Trying to get a better understanding of SelectedValuePath and IsSynchronizedWithCurrentItem
- by rasx
The following XAML produces a run-time Binding error when I click on an item in the ListBox:
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:sys="clr-namespace:System;assembly=mscorlib"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Class="WpfApplication1.MainWindow"
x:Name="Window"
Title="MainWindow"
Width="640" Height="480">
<Window.Resources>
<x:Array x:Key="strings" Type="{x:Type sys:String}">
<sys:String>one</sys:String>
<sys:String>two</sys:String>
<sys:String>three</sys:String>
<sys:String>four</sys:String>
</x:Array>
</Window.Resources>
<Grid>
<ListBox
DataContext="{StaticResource strings}"
IsSynchronizedWithCurrentItem="True"
ItemsSource="{Binding}"
SelectedValuePath="{Binding /Length}">
<ListBox.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.Resources>
<Style TargetType="{x:Type Label}">
<Setter Property="Background" Value="Yellow"/>
<Setter Property="Margin" Value="0,0,4,0"/>
<Setter Property="Padding" Value="0"/>
</Style>
</Grid.Resources>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<!-- Row 0 -->
<Label Grid.Column="0" Grid.Row="0">String:</Label>
<TextBlock
Grid.Column="1"
Grid.Row="0"
Text="{Binding}"/>
<!-- Row 1 -->
<Label Grid.Column="0" Grid.Row="1">Length:</Label>
<TextBlock
Grid.Column="1"
Grid.Row="1"
Text="{Binding Length, Mode=Default}"/>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Window>
This is the run-time Binding error message:
System.Windows.Data Error: 39 : BindingExpression path error: '3' property not found on 'object' ''String' (HashCode=1191344027)'. BindingExpression:Path=3; DataItem='String' (HashCode=1191344027); target element is 'ListBox' (Name=''); target property is 'NoTarget' (type 'Object')
I would like the selected value of the ListBox to be the Length of the selected String object. What is wrong with my SelectedValuePath Binding syntax? Are there any related issues with IsSynchronizedWithCurrentItem?
