire object (a string in this case) makes no sense to Silverlight so it is correct to throw an exception. Shame it is not a more useful error message :)
When there is no Path in the binding the ItemsControl can fetch a value using Object.ToString(), but where will it store the result back? It can't replace the string as that would require placing a new string object back in the collection. Two-way binding is done via reflection against a property of an object.
Instead of a simple list of strings, use a list of some new object that contains a string property and explicitly bind to that property. It will make everything a lot easier. (Make sure your new class and property implement INotifyPropertyChanged).
我不是 100% 确定，但我不认为
Mode=TwoWay应该在 TextBox 本身中设置。如果这不起作用，请在两个上都尝试一下。但是，无论哪种情况，都不要使用
List作为该项目控件背后的数据源。当其中一项发生更改时，列表不会触发更改事件。使用ObservableCollection（来自System.Collections.ObjectModel命名空间）而不是ListI am not 100% sure, but I don't think the the
Mode=TwoWayshould be set in the TextBox itself.If that doesn't work, try it on both. However, in either case do not use
List<T>as a data source behind that items control. Lists do not fire changed event when one of its items has changed. UseObservableCollection<T>(from theSystem.Collections.ObjectModelnamespace) instead of theList<T>